SYSTEMATICS OF THE CAMBRIAN TRILOBITE

FAMILY NEPEIDAE, WITH REVISION OF

AUSTRALIAN SPECIES

by JOHN R. PATERSONCentre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, North Ryde, NSW 2109, Australia;

e-mail: agnostid@hotmail.com

Typescript received 6 June 2003; accepted in revised form 16 January 2004

Abstract: Taxonomy of the Cambrian trilobite family

Nepeidae is revised. Morphometric analyses of the genera

Nepea and Penarosa demonstrate that use of proportions

of linear dimensions of the cranidium to differentiate

species is invalid, and that infrageneric variation is con-

tinuous. The taxonomy and biostratigraphy of all Austra-

lian species of Nepeidae is revised. Species considered valid

herein include: Nepea narinosa (type species), N. tonsillata,

N. nans, Penarosa retifera (type species), P. elaticeps,

P. rhinodelphis, P. netenta, Loxonepea loxophrys (type spe-

cies) and Ferenepea hispida (type species). Folliceps is con-

sidered to be a junior subjective synonym of Nepea,

Trinepea is regarded as a junior subjective synonym of

Penarosa, and Ascionepea is considered to be a junior sub-

jective synonym of Ferenepea.

Key words: Nepeidae, Australia, Cambrian, morphometrics,

biostratigraphy.

The Cambrian trilobite family Nepeidae Whitehouse,

1939 represents a distinct group within the Ptychopario-

idea. Once thought to be endemic to Australia (Opik

1963a), nepeids are now known also from Antarctica,

China, New Zealand and Kazakhstan (Jago in Brock et al.

2000). The family is well represented with seven genera

and 23 formally described species (excluding those left

under open nomenclature); however, the literature is lim-

ited to fewer than a dozen papers, including Whitehouse

(1939), Opik (1963a, 1967, 1970), Palmer and Gatehouse

(1972), Jell (1977), Jell and Robison (1978) and Xiang

and Zhang (1985). Whitehouse (1939) erected the family

Nepeidae and genus Nepea, with type species Nepea nari-

nosa. Opik (1967, 1970) named all but five of the known

species of Nepeidae. Initially, Opik (1963a) revised the

concept of the Nepeidae, in addition to the cephalic mor-

phology of N. narinosa. He later described two new gen-

era from the Mindyallan fauna of north-west Queensland

(Opik 1967), and subsequently published the most com-

prehensive study on the group (Opik 1970), a monograph

documenting four genera and 25 species (ten of which

are left under open nomenclature) from the Middle Cam-

brian of north-west Queensland and the Northern Terri-

tory. Palmer and Gatehouse (1972) described Trinepea, a

new genus from Antarctica, the first record of nepeids

outside Australia. Jell (1977) described a new species of

Penarosa from north-west Queensland, and placed Trine-

pea in synonymy with Penarosa. Jell and Robison (1978),

in re-documenting a previously known Whitehouse

(1936, 1939) locality near Thorntonia Station, north-west

Queensland, recorded Penarosa retifera from a Middle

Cambrian trilobite faunule of the Currant Bush Lime-

stone. Xiang and Zhang (1985) described two new species

and one unnamed species of Nepea from China. Fortey

and Owens (1997) and Fortey and Hughes (1998) have

discussed the functional morphology of the preglabellar

boss in nepeids, and Jago (in Brock et al. 2000) provided

a synthesis on the stratigraphical and geographical distri-

bution of the group.

This study represents a taxonomic revision of the Aus-

tralian Nepeidae, with a re-examination of material col-

lected and described by F. W. Whitehouse, A. A. Opik

and P. A. Jell, in addition to new material I have collected

from the Middle Cambrian Gowers Formation, Georgina

Basin, north-west Queensland. The study includes a

morphometric analysis of the entire suite of specimens

(including new collections) upon which Whitehouse

(1939), Opik (1970) and Jell (1977) based their species

designations. Morphometric analysis was conducted in an

attempt to resolve fully the taxonomic status of all Aus-

tralian species of Nepea and Penarosa. The biostratigraphy

and geographical distribution of the group is also revised.

[Palaeontology, Vol. 48, Part 3, 2005, pp. 479–517]

ª The Palaeontological Association 479

BIOSTRATIGRAPHY

Australian occurrences

The nepeid trilobites documented in this paper are all

from Middle–Upper Cambrian strata exposed in the

north-west Queensland and eastern Northern Territory

regions of the Georgina Basin, and one occurrence in the

eastern Amadeus Basin in the Northern Territory. The

stratigraphy and correlation of these regions is illustrated

in Text-figure 1. The current Middle–Upper Cambrian

(Floran–Mindyallan) biostratigraphic scheme is largely

that developed by Opik (1961, 1963b, 1967, 1979) from

sampling of surface outcrop mostly from the Queensland

portion of the Georgina Basin. As outcrop in this basin is

generally poor and because measurable sections are lack-

ing, most of the information comes from spot localities

(J. Laurie, pers. comm. 2003). Because many of the

nepeid species erected by Opik (1967, 1970) are synony-

mized herein (see ‘Systematic palaeontology’), the bio-

stratigraphical ranges for some valid species have been

extended as a result. The ranges of all Australian species

considered valid herein are illustrated in Text-figure 2,

plotted against the northern Australian Cambrian bio-

stratigraphic scheme (sensu Geyer and Shergold 2000).

Locality and associated age information is presented in

the Appendix (section 1). Nepeids have also been repor-

ted from Cambrian successions in New South Wales

(Opik 1970), Victoria (Thomas and Singleton 1956;

Edwards et al. 1998), South Australia (Jago et al. 2002)

and Tasmania (Laurie et al. 1995), but none of the mater-

ial has been illustrated or discussed in detail, and apart

from Tasmanian, South Australian and Victorian occur-

rences (see Laurie et al. 1995, Jago et al. 2002 and

Edwards et al. 1998, respectively), field locality data are

insufficient for re-collection and the whereabouts of col-

lected specimens is unknown.

The oldest nepeid occurrence in Australia is represen-

ted by Nepea? sp. nov. NC, described by Opik (1970).

Locality information for this species is limited, with Opik

(1970) only recording that specimens came from a black

limestone bed in the Ross River Gorge, east of Alice

Springs, Northern Territory. This black limestone bed

represents part of the Giles Creek Dolomite (J. Laurie,

TEXT -F IG . 1 . Correlation of Cambrian successions in the north-west Queensland and eastern Northern Territory regions of the

Georgina Basin and eastern Amadeus Basin.

480 P A L A E O N T O L O G Y , V O L U M E 4 8

pers. comm. 2003). The co-occurrence of Xystridura indi-

cates an early Middle Cambrian (Ordian ⁄Early Templeto-

nian) age. It is doubtful that this species belongs to

Nepea. The apparent clavate shape of the preglabellar boss

and strongly tapered glabella (Opik 1970, pl. 7, fig. 4) is

characteristic of Loxonepea, but the fragmentary nature of

the specimens makes precise taxonomic assessment diffi-

cult.

Penarosa ranges from the Late Templetonian ⁄Floran

(Acidusus atavus Zone) to the early Undillan (Ptychagnos-

tus punctuosus Zone). Penarosa elaticeps and P. rhinodel-

phis occur with agnostoids typical of the Acidusus atavus

Zone (Opik 1979) from a single locality (M179) in the

lower part of the Currant Bush Limestone on Lancewood

Creek, Mount Drummond area, Northern Territory.

The type species of Penarosa, P. retifera, is widespread

and ranges from the Acidusus atavus Zone to the Ptychag-

nostus punctuosus Zone. The lowest stratigraphical occur-

rence of P. retifera is from the Arthur Creek Formation

(locality H4), near Huckitta Station, close to the Arthur

River, Northern Territory. Opik (1970) regarded speci-

mens from this locality as belonging to the Acidusus ata-

vus Zone. Specimens of P. retifera commonly occur in the

upper parts of the Currant Bush Limestone that crops

out in the Mount Drummond area of the Northern Terri-

tory (localities M180 and M186), and the Camooweal and

Lawn Hill areas of north-west Queensland (localities

M28, M123, M124, M130, M393, UQL256, UQL463).

Associated agnostoids from these localities indicate an age

spanning the Euagnostus opimus and Ptychagnostus punc-

tuosus zones (Jell and Robison 1978; Opik 1979; Laurie

1988). Specimens of P. retifera also occur in the coeval

and laterally interfingering Age Creek Formation in the

Morstone–Thorntonia area of north-west Queensland

(localities M157 and M160), and are abundant in the

Gowers Formation at Thorntonia Station (locality GF1),

which underlies the Currant Bush Limestone (Southgate

1986; Shergold and Southgate 1986). Agnostoids from the

Age Creek and Gowers formations are indicative of the

Euagnostus opimus Zone (Opik 1979).

Penarosa netenta is restricted to the Euagnostus opimus

Zone (Opik 1970, 1979; Jell 1977). This species occurs

only at Thorntonia Station, north-west Queensland, in

the vicinity of Chummy Bore (localities M412, QML136,

QML152). Opik (1970, 1979) regarded the shales, dolo-

mitic limestones and chert at Chummy Bore as represent-

ing the Inca Formation, while de Keyser and Cook (1972;

see also Jell 1977) coined the name Chummy Bore

TEXT -F IG . 2 . Biostratigraphic ranges of valid Australian species of Nepeidae plotted against Australian Cambrian stages and trilobite

biozones.

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 481

Formation for these rocks. Southgate (1986) conducted

detailed lithostratigraphic mapping and sedimentological

studies in this area and considered these rocks to repre-

sent part of the Gowers Formation, and regarded the

Chummy Bore Formation as being of doubtful utility.

Loxonepea loxophrys occurs in the Acidusus atavus Zone

portion of the Age Creek Formation (locality M122), and

in the Euagnostus opimus Zone portion of the Currant

Bush Limestone (locality M124), Camooweal area, north-

west Queensland (Opik 1970, 1979).

Nepea is a particularly long-ranging genus, spanning

the Late Templetonian ⁄Floran (Euagnostus opimus Zone)

to the Boomerangian (Lejopyge laevigata Zone). Nepea

nans (formerly Folliceps nans) represents the oldest spe-

cies, occurring in the Euagnostus opimus Zone (Opik

1979; Laurie 1988) of the Currant Bush Limestone in the

Camooweal area, north-west Queensland (localities M123,

M124).

Nepea tonsillata ranges within the Ptychagnostus punc-

tuosus and Goniagnostus nathorsti zones, and is known

only from a single locality (M54) in the V-Creek Lime-

stone, which crops out in Douglas Creek, south of Undil-

la homestead, north-west Queensland (Opik 1970). Opik

(1970, 1979) considered N. tonsillata and associated

agnostoids indicative of the Goniagnostus nathorsti Zone.

However, Opik (1979) listed only Doryagnostus magister

(¼ D. incertus) and Hypagnostus clipeus at locality M54.

D. incertus has an observed range from the punctuosus to

nathorsti zones in Gondwanan and Baltic regions (Wester-

gard 1946; Robison 1978; Peng and Robison 2000), and

thus N. tonsillata should be considered to range some-

where within these zones.

Nepea narinosa ranges from the Doryagnostus deltoides

Zone to the Lejopyge laevigata Zone. The lowest strati-

graphical occurrence of N. narinosa comes from the

V-Creek Limestone (locality M41) in the Camooweal

region of north-west Queensland, associated with agnos-

toids indicative of the Doryagnostus deltoides Zone

(Opik 1979; Laurie 1988). Specimens are rare in the

conformably overlying Mail Change Limestone. Speci-

mens of N. narinosa are abundant throughout the Split

Rock Sandstone, which has a diachronous contact

against both the Mail Change and the V-Creek lime-

stones in the Camooweal and Mount Isa regions of

north-west Queensland (localities M133, M141, M226,

M276, M344, M417, M421). Whitehouse (1939) origin-

ally described N. narinosa from the type locality of the

Split Rock Sandstone at Split Rock Waterhole on

Waroona Creek, north-west Queensland; this locality is

equivalent to Opik’s (1970) locality M417. Agnostoids

from the Split Rock Sandstone are indicative of the

Goniagnostus nathorsti Zone (Opik 1979). Specimens of

N. narinosa are also abundant in the Steamboat Sand-

stone (localities D54, D95, D108), which crops out in

the vicinity of Quita Creek in the Urandangi region of

north-west Queensland. Opik (1967, 1970, 1979) regar-

ded the agnostoids and polymerid trilobites from the

Steamboat Sandstone as belonging to the Lejopyge lae-

vigata Zone.

All Mindyallan species described by Opik (1967) are

herein considered to be synonymous, with Ferenepea

hispida representing the valid type species. For this rea-

son, the use of Ascionepea janitrix as a zonal taxon is

disregarded. Opik (1967) established what he called the

‘Zone of Passage’ (or the ‘Damesella torosa-Ascionepea

janitrix Zone’), which represented a transitional zone

from the Middle to Late Cambrian. Opik (1967, p. 8)

defined this zone as ‘a fauna [including A. janitrix] that

occurs in the span beginning with the last known Lejo-

pyge laevigata and ending with the first appearance of

Erediaspis eretes and its associates’. However, Daily and

Jago (1975) demonstrated that Lejopyge cos, which Opik

(1967) had recorded from this zone, is a synonym of

Lejopyge laevigata, and thus extended the range of that

species in Australia to the Acmarhachis quasivespa Zone,

therefore placing the Middle ⁄Late Cambrian boundary

within the latter zone. Furthermore, Daily and Jago

(1975) noted that Damesella torosa, which according to

Opik (1967) was confined to the ‘Zone of Passage’,

extended into the Erediaspis eretes Zone. As all Mindy-

allan nepeid species are synonymous with Ferenepea his-

pida, this species ranges from the Lejopyge laevigata

Zone to the Glyptagnostus stolidotus Zone (Opik 1967).

Therefore, F. hispida first appears at the top of the

Steamboat Sandstone (locality G103), in the Mungere-

bar–Mindyalla area of north-west Queensland. As noted

previously, the agnostoids from the Steamboat Sand-

stone are indicative of the Lejopyge laevigata Zone

(Opik 1967). Specimens of F. hispida occur throughout

the overlying Mungerebar Limestone, which crops out

at numerous localities (G8–10, G114, G119, G127,

G150, G417, G429) in the Mungerebar–Mindyalla

region of north-west Queensland. Agnostoids and poly-

merid trilobites suggest an early Mindyallan (Erediaspis

eretes Zone) age for the lower part of the Mungerebar

Limestone, extending into the Acmarhachis quasivespa

Zone in the upper part of the unit (Opik 1967).

Specimens of F. hispida are common in the light-

coloured shales of the O’Hara Shale in the Selwyn

Range, Duchess area, north-west Queensland (localities

D6, D28–29). The very diverse agnostoid and

polymerid faunas at locality D29 are indicative of the

Glyptagnostus stolidotus Zone (Opik 1967). Opik (1967)

also recorded F. hispida from the Georgina

Limestone (locality W1) in the Glenorminston–Sylvester

Creek area, north-west Queensland, associated

with a fauna indicative of the Glyptagnostus stolidotus

Zone.

482 P A L A E O N T O L O G Y , V O L U M E 4 8

Other Gondwanan occurrences

The oldest known occurrence of the Nepeidae outside

Australia is that of Trinepea (¼ Penarosa) trinodus from

the lower part of the Nelson Limestone in the Neptune

Range, Transantarctic Mountains, Antarctica (Palmer and

Gatehouse 1972). This species is a constituent of the

Amphoton oatesi faunule, which Cooper and Shergold

(1991) considered to be Floran–Undillan in age.

Nepea brevica and N. xinjiangensis have been described

from the Kensay Formation, northern Tianshan, Xinjiang,

North China (Xiang and Zhang 1985). These species

occur in the ‘upper trilobite assemblage’ within the unit

and are considered to be Undillan in age, spanning the

Ptychagnostus punctuosus–Goniagnostus nathorsti zones.

Undescribed nepeids have also been reported to occur

in limestone lenses within the Tasman Formation, north-

west Nelson, New Zealand, and are associated with coryn-

exochids, dolichometopids, solenopleurids, kopturids and

Pianaspis, which suggest a late Undillan age (Cooper in

Cooper and Bradshaw 1985; Shergold et al. 1985).

MORPHOMETRIC ANALYSIS

The great pioneering works of Opik (1963a, 1967, 1970)

were pivotal to our knowledge of the Nepeidae; however,

he erected an unusually large number of species, in par-

ticular of Nepea and Penarosa (Opik 1970). Fortey and

Hughes (1998, p. 647) have commented that ‘many of the

species erected by Opik are known from small numbers

of specimens, and some from unique ones’. Hughes and

Labandeira (1995) stated that insufficient sampling may

give rise to the appearance of discrete morphological

character states, which can be misinterpreted to have

taxonomic significance. Some of Opik’s (1970) localities

show the co-occurrence of several species of one genus at

a single locality, for example the type locality (M179) for

Penarosa elaticeps, P. meniscops, P. rhinodelphis and

P. zeabunda. In addition, species from M179 are based on

no more than five specimens. Labandeira and Hughes

(1994) noted that taxonomic errors result when intraspe-

cific variations are mistaken for interspecific differences,

leading to oversplit taxa containing species based on

minor and ⁄or inconsistent differences. In an attempt to

resolve fully the taxonomic status of all Australian species

of Nepea and Penarosa a detailed morphometric analysis

was conducted.

Bivariate and multivariate analyses were undertaken to

determine the validity of using linear characters to differ-

entiate species of Nepeidae. Methods used in this analysis

are similar to those presented by Hughes and Jell (1992)

and Hughes (1994). Material analysed includes all speci-

mens documented by Whitehouse (1939), Opik (1970)

and Jell (1977), plus additional material collected but not

documented or figured by Opik, and new collections of

mine (Appendix, section 2). Analysis of this pooled sam-

ple is designed to reveal both inter- and intraspecific vari-

ation and locality-related variation. A total of 117

cranidia were assessed based on nine linear measurements

(see Text-fig. 3). Symbols and terminology for sclerite

dimensions follow Shaw (1957); however, J2 here repre-

sents the maximum cranidial border width (tr.). The pre-

glabellar boss length and width (PBL and PBW,

respectively) have only been analysed bivariately for

Nepea. These nine linear measurements were selected

because they represent the morphological characters that

Opik (1970) considered to be taxonomically significant in

TEXT -F IG . 3 . Linear dimensions measured on cranidia of Penarosa and Nepea. Abbreviations follow Shaw (1957): B1, occipital–

glabellar length (sag.); F1, frontal area length (sag.); G1, cranidial border length (sag.); J2, maximum cranidial border width (tr.); J5,

post-palpebral cranidial width (tr.); K, occipital lobe width (tr.); K5, anterior glabellar width (tr.); PBL, maximum length of

preglabellar boss (sag.); PBW, maximum width of preglabellar boss (tr.).

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 483

determining different species. Linear distances were meas-

ured to the nearest tenth of a millimetre using Vernier

calipers. In cases where measurements were taken from

incomplete specimens with one side of an axially symmet-

rical structure missing, measurements obtained from the

complete half were doubled following the methods of

Labandeira and Hughes (1994. p. 493).

Bivariate analysis

A set of bivariate scatter plots have been established for

Penarosa and Nepea (see Text-figs 4–6); Folliceps is inclu-

ded with Nepea due to suspected synonymy. The mor-

phological variation in each of the nine linear characters

is assessed with reference to a standard measure for size,

in this case the occipital-glabellar length (B1) following

the methods of Hughes (1994, pp. 23–24). Data from lin-

ear characters were analysed using the Pearson product-

moment correlation coefficient (r) to determine the

extent to which two variables covary during growth. The

coefficient varies between zero and one, with zero indica-

ting no correlation and one indicating perfect linear cor-

relation. A more detailed definition and explanation of

this coefficient is provided by Imbrie (1956, p. 233) and

Shaw (1956, p. 1215). The reduced major axis (RMA)

was also calculated to determine growth relationships of a

pair of variables; both axes on the bivariate plots have

been log-transformed to determine RMA values. RMA

values indicate whether linear characters display allomet-

ric or isometric growth. Values significantly different

from 1Æ0 (at 95% confidence levels) indicate allometry,

and values equal to or not significantly different from 1Æ0indicate isometry. For further details of RMA, see Imbrie

(1956), Hayami and Matsukuma (1970) and Hughes

(1994). The Pearson product-moment correlation coeffi-

cient and RMA were calculated using PAST, version 1Æ01,

by Øyvind Hammer and David Harper (for details see

Hammer et al. 2001); r and RMA values for Penarosa and

Nepea are presented in Tables 1 and 2, respectively.

Results of bivariate analysis

The bivariate relationships of Penarosa and Nepea illus-

trate that the majority of the linear characters assessed,

with the exception of the cranidial border length (G1), do

not allow differentiation of more than one species for

each genus. The main reasons for this are: (1) all speci-

mens fall within a single trendline; (2) specimens of each

species in the pooled type-suite show some variation and

lie within the range of variation of other species; and (3)

the majority of type-suite specimens lie within the range

of variation shown by the locality-based collections. This

interpretation is further supported by the consistently

high correlation coefficient values for each character (i.e.

r > 0Æ85). This analysis demonstrates that these variations

are not species specific and in most cases represent allo-

metric growth patterns in these characters.

Penarosa. Opik (1970) was consistent in using linear

dimensions of the cranidium to differentiate between spe-

cies of Penarosa. In particular, he emphasized the relative

width of the interocular cheeks, length and width of the

frontal area, and shape of the glabella (i.e. anterior and

posterior width) to differentiate species. However, as seen

in Text-figure 4, all specimens from Opik’s (1970) type-

suite, specimens of P. netenta and those from new collec-

tions show tight clustering about a single trendline and

display continuous and gradational variation throughout

the sample, suggesting there is no justification for the

recognition of more than one morphotype. The relatively

low amount of variance within frontal area length (F1),

cranidial border width (J2), post-palpebral cranidial width

(J5), anterior glabellar width (K5), and occipital lobe

width (K) is also supported by the very high correlation

coefficients (r > 0Æ95) of each character (Table 1). The

RMA values indicate allometric growth in all characters

(Table 1).

The bivariate relationship between cranidial border

length (G1) and occipital-glabellar length (B1) shows that

there is a significant amount of scatter between these vari-

ables, suggesting marked size-independent variation (i.e.

variation is continuous throughout the sample and is not

correlated with overall size). The relatively low correlation

coefficient for the total sample reflects the high degree of

variability in the cranidial border length (r ¼ 0Æ888).

Growth of the cranidial border length is strongly posi-

tively allometric, indicating the relative size of the crani-

dial border length drastically increases throughout

holaspid ontogeny. The variation in cranidial border

length within and between species and locality-based col-

lections would suggest that growth was somewhat more

flexible than in other linear characters. However, speci-

mens of P. rhinodelphis appear to plot along the top of

the trendline (Text-fig. 4B). In plotting the ratio of crani-

dial border length ⁄ cranidial border width (G1 ⁄ J2) against

occipital-glabellar length (B1), type specimens of P. rhino-

delphis and three other specimens from locality M179

(the type locality of P. rhinodelphis) become isolated from

the major trendline, thus suggesting a separate species

(Text-fig. 4G). In pooling specimens of Opik’s (1970)

type-suite of species from M179 and new material from

this locality, plotting the ratio of G1 ⁄ J2 against B1 (Text-

fig. 5) yielded similar results to that of the total sample

(Text-fig. 4G). This relationship illustrates the discrimin-

ation of two distinct species consisting of P. zeabunda-

elaticeps and P. rhinodelphis at locality M179; P. meniscops

484 P A L A E O N T O L O G Y , V O L U M E 4 8

A B

C

E F

G

D

TEXT -F IG . 4 . Bivariate relationships of a pooled sample of Penarosa cranidia from type-suite and locality-based collections. Each

linear character is plotted against the standard measure for size, the occipital-glabellar length (B1). A, frontal area length (F1) versus

B1. B, cranidial border length (G1) versus B1. C, maximum cranidial border width (J2) versus B1. D, post-palpebral cranidial width (J5)

versus B1. E, occipital lobe width (K) versus B1. F, anterior glabellar width (K5) versus B1. G, ratio of cranidial border length and

width (G1 ⁄ J2) versus B1.

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 485

could be included in either group. However, trendlines in

Text-figures 4G and 5 suggest that in specimens of P. rhi-

nodelphis with an occipital-glabellar length longer than

about 3Æ5 mm, the ratio would stabilize with other species

of Penarosa and remain constant thereafter. One possible

explanation is that the trends in the two morphs from

M179 represent intraspecific heterochrony. Hughes (1994)

observed intraspecific heterochrony in Dikelocephalus,

where one particular population (‘Arcadia’) possessed

extraordinarily large eyes and long pygidial spines in

young holaspides, suggesting retention of juvenile features

in adulthood. However, by the late holaspid stage, Arca-

dia specimens are indistinguishable from specimens from

other populations, and hence this developmental differ-

ence only occurs in younger individuals. Hughes (1994)

could not explain this developmental shift in Dikelocepha-

lus because its preholaspid ontogeny is unknown. How-

ever, with regards to Penarosa, of the few meraspid

specimens from M179 illustrated by Opik (1970, pl. 17,

figs 5–6), the cranidial border does not display the same

ratio of length to width as in younger holaspides of P. rhi-

nodelphis, suggesting that the P. rhinodelphis morphotype

does not represent the prolonged expression of juvenile

features (i.e. an intraspecific heterochronic shift), and

thus exemplifies a distinct species.

Nepea. Opik (1970) used the same linear characters to

differentiate species in Nepea as in Penarosa; however, he

also emphasized that the relative length and width of the

preglabellar boss was species specific. Shape outline of the

preglabellar boss (i.e. circular or trapezoidal) was also a

governing factor in Opik’s species diagnoses; this is

reviewed in the discussion of Nepea narinosa (see ‘Sys-

tematic palaeontology’). Results of the bivariate plots for

Nepea (Text-fig. 6) demonstrate that specimens of the

type-suite and locality-based collections define a single

rectilinear trendline for the frontal area length (F1), crani-

dial border width (J2), post-palpebral cranidial width (J5),

anterior glabellar width (K5), occipital lobe width (K) and

the length and width of the preglabellar boss (PBL and

PBW, respectively). The relatively lower correlation coeffi-

cients for Nepea (r > 0Æ85) (Table 2), in comparison with

those for Penarosa, suggests remarkable plasticity of

these characters within the sample. Furthermore, many

specimens within the type-suite, for example those of

N. anoxys, N. avara, N. exserta and N. narinosa, are also

representatives of the locality-based collections (see

Appendix, section 2), supporting the contention that the

majority of type-suite specimens lie within the range of

variation shown by the locality-based collections. The

above evidence infers that there is only a single species

(based on these linear characters alone). The RMA values

indicate allometric growth in all characters (Table 2), thus

demonstrating similar growth patterns as those observed

in Penarosa.

Much of the morphological variability in Nepea is per-

haps related to non-biological factors such as compaction.

Although the specimens of Nepea analysed in this study

have not been tectonically distorted, some specimens pre-

TEXT -F IG . 5 . Bivariate relationship showing the ratio of cranidial border length and width (G1 ⁄ J2) versus occipital-glabellar length

(B1) of a sample of 17 cranidia of Penarosa from locality M179.

TABLE 1 . Reduced major axis (RMA) and Pearson product-

moment correlation coefficient (r) values relative to the occip-

ital-glabellar length (B1) in a pooled sample of Penarosa cranidia

from type-suite and locality-based collections.

Morphology RMA r

F1 1Æ679 0Æ969

G1 1Æ627 0Æ888

J2 1Æ508 0Æ957

J5 1Æ236 0Æ981

K 1Æ227 0Æ979

K5 1Æ288 0Æ979

486 P A L A E O N T O L O G Y , V O L U M E 4 8

served as internal moulds in porous sandstones appear to

have been modified by diagenetic compaction. Evidence

for this can be seen in the slight asymmetrical orientation

of the preglabellar boss (Pl. 1, fig. 11) and in the

deformed nature of the palpebral lobes (Pl. 1, figs 8, 11).

Morphometric studies of Dikelocephalus (Hughes 1994;

A B

DC

E F

HG

TEXT -F IG . 6 . Bivariate relationships of a pooled sample of Nepea cranidia from type-suite and locality-based collections. Each linear

character is plotted against the standard measure for size, the occipital-glabellar length (B1). A, frontal area length (F1) versus B1. B,

cranidial border length (G1) versus B1. C, maximum cranidial border width (J2) versus B1. D, post-palpebral cranidial width (J5)

versus B1. E, occipital lobe width (K) versus B1. F, anterior glabellar width (K5) versus B1. G, maximum length of preglabellar boss

(PBL) versus B1. H, maximum width of preglabellar boss (PBW) versus B1.

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 487

Labandeira and Hughes 1994) have demonstrated that

specimens from both sandstone and siltstone lithologies

that have undergone compaction do not exhibit any sig-

nificant separation in morphological trends. However, the

overall convexity of Dikelocephalus is considerably lower

than that found in Nepea, and it is to be expected that

compaction would have little effect on the measurements

of a trilobite with low convexity. Hughes (1994) noted

that orthogonal dimensions on arched (i.e. convex) surfa-

ces are most likely to be distorted by compression and

deformation. The best examples of such dimensions in

Nepea are the length and width of the strongly con-

vex preglabellar boss (PBL and PBW, respectively). The

correlation coefficients for PBL and PBW are the lowest

of all other pairwise correlation coefficients, with the

exception of the length and width of the cranidial border

(discussed below) (Table 2). This demonstrates that com-

paction probably accounts for at least some variation

within Nepea. The significant degree of variation in the

cranidial border length (G1) (Text-fig. 6B) is probably the

result of compaction of the preglabellar boss directly

influencing the relative length of the cranidial border. In

specimens of Nepea where compaction has resulted in the

anterior expansion of the preglabellar boss, the relative

length of the cranidial border will become shorter (sag.)

as the anterior margin of the boss encroaches onto the

border. This explains the significantly scattered distribu-

tion of specimens in the bivariate plot for the cranidial

border length (G1) and occipital-glabellar length (B1)

(Text-fig. 6B), and the extremely low correlation coeffi-

cient of G1 (r ¼ 0Æ464). Further evidence to support com-

pression in specimens of Nepea is discussed in the

revision of non-linear characters below.

Results of the bivariate analysis demonstrate that only

two species of Penarosa and one species of Nepea exist

when based solely on the linear characters assessed. They

also demonstrate how infrageneric and intraspecific vari-

ation and growth patterns in the linear dimensions of

holaspides (in addition to the effects of diagenetic proces-

ses such as compaction) was mistaken by Opik for inter-

specific differences when dealing with small sample sizes.

Multivariate analysis

Hughes (1994) noted that it is possible that subtle but

discrete patterns of covariance among sclerite dimensions,

which would reveal the presence of more than one spe-

cies, might not be detected by bivariate analysis. For this

reason, principal components analysis (PCA) was conduc-

ted for Penarosa and Nepea to determine possible further

morphological trends in the linear dimensions tested in

the bivariate analysis. These analyses only used specimens

that possess a complete data set, i.e. specimens from

which a measurement can be obtained for each character.

For a detailed summary of PCA, see Hughes (1994,

pp. 41–42).

Results of multivariate analysis

As noted by Hughes (1994), the overall importance of

each principal component (i.e. how much of the total

variation is accounted for by each principal component)

is represented by the eigen value. The contribution of

each input variable to each principal component is

referred to as the eigenweight (¼ eigenvector). The first

principal component (PC1) represents a discriminator of

size and accounts for the majority of variation when deal-

ing with the linear dimensions of a sample (Reyment

et al. 1984; Hughes 1994). Therefore it is important to

investigate subsequent principal components in an

attempt to detect the presence of discrete clusters that

may represent interspecific covariance within a sample.

Penarosa. The correlation matrix of the variables used for

the multivariate sample for Penarosa (Table 3) shows a

strong relationship between all pairs and a concordance

with the results of the bivariate analysis. The consistently

lower correlation values of the cranidial border length

(G1) with other variables reflect the growth patterns

observed in the bivariate analysis.

Results for Penarosa show that the first principal com-

ponent (PC1) accounts for 95Æ77 per cent of the total

variation in the sample (Table 4). The loadings of each

variate on PC1 are all positive and equal (Table 5), sug-

gesting that PC1 represents overall size. Therefore, as PC1

accounts for a considerable percentage of the total vari-

ation and largely reflects overall size, size differences

account for the majority of variation in the sample. This

can be attributed to the fact that the sample incorporates

a wide range of holaspid instars, as noted by Hughes and

Jell (1992) and Hughes (1994).

TABLE 2 . Reduced major axis (RMA) and Pearson product-

moment correlation coefficient (r) values relative to the occip-

ital-glabellar length (B1) in a pooled sample of Nepea cranidia

from type-suite and locality-based collections.

Morphology RMA r

F1 1Æ245 0Æ928

G1 1Æ981 0Æ464

J2 1Æ247 0Æ855

J5 1Æ235 0Æ904

K 1Æ293 0Æ964

K5 1Æ249 0Æ929

PBL 1Æ334 0Æ873

PBW 1Æ459 0Æ899

488 P A L A E O N T O L O G Y , V O L U M E 4 8

Principal component 2 (PC2) accounts for 2Æ14 per

cent of the total variance in the sample (Table 4). Princi-

pal components 3–7 account for only 2Æ09 per cent of the

total variance (Table 4), and as such limit the confidence

that can be placed in the results of these principal com-

ponents. These principal components reflect the influence

of one or more of the variables, but there is no consistent

pattern of covariance after PC1. The cranidial border

length (G1) has a strong negative loading on PC2, sug-

gesting that this principal component largely reflects vari-

ance in this character demonstrated in the bivariate

analysis. The cranidial border width (J2) shows a signifi-

cant positive loading on PC2, suggesting that specimens

show an inverse relationship between the length and

width of the cranidial border. Bivariate plots of the first

three principal components (Text-Fig. 7A–B) show that

there is a significant amount of overlap between speci-

mens of the type-suite and locality-based collections.

However, specimens of P. rhinodelphis and three smaller

specimens from locality M179 occupying an isolated

region of morphospace on principal components 1 and 2

(Text-fig. 7A) show low negative scores on PC2. The

inverse relationship of the cranidial border length and

width loadings on PC2 supports the differentiation of

these specimens as a distinct species, presumably P. rhino-

delphis. These results accord well with the bivariate rela-

tionship demonstrated by the ratio of cranidial border

length and width against occipital-glabellar length (Text-

fig. 4G).

Nepea. The correlation matrix of the variables included

for the analysis of Nepea (Table 6) can be closely correla-

ted with the bivariate analysis. The preglabellar boss

length and width were excluded from the PCA owing to

diagenetic factors influencing the sample (as discussed in

the bivariate analysis). Moreover, as the cranidial border

length (G1) is influenced by the dimensions of the pregla-

bellar boss, a separate analysis was conducted with the

exclusion of G1 for comparison. As expected, the lowest

correlation values are those of the cranidial border length

(G1) (Table 6), thus supporting the results of the bivariate

analysis.

Principal component 1 (PC1) accounts for 80Æ89 per

cent of the total variation in the sample (Table 7), with

loadings of each variable being positive and relatively

equal (Table 8), thus representing overall size. Principal

component 2 (PC2) accounts for 11Æ72 per cent of the

total variation; however, the most significant loading on

PC2 is the cranidial border length (G1), suggesting that

the variation in PC2 is the result of preservation. Princi-

pal component 3 (PC3) represents 3Æ72 per cent of the

total variation in the sample. The cranidial border width

(J2) shows a significant positive loading on PC3, reflecting

the positive allometric growth of this character noted in

the bivariate analysis. Principal component 4 (PC4)

accounts for 1Æ49 per cent of the total variation, with the

post-palpebral cranidial width (J5) having the greatest

influence, reflecting the strong allometry in this character.

Only 2Æ18 per cent of the total variation is divided among

the remaining three principal components (PC5–7) and,

hence, these are unlikely to represent any significant mor-

phological variation.

In order to assess the relationship of variables within

the sample that have not been significantly influenced by

compaction, a separate analysis was performed with the

exclusion of the cranidial border length (G1). As expected,

the principal components of this analysis subsequent to

PC1 were shown to be statistically similar to those in the

previous analysis subsequent to PC2, i.e. PC3 in the first

analysis is equivalent to PC2 in the second analysis, and

so on. Principal component 1 (PC1) accounts for 90Æ56

per cent of the total variation, demonstrating that overall

size accounts for an even more significant amount of the

TABLE 3 . Correlation matrix of cranidial characters of the

multivariate sample of Penarosa (n ¼ 48).

B1 F1 G1 J2 J5 K K5

B1 1

F1 0Æ971 1

G1 0Æ898 0Æ909 1

J2 0Æ962 0Æ97 0Æ875 1

J5 0Æ976 0Æ979 0Æ907 0Æ964 1

K 0Æ974 0Æ956 0Æ911 0Æ939 0Æ973 1

K5 0Æ98 0Æ972 0Æ916 0Æ973 0Æ976 0Æ975 1

TABLE 4 . Eigenvalues and percentage of variance accounted

for each principal component for Penarosa.

Principal

component 1 2 3 4 5 6 7

Eigenvalue 6Æ704 0Æ15 0Æ063 0Æ033 0Æ022 0Æ016 0Æ012

Percentage

variance

95Æ77 2Æ14 0Æ89 0Æ48 0Æ31 0Æ23 0Æ18

TABLE 5 . Eigenvectors for variables on principal components

in Penarosa.

Principal

component B1 F1 G1 J2 J5 K K5

1 0Æ381 0Æ381 0Æ361 0Æ377 0Æ382 0Æ379 0Æ383

2 0Æ178 0Æ118 )0Æ9 0Æ347 0Æ128 )0Æ001 0Æ086

3 0Æ261 )0Æ3 )0Æ196 )0Æ583 0Æ109 0Æ671 0Æ024

4 0Æ093 )0Æ596 0Æ058 0Æ372 )0Æ502 0Æ102 0Æ48

5 )0Æ823 )0Æ143 )0Æ044 0Æ21 0Æ335 0Æ368 0Æ097

6 0Æ238 )0Æ611 0Æ096 0Æ147 0Æ638 )0Æ306 )0Æ197

7 0Æ114 )0Æ041 0Æ081 0Æ439 )0Æ232 0Æ407 )0Æ752

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 489

total variation in the sample when diagenetically influ-

enced variables are removed. Principal component 2

(PC2) accounts for 4Æ38 per cent of the total variation.

Loadings of variables on PC2 are very similar to PC3 in

the first analysis, suggesting that the cranidial border

width (J2), occipital-glabellar length (B1) and occipital

lobe width (K) significantly influence this component.

Principal component 3 (PC3) accounts for 1Æ74 per cent

of the total variation, with loadings on variables that cor-

respond to those on PC4 in the first analysis, thus reflect-

ing influences by the post-palpebral cranidial width (J5),

occipital-glabellar length (B1), frontal area length (F1),

and, to a lesser extent, the occipital lobe width (K) and

anterior glabellar width (K5). Disregarding overall size

variation and diagenetic factors influencing principal

components, what seems to be driving the majority of

variation in other principal components are those varia-

bles that display strong allometric growth.

Bivariate plots of the first four principal components

from the first analysis (Text-fig. 8A–C) show a consider-

able amount of overlap among specimens. Unfortunately,

only 20 specimens from the type-suite and locality-based

collections were sufficiently well preserved to be included

in the analysis. Furthermore, over half of these specimens

represent N. narinosa or have come from associated local-

ities (e.g. M417 and M226; see Appendix, section 2). All

other species from the type-suite are represented by only

one or two specimens, therefore making it difficult to dif-

ferentiate discrete clusters that may represent distinct spe-

cies. Hence, there are insufficient grounds for recognizing

more than a single species of Nepea in the sample.

SYSTEMATIC PALAEONTOLOGY

Specimens used in this study come from the Commonwealth

Palaeontological Collection (prefix CPC) housed at Geoscience

Australia, Canberra, and the palaeontological collections of the

Queensland Museum, Brisbane (prefixes QMF and UQF). Mor-

phological terminology follows that of Whittington et al. (1997)

and Shaw (1957). Symbols in synonymy lists follow Matthews

A B

TEXT -F IG . 7 . Multivariate scatterplots for the first three principal components in a pooled sample of Penarosa cranidia from type-

suite and locality-based collections; n ¼ 48. A, principal component 1 (PC1) versus principal component 2 (PC2). B, principal

component 2 (PC2) versus principal component 3 (PC3).

TABLE 6 . Correlation matrix of cranidial characters of the

multivariate sample of Nepea (n ¼ 20).

B1 F1 G1 J2 J5 K K5

B1 1

F1 0Æ921 1

G1 0Æ314 0Æ493 1

J2 0Æ829 0Æ873 0Æ309 1

J5 0Æ883 0Æ912 0Æ43 0Æ886 1

K 0Æ936 0Æ896 0Æ446 0Æ763 0Æ894 1

K5 0Æ899 0Æ934 0Æ532 0Æ872 0Æ909 0Æ888 1

TABLE 7 . Eigenvalues and percentage of variance accounted

for each principal component for Nepea.

Principal

component 1 2 3 4 5 6 7

Eigenvalue 5Æ663 0Æ821 0Æ26 0Æ104 0Æ065 0Æ054 0Æ033

Percentage

variance

80Æ89 11Æ72 3Æ72 1Æ49 0Æ93 0Æ77 0Æ47

TABLE 8 . Eigenvectors for variables on principal components

in Nepea.

Principal

component B1 F1 G1 J2 J5 K K5

1 0Æ397 0Æ409 0Æ217 0Æ379 0Æ402 0Æ396 0Æ408

2 0Æ223 0Æ007 )0Æ944 0Æ221 0Æ082 0Æ04 )0Æ049

3 )0Æ376 0Æ021 0Æ058 0Æ706 0Æ128 )0Æ576 0Æ09

4 0Æ334 0Æ357 0Æ001 0Æ056 )0Æ778 )0Æ264 0Æ289

5 0Æ054 0Æ658 0Æ06 0Æ003 0Æ085 )0Æ098 )0Æ737

6 0Æ175 )0Æ395 0Æ175 0Æ549 )0Æ364 0Æ416 )0Æ421

7 )0Æ712 0Æ34 )0Æ158 0Æ069 )0Æ265 0Æ508 0Æ14

490 P A L A E O N T O L O G Y , V O L U M E 4 8

(1973). Photographed specimens have been coated with black,

water-based ink and then coated with ammonium chloride.

Stereo pairs were photographed using a specially constructed

platform, with a tilt of 4Æ5 degrees either side of the horizontal.

Class TRILOBITA Walch, 1771

Order PTYCHOPARIIDA Swinnerton, 1915

Suborder PTYCHOPARIINA Richter, 1932

Superfamily PTYCHOPARIOIDEA Matthew, 1887

Family NEPEIDAE Whitehouse, 1939

Revised diagnosis. Cranidium strongly vaulted, convex (sag.

and tr.); glabella gently to moderately tapered with two to

three pairs of deep, lateral glabellar furrows, glabellar length

(sag.) between 50 and 70 per cent cranidial length; medial

preglabellar boss occupying entire length (sag.) of preglabel-

lar field; wide fixigenae, post-palpebral cranidial width (tr.)

between 105 and 125 per cent cranidial length (sag.); eye rid-

ges well developed and bifurcate; posterolateral projections

of fixigenae well developed and strongly downsloping. Lib-

rigenae with long genal spines. Thorax with at least 20 seg-

ments; wide (tr.) pleurae. Pygidium small (micropygous).

Remarks. The history of the higher-level classification of

the Nepeidae is brief and vague. Whitehouse (1939)

erected the family, placing it in the Ptychopariina, but

did not discuss the classification any further, except to

mention that the group is closely related to the Ptycho-

pariidae. However, he did suggest that several genera,

including Acrocephalops, Alokistocare, Eldoradia and Bola-

spis, be placed in the Nepeidae, based primarily on the

possession of a preglabellar boss. Lochman-Balk (in Harr-

ington et al. 1959) elevated the Nepeidae to superfamilial

level (i.e. the Nepeacea), but with no justification. Loch-

man-Balk did not, however, recognize the genera that

Whitehouse (1939) considered members of the group,

therefore treating Nepea as being the sole representative

of the family, and indeed the superfamily. Opik (1963a)

reserved the use of Nepeacea, and gave a brief history of

the classification of the Nepeidae. Subsequently, Opik

(1967) regarded the Nepeacea as consisting of two famil-

ies, the Nepeidae and Menomoniidae, and suggested that

the genus Bolaspidella be transferred from the Menomo-

niidae to the Nepeidae. Opik (1970) later retained his

earlier views of the Nepeacea, and further suggested the

possible inclusion of the genus Periommella in the Nepei-

dae. I share the views of Robison (1988) and Pratt

(1992) in that the Nepeidae bears little in common with

the menomoniids, based on overall morphology, biogeog-

raphy and biostratigraphy, and that it should only

A B

C

TEXT -F IG . 8 . Multivariate scatterplots for the first four principal components in a pooled sample of Nepea cranidia from type-suite

and locality-based collections; n ¼ 20. A, principal component 1 (PC1) versus principal component 2 (PC2). B, principal component

2 (PC2) versus principal component 3 (PC3). C, principal component 3 (PC3) versus principal component 4 (PC4).

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 491

contain the genera Nepea, Penarosa, Loxonepea and Fer-

enepea.

The higher-level classification of the Nepeidae presented

here follows that of Fortey (1997) in placing the group

within the superfamily Ptychoparioidea. As discussed by

Fortey, the definition of the Ptychopariina is problematic,

arising from issues such as the conservative and intergra-

dational bauplan of taxa, and the absence of distinctive

morphological characters, stratigraphical and geographical

criteria that have resulted in excessive splitting, and a pro-

liferation of taxa with imprecise morphological definitions.

For these reasons, phylogenetic relationships within the

Ptychopariina are poorly understood. Therefore, it is best

to maintain a conservative approach when dealing with

groups (especially superfamilies and families) within the

Ptychopariina, at least until a comprehensive phylogenetic

treatment can be conducted.

Genus NEPEA Whitehouse, 1939

1939 Nepea Whitehouse, p. 211.

1963 Nepea Whitehouse; Opik, p. 313.

1959 Nepea Whitehouse; Lochman-Balk in Harrington et al.,

p. O251.

1970 Nepea Whitehouse; Opik, p. 9.

1970 Folliceps; Opik, p. 20.

Type species. Nepea narinosa Whitehouse, 1939, p. 212.

Other species. Nepea tonsillata Opik, 1970; Nepea nans (Opik,

1970); Nepea xinjiangensis Xiang and Zhang, 1985; Nepea brevica

Xiang and Zhang, 1985.

Revised diagnosis. Cranidium semicircular, length (sag.)

75 per cent post-palpebral cranidial width (tr.); glabella

gently tapered, width (tr.) at anterior margin 60 per cent

occipital ring width, glabellar length (sag.) 55 per cent

sagittal cranidial length, S1–S2 directed posteriorly, S3

directed laterally; lateral occipital lobes separated from

posterior cranidial border by shallow furrow; preglabellar

boss trapeziform; eye ridge slightly arched anteriorly,

directed slightly anteriorly abaxially.

Remarks. Comparison of Chinese species of Nepea erected

by Xiang and Zhang (1985), N. xinjiangensis and N. brev-

ica with Australian species is difficult because the Chinese

species represent small individuals, possibly early holaspid

stages, with the largest specimen having a maximum cra-

nidial length of 3 mm. Furthermore, N. xinjiangensis and

N. brevica are probably conspecific, based on their identi-

cal cranidial morphology and co-occurrence in the Ken-

say Formation. Further investigation of these species is

required, but that is not attempted here.

Nepea narinosa Whitehouse, 1939

Plate 1, figures 1–12; Plate 2, figures 1–8

v*1939 Nepea narinosa Whitehouse, p. 212, pl. 22, figs 15a–b,

16.

1959 Nepea narinosa Whitehouse; Lochman-Balk in Harr-

ington et al., p. O251, fig. 188.

v1970 Nepea narinosa Whitehouse; Opik, p. 9, pl. 1,

figs 1a)4; pl. 2, figs 1–6; pl. 3, fig. 1.

v1970 Nepea anoxys Opik, p. 14, pl. 3, fig. 4a–b.

v1970 Nepea exserta Opik, p. 15, pl. 4, figs 1–3.

v?1970 Nepea sp. NA Opik, p. 16, pl. 3, fig. 5.

v1970 Nepea sp. NB Opik, p. 17, pl. 3, fig. 3a–b.

v1970 Nepea sp. cf. exserta Opik, p. 17, pl. 3, fig. 2.

v1970 Nepea avara Opik, p. 18, pl. 6, figs 1a)5.

Holotype. UQF3335, internal mould of cranidium from the Split

Rock Sandstone, locality M417 (Pl. 1, fig. 1).

Other material. Thirty-nine cranidia: paratype, UQF3336;

CPC4740–4741, 7272–7274, 7276, 7278, 7280–7284, 7286–7289,

37065–37078, 37105–37111, 37115; three librigenae: CPC4742,

7275, 7277; one partial exoskeleton: CPC7279.

Revised diagnosis. Nepea with occipital ring not elevated

above glabella; dorsal elevation of palpebral lobe increas-

ing posteriorly; long intergenal spine positioned on the

posterolateral corner of the posterolateral projection,

length approximately 130 per cent of the sagittal cranidial

length; posterior border furrow deep, wide (exsag.), rap-

idly expanding at distal end of furrow.

EXPLANATION OF PLATE 1

Figs 1–12. Nepea narinosa Whitehouse, 1939. 1, UQF3335, holotype, internal mould of cranidium; M417; · 4Æ5. 2, UQF3336, paratype,

internal mould of cranidium; M417; · 3. 3, CPC4741, internal mould of cranidium, stereo pair, holotype of Nepea anoxys Opik,

1970; M417; · 3. 4, CPC7275, latex cast of external mould of librigena; M226; · 4Æ5. 5–7, CPC7284, internal mould of cranidium,

holotype of Nepea exserta Opik, 1970; M344. 5, dorsal view; · 3. 6, anterolateral view; · 3Æ5. 7, oblique lateral view; · 3Æ5. 8,

CPC7278, internal mould of cranidium; M226; · 6Æ5. 9–10, CPC7279, latex cast of external mould of partial exoskeleton; M276. 9,

dorsal view; · 4Æ5. 10, oblique lateral view; · 3. 11, CPC7280, internal mould of cranidium; Mail Change Limestone, O’Shannassy

River, Morstone, north-west Queensland; · 4Æ5. 12, CPC7277, latex cast of external mould of librigena; M226; · 5.

492 P A L A E O N T O L O G Y , V O L U M E 4 8

Description. Cranidium semicircular, length (sag.) averages 75

per cent post-palpebral cranidial width (J5); strongly convex

(sag. and tr.); anterior margin gently and evenly curved; poster-

ior margin straight to distally strongly posterolaterally directed.

Anterior branches of facial sutures moderately convergent to

anterior margin; posterior branches strongly divergent, curved

1 2

3 4

5

6 7

8

9

10

11

12

PLATE 1

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 493

PATERSON, Nepea

to distal end of posterolateral projection. Glabella gently

tapered, width (tr.) at anterior margin (K5) averages 60 per

cent occipital lobe width (K); moderately convex (sag.),

strongly convex (tr.); frontal lobe slightly rounded; glabellar

length (B1) (sag.) averages 55 per cent sagittal cranidial length.

Axial furrow shallow, deepening anteriorly; preglabellar furrow

deep across entire width, and wide (sag. and exsag.). Lateral

glabellar furrows deep, S1 strongly directed posteriorly at

approximately 30 degrees to axial furrow, S2 subparallel to,

and shorter (tr.) than S1, S3 directed laterally, and shorter (tr.)

than S2. Occipital ring not elevated above glabella, strongly

convex (tr.), length (sag.) averages 10 per cent glabellar length

(B1); short occipital spine with broad (tr.) base; posterior mar-

gin straight medially to slightly anteriorly directed laterally; lat-

eral parts of occipital lobe directed slightly anteriorly, separated

from posterior cranidial border by shallow furrow. S0 curved

slightly anteriorly, wide (sag.), shallow medially to deep later-

ally. Frontal area length (sag.) averages 45 per cent cranidial

length. Preglabellar field convex, downsloping anteriorly; medial

trapeziform boss strongly convex (sag. and tr.), dorsal surface

flattened to slightly rounded, occupying entire length (sag.) of

preglabellar field, length averages 35 per cent cranidial length,

widest (tr.) anteriorly and becoming narrower posteriorly,

maximum width (tr.) averages 50 per cent cranidial length.

Anterior border convex (sag. and exsag.), flattened dorsally,

slightly narrowing laterally, length (sag.) approximately 20 per

cent frontal area length. Anterior border furrow shallow. Fixi-

gena convex (tr.), preocular area strongly downsloping. Palpe-

bral lobe crescentic, length (exsag.) approximately 50 per cent

glabellar length (B1); anterior end located slightly anterior of

anterior margin of glabella, posterior end located opposite L2,

dorsal elevation of palpebral lobe increasing posteriorly; palpe-

bral furrow shallow. Eye ridge of moderate relief, slightly

arched anteriorly, bifurcates near axial furrow; eye ridge direc-

ted slightly anteriorly abaxially; proximal end connected to

frontal lobe, distal end separated from palpebral lobe by palpe-

bral furrow. Palpebral and postocular areas of fixigena down-

sloping adaxially. Baccula elliptical, moderately developed.

Posterolateral projection of fixigena strongly downsloping; long

intergenal spine positioned on the posterolateral corner of the

posterolateral projection, length approximately 130 per cent of

the sagittal cranidial length. Posterior border convex (exsag.),

moderately expanding distally; border furrow deep, wide (ex-

sag.), slightly directed posterolaterally, rapidly expanding at di-

stal end of furrow.

Librigena long and narrow, width averages 25 per cent length

with spine; lateral margin moderately curved. Genal field tra-

pezoidal, width averages 70 per cent librigenal width. Border

moderately convex (tr.), width averages 30 per cent librigenal

width; lateral border furrow deep and wide (tr.). Genal spine

with narrow base, curved adaxially, occupying approximately 40

per cent total length of librigena.

Rostral plate and hypostome unknown.

Thorax with at least 20 thoracic segments preserved on avail-

able specimen (CPC7279), moderately decreasing in width poste-

riorly. Axial furrows well defined, of moderate depth. Axial ring

width (tr.) approximately 65 per cent width of pleura. Thoracic

pleura projecting horizontally to fulcrum, then downward and

posterolaterally to distal end; pleural furrow short (exsag.); pleu-

ral end rounded.

Pygidium unknown.

Exoskeletal surface densely covered with granules, including

the dorsal surface of the palpebral lobes; frontal area of the cra-

nidium and genal field of librigena covered in genal caeca.

Remarks. Characters that Opik (1970) frequently used to

differentiate Nepea narinosa from other species of Nepea

include: (1) the size and shape of the preglabellar boss; (2)

size and structure of the palpebral lobes; and (3) the

development of the eye ridges. With regards to the size

and shape of the preglabellar boss in Nepea, bivariate ana-

lysis of the linear dimensions of the boss (PBL and PBW,

see Text-fig. 6G–H) has shown that the relative length and

width of the preglabellar boss cannot be used to discrim-

inate species; this apparent plasticity in the size of the boss

is the result of compaction. Opik (1970) differentiated

species of Nepea as either having a circular boss (e.g.

N. exserta, N. narinosa and N. tonsillata) or a trapezoidal

boss (e.g. N. anoxys and N. avara). However, in examin-

ing supplementary material from localities containing spe-

cies with a ‘circular boss’ sensu Opik (e.g. M417, M226,

M344), the majority of specimens exhibit a subtrapezoidal

boss. In fact, some specimens of N. narinosa illustrated by

Opik (1970, pl. 1, fig. 3; pl. 2, fig. 2; pl. 3, fig. 1) show a

subtrapezoidal boss. Therefore, the shape of the preglabel-

lar boss in Nepea shows significant intra- and interpopula-

tional variation, and hence is an unreliable diagnostic

character for species within the genus.

The palpebral lobes of species from Opik’s (1970) type-

suite do vary considerably; however, this variation can be

explained by factors of preservation and ontogeny. Opik

(1963a, 1970) described the unusual structure of the palp-

ebral lobe in Nepea narinosa, which he termed the ‘pixie

ear’. The palpebral lobe was given this name because the

anterior portion of the lobe is narrow and the posterior

portion of the lobe in many specimens slopes up abaxially

(Pl. 1, figs 8, 11). However, there are specimens from sev-

EXPLANATION OF PLATE 2

Figs 1–8. Nepea narinosa Whitehouse, 1939. 1–3, CPC4740, internal mould of cranidium; M417. 1, dorsal view; · 4. 2, anterolateral

view; · 3Æ5. 3, anterior view; · 4Æ5. 4–6, CPC37107, internal mould of cranidium; M344. 4, dorsal view; · 3Æ5. 5, anterolateral

view; · 5. 6, lateral view; · 5Æ5. 7, CPC7286, silicified cranidium, stereo pair, holotype of Nepea avara Opik, 1970; D108; · 5.

8, CPC7287, silicified cranidium, stereo pair; D108; · 6Æ5.

494 P A L A E O N T O L O G Y , V O L U M E 4 8

eral N. narinosa localities (including the type locality) that

do not display the ‘pixie ear’, but exhibit palpebral lobes

with narrow posterior ends, highly elevated perpendicular

to the fixigenal area. It is therefore conceivable that speci-

mens possessing ‘pixie ear’ palpebral lobes have been

compressed, causing the elevated posterior ends of the

1

2

3 4

5 6

7

8

PATERSON, Nepea

PLATE 2

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 495

lobes to become bent over. The relative size of the palpe-

bral lobe among species of Nepea is simply explained by

holaspid ontogeny. Because of the deformed nature or

absence of palpebral lobes in many specimens, it is not

possible to assess the growth pattern of the lobes bivari-

ately. However, in comparing the relative length of the

palpebral lobes with the overall length of the cranidium,

smaller specimens of Nepea possess large lobes, and larger

specimens display relatively smaller lobes, suggesting an

allometric growth pattern. It is unlikely that the palpebral

lobes are of taxonomic significance in Nepea.

Opik (1970) also utilized the structure of the eye ridges

to differentiate species of Nepea. Most of Opik’s species

(i.e. N. avara, N. exserta, N. narinosa and N. tonsillata)

possess eye ridges that are almost perpendicular to the

axial plane. However, Opik (1970, p. 18) differentiated

N. avara from other species by its ‘abaxially fading ocular

ridges’. The ‘fading’ of the abaxial portion of the eye

ridge in N. avara is simply a result of preservation. The

silicified type specimens from locality D108 illustrated by

Opik (1970, pl. 6, figs 1a–c, 2) display extensive beekite

rings on the surface, which commonly obscure details of

ornament in silicified fossils, suggesting that the eye rid-

ges may have been lost or diminished during silicification

(Pl. 2, figs 7–8). Furthermore, examination of specimens

illustrated by Opik (1970, pl. 6, figs 3–5) and supple-

mentary material from localities D54 and D95 show eye

ridges that extend from the anterolateral corners of

the glabella to the palpebral lobes, demonstrating that

N. avara does not possess eye ridges that ‘fade’ abaxially.

Opik distinguished N. anoxys from other species of Nepea

by its oblique eye ridges with divergent branches (Pl. 1,

fig. 3). Unfortunately, the holotype of N. anoxys

(CPC4741) is the only specimen of this species, thus mak-

ing observations of intraspecific variation impossible.

However, the type locality of N. anoxys is also the type

locality for N. narinosa (i.e. M417), and no other speci-

mens from locality M417 display oblique eye ridges with

divergent branches. The holotype of N. anoxys also has a

flattened appearance, implying that the eye ridges have

been skewed during compaction. Therefore, N. anoxys is

undoubtedly a synonym of N. narinosa.

Placement of Nepea sp. NA in synonymy with N. nari-

nosa is speculative. The bivariate analysis reveals that

Nepea sp. NA exhibits a slightly more tapered glabella

and narrower (tr.) preglabellar boss than in other species

of Nepea. Unfortunately, the posterior cranidial border of

Nepea sp. NA (Opik 1970, pl. 3, fig. 5) is poorly pre-

served and possibly flattened, and the distal portions of

the posterolateral projections of the fixigena are covered

by chert, thus making comparisons with other species

impossible.

Opik (1970) noted that the long glabella and short

frontal area distinguished Nepea sp. NB from N. narinosa,

but bivariate analysis does not support this assertion (see

Text-fig. 6A). As a consequence, Nepea sp. NB is placed

in synonymy with N. narinosa.

Stratigraphical occurrence. Middle Cambrian (Undillan–Boomer-

angian). Doryagnostus deltoides Zone, V-Creek Limestone, local-

ity M41. Goniagnostus nathorsti Zone, Split Rock Sandstone,

localities M133, M141, M226, M276, M344, M417, M421. Lejo-

pyge laevigata Zone, Steamboat Sandstone, localities D54, D95,

D108.

Nepea tonsillata Opik, 1970

Text-figure 9A–D

v*1970 Nepea tonsillata Opik, p. 15, pl. 5, figs 1–3.

Holotype. CPC7285, cranidium from the V-Creek Limestone,

locality M54 (Text-fig. 9A–D).

Revised diagnosis. Nepea with occipital ring elevated

above remainder of glabella; dorsal elevation of palpebral

lobe uniform from anterior to posterior; short intergenal

spine positioned on the posterior cranidial border posteri-

orly adjacent to the distal end of the posterior border fur-

row, length equal to sagittal length of glabella; posterior

border furrow deep, wide (exsag.), weakly expanding at

distal end of furrow.

Remarks. Although the holotype of N. tonsillata

(CPC7285) represents the only specimen of this species,

the position of the intergenal spine in this specimen dif-

fers significantly from specimens of N. narinosa as to war-

rant specific differentiation. The intergenal spine in

N. tonsillata is positioned on the posterior cranidial bor-

der posteriorly adjacent to the distal end of the posterior

border furrow, whereas the intergenal spine in N. narin-

osa is positioned on the posterolateral corner of the post-

erolateral projection. Moreover, the length of the

intergenal spine in N. tonsillata (see Text-fig. 9B–C) is

considerably shorter than that of N. narinosa (see Pl. 1,

fig. 5; Pl. 2, figs 1–2, 4–5). Examination of the holotype

of N. tonsillata shows that the intergenal spine tapers

enough to indicate that its total length would be equal to

that of the glabellar length (sag.), whereas in N. narinosa

the length of the intergenal spine is 130 per cent of the

sagittal cranidial length.

Stratigraphical occurrence. Middle Cambrian (Undillan). Ptychag-

nostus punctuosus–Goniagnostus nathorsti zones, V-Creek Lime-

stone, locality M54.

496 P A L A E O N T O L O G Y , V O L U M E 4 8

Nepea nans (Opik, 1970)

Text-figure 9E–G

v*1970 Folliceps nans Opik, p. 20, pl. 7, figs 1–3.

Holotype. CPC7290, cranidium from the Currant Bush Lime-

stone, locality M123 (Text-fig. 9E).

Other material. Two cranidia: CPC7291–7292.

Revised diagnosis. Nepea with occipital ring not elevated

above glabella; dorsal elevation of palpebral lobe uniform

from anterior to posterior; intergenal spine absent; pos-

terior border furrow deep, wide (exsag.), rapidly expand-

ing at distal end of furrow.

Remarks. Opik (1970) was consistent in referring to mor-

phological features of Folliceps nans as being ‘Nepea-like’.

In his generic diagnosis, Opik (1970, p. 20) stated that

‘Folliceps refers to Nepeidae with a narrow rim [¼ anter-

ior border] and obtuse cranidial front similar to Nepea,

but distinguished by simple, crescentic palpebral lobes,

and by the absence of intergenal spines’. These character-

istics can most certainly be observed in specimens of

F. nans; however, it is unlikely that they are of generic

importance, and more likely represent interspecific differ-

ences. As noted by Opik (1970, p. 21) in his comments

on illustrated specimens, F. nans exhibits a similar pregla-

bellar boss and anterior border to that of Nepea. Exam-

ination of available specimens also reveals that both these

species have very similar glabellar morphology. Inclusion

of F. nans in the bivariate and multivariate analyses of

Nepea illustrates that the linear dimensions assessed can-

not differentiate these taxa. Based on the available mater-

ial, the only major difference between F. nans and species

of Nepea is the presence of intergenal spines in the latter.

Therefore, Folliceps is herein considered a junior subject-

ive synonym of Nepea, and F. nans represents a valid

species of Nepea.

Stratigraphical occurrence. Middle Cambrian (Late Templeto-

nian ⁄ Floran). Euagnostus opimus Zone, Currant Bush Limestone,

localities M123 and M124.

A B

C DE

F G

TEXT -F IG . 9 . A–D, Nepea tonsillata Opik, 1970, CPC7285, holotype, testate cranidium; M54. A, dorsal view, stereo pair; · 4. B,

lateral view; · 6. C, anterolateral view; · 4Æ5. D, anterior view; · 4. E–G, Nepea nans (Opik, 1970). E, CPC7290, holotype, latex cast of

external mould of cranidium; M123; · 8. F, CPC7291, silicified cranidium, stereo pair; M124; · 5Æ5. G, CPC7292, latex cast of external

mould of cranidium; M123; · 4.

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 497

Genus PENAROSA Opik, 1970

1970 Penarosa Opik, p. 24.

1972 Trinepea Palmer and Gatehouse, p. D25.

1977 Penarosa Opik; Jell, p. 119.

1978 Penarosa Opik; Jell and Robison, p. 17.

Type species. Penarosa retifera Opik, 1970, p. 25.

Other species. Penarosa elaticeps Opik, 1970; Penarosa rhinodel-

phis Opik, 1970; Penarosa trinodus (Palmer and Gatehouse,

1972); Penarosa netenta Jell, 1977.

Revised diagnosis. Cranidium trapeziform or subtriangu-

lar, length (sag.) 95 per cent post-palpebral cranidial width

(tr.); glabella gently tapered, width (tr.) at anterior margin

75 per cent occipital ring width, glabellar length (sag.) 50

per cent cranidial length, S1 and S2 directed posteriorly,

S3 directed anteriorly; lateral occipital lobes separated

from posterior cranidial border by shallow or deep furrow;

preglabellar boss subtriangular; eye ridge slightly arched

anteriorly, almost perpendicular to axial line.

Remarks. Jell (1977, p. 119) discussed the taxonomic sta-

tus of Trinepea, concluding that it is a junior synonym of

Penarosa. The morphogenesis of Penarosa has been des-

cribed in detail by Opik (1970, pp. 43–44) and will not

be elaborated upon here.

Penarosa retifera Opik, 1970

Plate 3, figures 1–12; Text-figure 10A–E

v*1970 Penarosa retifera Opik, p. 25, pl. 8, figs 1a)2b; pl. 9,

figs 1–2, 4.

v1970 Penarosa sp. PA aff. retifera Opik, p. 29, pl. 9, fig. 5a–

b.

v1970 Penarosa vittata Opik, p. 29, pl. 10, fig. 2; pl. 15,

figs 1a)2.

v1970 Penarosa sp. PB aff. vittata Opik, p. 30, pl. 15, fig. 3.

v1970 Penarosa petalifera Opik, p. 37, pl. 11, fig. 4; pl. 16,

figs 1a–c, 3a)5; p. 38, text-fig. 13.

v1970 Penarosa melota Opik, p. 40, pl. 14, fig. 1a–b.

v1970 Penarosa sp. nov. PD aff. vittata Opik, p. 42, pl. 7,

fig. 6.

v1970 Penarosa sp. nov. PE Opik, p. 42, pl. 7, fig. 7.

1978 Penarosa retifera Opik; Jell and Robison, p. 17, pl. 4,

figs 17–19.

Holotype. CPC7297, cranidium from the Currant Bush Lime-

stone, locality M180 (Pl. 3, figs 1–6).

Other material. Forty-eight cranidia: CPC7295–7296, 7298–7299,

7302–7303, 7312, 7316, 7319–7322, 7324–7326, 7333–7335,

37079, 37091–37093, 37095–37104, 37116–37118, 37120–37126,

37128–37129, 37132–37136; seven librigenae: CPC7304–7305,

37094, 37119, 37127, 37130–37131; two partial exoskeletons:

CPC7300, 7318.

Revised diagnosis. Penarosa with trapeziform cranidium;

short posteromedial occipital spine with broad (tr.) base;

lateral occipital lobe separated from posterior cranidial

border by shallow furrow; baccula elliptical, moderately

developed, length (exsag.) equal to length of L1; anterior

border moderately to strongly concave, strongly upturned,

narrows laterally; anterior border furrow very shallow and

poorly defined; posterior border furrow narrow (exsag.),

less than width (sag.) of occipital ring. Cranidial surface,

except for the palpebral lobes and posterior border fur-

row, covered in granules of varying sizes; glabella and

occipital ring densely covered in small granules; proximal

portion of palpebral and postocular areas of fixigena cov-

ered in moderately spaced, medium-sized granules,

becoming smaller and more closely spaced abaxially; post-

erolateral projection of fixigena covered in small granules

and genal caeca; frontal area evenly covered in small and

medium-sized granules and genal caeca.

Description. Cranidium trapeziform, length (sag.) averages 95

per cent post-palpebral cranidial width (J5); strongly convex

(sag. and tr.); anterior margin moderately and evenly curved;

posterior margin straight, distally strongly posterolaterally

directed. Anterior branches of facial sutures subparallel to

about level with midlength of frontal area (exsag.), then con-

vergent to anterior margin; posterior branches strongly diver-

gent, curved to distal end of posterolateral projection then

moderately convergent to posterior margin. Glabella gently

tapered, width (tr.) at anterior margin (K5) averages 75 per

cent occipital lobe width (K); moderately convex (sag.),

strongly convex (tr.); frontal lobe bluntly rounded; glabellar

length (B1) (sag.) averages 50 per cent cranidial length. Axial

furrow deep, shallower posteriorly, and wide (tr.); preglabellar

EXPLANATION OF PLATE 3

Figs 1–12. Penarosa retifera Opik, 1970. 1–6, CPC7297, holotype, testate cranidium; M180. 1, dorsal view, stereo pair; · 2. 2, lateral

view; · 2Æ5. 3, oblique lateral view; · 2. 4, anterior view; · 2Æ5. 5, anterolateral view; · 2. 6, enlargement of glabella; · 4. 7,

CPC7304, testate librigena; M180; · 3. 8–10, CPC7300, testate partial exoskeleton; M393. 8, dorsal view; · 2. 9, enlargement

of articulated axial rings; · 4Æ5. 10, enlargement of articulated pleurae; · 4. 11, CPC7298, testate cranidium, stereo pair;

M186; · 3. 12, CPC7316, testate cranidium, stereo pair, holotype of Penarosa melota Opik, 1970; M124; · 3Æ5.

498 P A L A E O N T O L O G Y , V O L U M E 4 8

furrow moderately deep across entire width with pit developed

at midpoint, and wide (sag. and exsag.). Lateral glabellar fur-

rows deep, S1 directed posteriorly at approximately 45 degrees

to axial furrow, S2 parallel to and shorter (tr.) than S1, S3

directed anteriorly at approximately 45 degrees to axial furrow

and is slightly shorter (tr.) than S2. Occipital ring not elevated

1

2 3

4 5 6

7

8

9 10

11

12

PLATE 3

PATERSON, Penarosa

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 499

above remainder of glabella, strongly convex (tr.), length (sag.)

averages 15 per cent glabellar length (B1); short posteromedial

occipital spine with broad (tr.) base; posterior margin straight

medially and slightly anteriorly directed laterally; lateral parts

of occipital lobe directed slightly anteriorly, separated from

posterior cranidial border by shallow furrow. S0 curved slightly

anteriorly medially, wide (sag.), shallow medially to deep later-

ally. Frontal area length (sag.) averages 50 per cent cranidial

length (sag.). Preglabellar field convex, strongly anteriorly

downsloping, length (sag.) averages 60 per cent frontal area

length; medial subtriangular boss of moderate relief occupying

entire length (sag.) of preglabellar field, slightly extending onto

anterior border, posterior width slightly narrower (tr.) than

anterior glabellar width (K5), slightly tapering anteriorly. Anter-

ior border moderately to strongly concave, strongly upturned,

moderately narrowing laterally, length (sag.) averages 35 per

cent frontal area length. Anterior border furrow very shallow

and poorly defined. Fixigena moderately convex (tr.), preocular

area strongly downsloping. Palpebral lobe reniform, length (ex-

sag.) 50 per cent glabellar length (B1), width approximately 40

per cent lobe length; anterior end located opposite frontal lobe,

posterior end located opposite S1 or L1; palpebral furrow

moderately deep. Eye ridge of moderate relief, slightly arched

anteriorly, bifurcates near axial furrow; almost perpendicular to

sagittal line; proximal end separated by shallow axial furrow,

distal end separated from palpebral lobe by palpebral furrow.

Palpebral and postocular areas of fixigena downsloping adaxial-

ly. Baccula elliptical, moderately developed, length (exsag.)

equal to length of L1. Posterolateral projection of fixigena very

strongly downsloping, rapidly expanding abaxially. Posterior

border convex (exsag.), widens rapidly abaxially and is strongly

directed posterolaterally where the posterior border furrow

becomes shallow, and is then directed anteriorly at the distal

end of the posterolateral projection; posterior border furrow

deep, slightly directed posterolaterally, expanding abaxially, then

becomes shallow where posterior border becomes strongly

A

B

C

D E

TEXT -F IG . 10 . Penarosa retifera Opik, 1970. A–C, CPC7318, testate partial exoskeleton, holotype of Penarosa vittata Opik, 1970;

M124. A, dorsal view, stereo pair; · 2Æ5. B, enlargement of cranidium; · 3. C, enlargement of articulated thoracic segments; · 5. D,

CPC37116, testate cranidium, stereo pair; GF1; · 2Æ5. E, CPC37094, testate librigena; M180; · 4Æ5.

EXPLANATION OF PLATE 4

Figs 1–12. Penarosa elaticeps Opik, 1970. 1–4, CPC7311, holotype, testate cranidium. 1, dorsal view, stereo pair; · 2Æ5. 2, oblique lateral

view; · 3. 3, anterior view; · 3. 4, anterolateral view; · 2Æ5. 5, CPC7306, latex cast of external mould of partial exoskeleton;

· 3Æ5. 6–9, CPC7310, testate cranidium, holotype of Penarosa zeabunda Opik, 1970. 6, dorsal view, stereo pair; · 4Æ5. 7,

oblique lateral view; · 5. 8, anterior view; · 4Æ5. 9, anterolateral view; · 3Æ5. 10, CPC7309, testate cranidium, stereo pair;

· 6Æ5. 11, CPC7331, internal mould of meraspid cranidium; · 12Æ5. 12, CPC7332, internal moulds of meraspid cranidia;

· 11. All specimens from locality M179.

500 P A L A E O N T O L O G Y , V O L U M E 4 8

directed posterolaterally and continues parallel to the posterior

margin until it curves anteriorly to merge with the lateral mar-

gin of the posterolateral projection.

Librigena long and narrow, width averages 25 per cent length

with spine; lateral margin strongly curved; inner (sutural) mar-

gin between librigenal field and genal spine with large rounded

1 2

3 4

5

6

7 8

9

10

11

12

PLATE 4

PATERSON, Penarosa

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 501

embayment to accommodate the posterolateral projection of the

fixigena. Anterior part of dorsal surface developed as narrow

projection. Genal field trapezoidal, moderately convex, width

(tr.) averages 80 per cent librigenal width. Border flat to slightly

concave, width averages 20 per cent librigenal width; lateral bor-

der furrow very shallow and poorly defined. Genal spine with

narrow base, curved adaxially, occupying approximately 45 per

cent total length of librigena. Doublure wider anteriorly than

border.

Rostral plate and hypostome unknown.

Thorax with at least 26 thoracic segments preserved, moder-

ately decreasing in width posteriorly. Axial furrows well defined,

of moderate depth. Axial ring width (tr.) approximately 45 per

cent width of pleura on each thoracic segment, strongly convex

(tr.), straight medially to anterolaterally directed laterally; articu-

lating half ring relatively short (sag.), length slightly less than

that of axial ring, posterior margin straight; articulating furrow

well developed, wide (sag. and exsag.), lateral portion deepened

into an apodemal pit. Thoracic pleura projecting horizontally to

fulcrum, then downward and posterolaterally to distal end;

anterior pleural band of uniform width (exsag.) to fulcrum, then

expanding abaxially to pleural end; posterior pleural band of

uniform and equal width (exsag.) as anterior pleural band to ful-

crum, then expanding abaxially and becoming considerably

wider (exsag.) than the anterior pleural band at the pleural end;

pleural end bluntly pointed; pleural furrow moderately deep,

long (exsag.), uniform width to fulcrum, then tapering abaxially,

not quite reaching the pleural end.

Pygidium unknown.

Exoskeletal surface covered with granules of varying sizes;

palpebral lobes and posterior border furrow on the cranidium,

and the pleural furrows on the thoracic segments are smooth.

Glabella and occipital ring densely covered in small granules;

proximal portion of palpebral and postocular areas of fixigena

covered in moderately spaced, medium-sized granules, becoming

smaller and more closely spaced abaxially; posterolateral projec-

tions covered in small granules and genal caeca; frontal area

evenly covered in small and medium-sized granules and an anas-

tomosing network of genal caeca. Librigenal field densely cov-

ered in small and medium-sized granules and genal caeca;

librigenal border and spine covered with small, well-spaced gran-

ules. Axial ring and the anterior and posterior pleural bands of

the thoracic segments covered in small and medium-sized gran-

ules.

Remarks. Opik (1970) mentioned that Penarosa vittata

was closely related to P. retifera, but could be distin-

guished by its moderately vaulted cephalon, small

posterolateral projections, wide interocular cheeks,

absence of caeca on the anterior border, and the pres-

ence of a transverse ridge on the posterior part of the

anterior border. Specimens of P. vittata have been

slightly compressed, explaining why cranidia are moder-

ately vaulted. Moreover, compression of specimens also

provides an explanation for the transverse ridges in

P. vittata. Examination of specimens shows no evidence

of a ridge, but specimens display transverse kinks across

the anterior border as a result of compression (Text-

fig. 10B), creating the illusion of a ridge-like structure.

Furthermore, genal caeca are most certainly present on

the anterior border. Comparison of the posterolateral

projections of specimens of P. vittata with specimens of

equal size from locality M180 show no discernible differ-

ences in length or width. Bivariate analysis has demon-

strated that P. vittata and P. retifera cannot be

distinguished with regard to the relative width of the

‘interocular cheeks’ (i.e. post-palpebral cranidial width).

Lastly, P. vittata possesses a very short occipital spine,

moderately developed bacculae, lateral occipital lobes

separated from the posterior cranidial border by a shal-

low furrow, and has a pattern of ornamentation on the

cranidium identical to that of P. retifera. Therefore,

based on this evidence, P. vittata is herein considered a

junior subjective synonym of P. retifera.

Opik (1970) differentiated Penarosa petalifera from

P. retifera (and indeed the majority of other species of

Penarosa) by its ‘short’ frontal area. However, bivariate

analysis has demonstrated that species of Penarosa cannot

be distinguished on the relative length of the frontal area.

Opik also emphasized the ‘petaliform’ occipital spine as

a diagnostic character in P. petalifera. This unusual fea-

ture is obvious in the holotype of P. petalifera

(CPC7322); however, the ‘petaliform’ occipital spine is

less prominent in any other specimen of P. petalifera that

has the occipital ring preserved. Furthermore, the holo-

type of P. retifera exhibits a small occipital spine with a

broad (tr.) base, similar in shape to that of P. petalifera.

As the holotype of P. petalifera is less than half the size

of the holotype of P. retifera, it is possible that the for-

mer specimen represents a developmental stage in the

occipital spine, implying that the occipital spine displays

strong negative allometry during growth. Opik (1970)

EXPLANATION OF PLATE 5

Figs 1–12. Penarosa rhinodelphis Opik, 1970. 1–4, CPC7314, holotype, testate cranidium. 1, dorsal view, stereo pair; · 3Æ5. 2, lateral

view; · 4. 3, anterior view; · 5. 4, anterolateral view; · 4. 5, CPC37087, testate cranidium and partial exoskeleton; · 6Æ5. 6–9,

CPC7315, testate cranidium. 6, dorsal view, stereo pair; · 6. 7, oblique lateral view; · 6Æ5. 8, anterior view; · 8. 9,

anterolateral view; · 5Æ5. 10, CPC37083, testate cranidium; · 4Æ5. 11–12, CPC7313, testate cranidium, holotype of Penarosa

meniscops Opik, 1970. 11, dorsal view, stereo pair; · 3Æ5. 12, lateral view; · 4Æ5. All specimens from locality M179.

502 P A L A E O N T O L O G Y , V O L U M E 4 8

also noted that the S3 furrows in P. petalifera are devel-

oped as isolated pits and not connected to the axial gla-

bellar furrow. However, in no specimens are the L3 lobes

and lateral projections of the frontal lobe connected. The

above evidence suggests that P. petalifera and P. retifera

are synonymous.

1

2

3 4

5

6 7

8 910

11 12

PLATE 5

PATERSON, Penarosa

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 503

Opik (1970) used several characters to differentiate

Penarosa melota from other species of Penarosa. He

emphasized the narrow interocular cheeks, frontal area

length, anterior glabellar width, and occipital lobe width

as distinguishing features of the species; the bivariate ana-

lysis does not support this interpretation. Opik (1970,

p. 40) also used the ‘slender (not petaliform) occipital

spine’ as an additional diagnostic feature of P. melota.

However, examination of the holotype shows that the

occipital spine has a broad base, further supporting syn-

onymy with P. retifera.

Opik (1970) differentiated Penarosa sp. PA aff. reti-

fera, Penarosa sp. PB aff. vittata, Penarosa sp. nov. PD

aff. vittata and Penarosa sp. nov. PE based on linear

dimensions among other features. Inclusion of these spe-

cies in the bivariate and multivariate analyses demon-

strated that they cannot be distinguished by means of

the linear characters assessed. Opik (1970) also empha-

sized non-linear characters in these species; however,

many of these can be attributed to misinterpretation or

differences in preservation. For example, Opik noted

that Penarosa sp. PB aff. vittata and Penarosa sp. nov.

PD aff. vittata exhibit a transverse ridge on the anterior

border like that of P. vittata; however, these ridges rep-

resent kink structures resulting from compression, as is

the case for specimens of P. vittata. The only specimen

of Penarosa sp. PB aff. vittata (CPC7320) also displays

weakly impressed intercalated furrows on the lateral pro-

jections of the frontal lobe of the glabella; however, this

is common in some specimens of P. retifera. In the only

specimen of Penarosa sp. nov. PE (CPC7296), Opik only

recorded two pairs of glabellar furrows; however, close

examination of this specimen clearly shows three pairs

of glabellar furrows.

Opik (1970) observed four glabellar furrows in P. reti-

fera and the majority of other species of Penarosa;

however, examination of the holotype of P. retifera and

supplementary material from the type locality M180

shows that the majority of specimens do not exhibit

distinct S4 furrows or L4 lobes on the glabella. Some

specimens of Penarosa exhibit a diminutive depression

in one or both sides of the lateral projection of the

frontal lobe of the glabella (Pl. 3, figs 6, 11; Pl. 4,

figs 1, 6; Pl. 6, fig. 7), which may be interpreted as a

poorly developed intercalated furrow; however, this fea-

ture is not consistent in all specimens. Hughes (1993,

1994) has noted that intercalated furrows are common

in slightly compressed specimens; however, some speci-

mens of P. retifera that exhibit these intercalated fur-

rows show no obvious signs of compression. So,

because of their intermittent occurrence, it is unlikely

that the intercalated furrows in some specimens of

P. retifera and other species of Penarosa are of taxo-

nomic significance.

Jell (1977, p. 122) convincingly demonstrated that the

pygidium attributed to Penarosa retifera by Opik (1970,

p. 28, text-fig. 11; pl. 9, fig. 3) was incorrectly assigned,

and that it does not belong to the Nepeidae at all.

Comparison of the pygidium of P. netenta (QMF7062)

and that assigned to P. retifera by Opik (1970)

(CPC7301) shows that the overall morphology of the

two pygidia differ markedly. Firstly, the pygidium of

P. netenta is approximately 40 per cent as long as wide,

whereas specimen CPC7301 is around 75 per cent as

long as wide. Secondly, the pygidial axis of P. netenta is

60 per cent as wide as the pygidium at the midlength

of the axis, whereas in specimen CPC7301 this propor-

tion is only 33 per cent. The pygidium of P. netenta

can be differentiated further by its smooth pleural field

and absence of a border, whereas specimen CPC7301

possesses well-developed pleural ribs and a well-defined

border. Jell (1977) also discussed the similarity of the

pygidium of P. netenta to that of an undescribed species

of Nepea from Christmas Hills, north-west Tasmania; a

latex cast of the latter species was provided by Dr Jim

Jago to Dr Peter Jell for examination. Dr Jago has sub-

sequently provided me with photographs of a different

species from Native Track Tier, north-west Tasmania. I

concur with Jell (1977) that the pygidia of species of

Nepea are almost identical to that of P. netenta, repre-

senting very small simple plates, thus supporting the

conclusion that the pygidium illustrated by Opik

(1970) does not belong to P. retifera or any other

nepeid species.

The librigena assigned to Penarosa petalifera by Opik

(1970, pl. 16, fig. 2) is dubious. Opik (1970, p. 37)

noted in his description that ‘neither a rostral shield

nor a medial suture is present’. This is an unusual con-

dition for librigenae in Penarosa, because isolated librig-

enae of P. retifera and P. netenta exhibit sutural

terminations on the ventral doublure and anterior end

of the dorsal surface. Furthermore, it has been demon-

strated above that the cranidia of P. petalifera and

P. retifera are indistinguishable, and hence there is no

reason to believe the librigenae of these species should

differ in any way. Close examination of the librigenal

unit (CPC7323) shows no evidence of ventral sutures;

thus, it is unlikely that this specimen belongs to a spe-

cies of Penarosa.

Stratigraphical occurrence. Middle Cambrian (Late Templeto-

nian ⁄ Floran–Undillan). Acidusus atavus Zone, Arthur Creek

Formation, locality H4. Euagnostus opimus Zone, Age Creek

Formation, localities M157 and M160; Gowers Formation,

locality GF1; Currant Bush Limestone, localities M123,

M124, M180, M186, M393, UQL256, UQL463. Ptychagnostus

punctuosus Zone, Currant Bush Limestone, localities M28,

M130.

504 P A L A E O N T O L O G Y , V O L U M E 4 8

Penarosa elaticeps Opik, 1970

Plate 4, figures 1–2

v*1970 Penarosa elaticeps Opik, p. 34, pl. 11, fig. 3; pl. 12,

fig. 2a–d.

v1970 Penarosa zeabunda Opik, p. 31, pl. 10, figs 3–5; pl. 11,

figs 1a)3; pl. 12, fig. 1; pl. 17, figs 5–6; p. 33, text-

fig. 12.

Holotype. CPC7311, cranidium from the Currant Bush Lime-

stone, locality M179 (Pl. 4, figs 1–4).

Other material. Ten cranidia: CPC7307–7310, 7331–7332, 37080,

37082, 37088, 37090; one partial exoskeleton: CPC7306.

Revised diagnosis. Penarosa with trapeziform cranidium;

occipital spine absent; lateral occipital lobe separated

from posterior cranidial border by shallow furrow; baccu-

la subcircular, moderately well developed, length (exsag.)

slightly longer than L1; anterior border convex (sag. and

exsag.), moderately upturned, narrowing laterally; anterior

border furrow wide (sag.) and shallow; posterior border

furrow narrow (exsag.), less than width (sag.) of occipital

ring. Cranidial surface except for the palpebral lobes, pos-

terior border and border furrow covered in evenly spaced,

small and medium-sized granules; frontal area and post-

erolateral projection of fixigenae covered in genal caeca.

Remarks. Apart from linear dimensions that can be disre-

garded based on results of the morphometric analysis,

Opik (1970) differentiated P. zeabunda and P. elaticeps by

observing a ‘retral recess’ in the medial anterior border of

the latter species. However, examination of the holotype

specimen of P. elaticeps (Pl. 4, figs 1–4) shows no such

feature, as is the case for all other specimens from locality

M179. The ‘retral recess’ in the holotype of P. elaticeps

appears to be a misinterpretation of an illustration of the

specimen by Opik (1970, pl. 11, fig. 3). The oblique an-

terodorsal view at which the specimen was photographed

shows that the apparent ‘retral recess’, in fact, represents

the upturned nature of the cranidial border (Opik 1970,

pl. 12, fig. 2b–c). Opik (1970) also noted that the post-

erolateral projections of the fixigena are not strongly

downsloping in P. elaticeps as in other species of Penaro-

sa. This is easily explained by compaction of the individ-

ual as the posterolateral projections are asymmetrically

disposed and there are signs of breakage of the sclerite.

The meraspid cranidia of Penarosa zeabunda illustrated

by Opik (1970, p. 33, text-fig. 12; pl. 17, figs 5–6; see also

Pl. 4, figs 11–12) most likely belong to this species and

not to P. rhinodelphis (the other valid species from local-

ity M179), as they possess a relatively narrow (sag.) and

long (tr.) anterior border, like that of holaspid cranidia

of P. elaticeps. As shown in the bivariate analysis, small

holaspid cranidia of P. rhinodelphis display a very wide

(sag.) and short (tr.) anterior border.

Stratigraphical occurrence. Middle Cambrian (Late Templeto-

nian ⁄ Floran). Acidusus atavus Zone, Currant Bush Limestone,

locality M179.

Penarosa rhinodelphis Opik, 1970

Plate 5, figures 1–2

v*1970 Penarosa rhinodelphis Opik, p. 34, pl. 13, figs 1a)2c.

v1970 Penarosa meniscops Opik, p. 36 (partim), pl. 12,

fig. 3a–b (non pl. 14, fig. 2).

Holotype. CPC7314, cranidium from the Currant Bush Lime-

stone, locality M179 (Pl. 5, figs 1–4).

Other material. Six cranidia: CPC7313, 7315, 37083, 37085–

37087.

Revised diagnosis. Penarosa with subtriangular cranidium;

short posteriorly located occipital spine with broad (tr.)

base; lateral occipital lobe separated from posterior crani-

dial border by shallow furrow; baccula elliptical, large,

very well developed, longer than L1 (exsag.); anterior bor-

der subtriangular in outline, convex (sag.), strongly

upturned; anterior border furrow wide (sag.) and shallow;

posterior border furrow narrow (exsag.), less than width

(sag.) of occipital ring. Cranidial ornament identical to

P. elaticeps.

Remarks. The holotype specimen of Penarosa meniscops is

placed in synonymy with P. rhinodelphis primarily based

on possession of a convex (sag.), strongly upturned,

subtriangular anterior border and large, well-developed

bacculae. Opik (1970, p. 35) distinguished P. meniscops

from P. rhinodelphis by its ‘continuous frontal marginal

furrow, snoutless front and wide span of the frontal arc [i.e.

anterior border]’. Differences between these three features

most likely represent intraspecific ontogenetic variation. As

demonstrated in the bivariate analysis, dimensions of the

anterior border (i.e. length and width) in P. rhinodelphis

and P. meniscops (plus three other specimens from M179)

show continuous variation during growth (see Text-fig. 5).

This ontogenetic variation is also evident in the anterior

border furrow, with the furrow in some smaller specimens

being poorly developed medially (Pl. 5, figs 6, 10), and lar-

ger specimens displaying well-developed furrows along the

entire width of the border (Pl. 5, fig. 11).

Stratigraphical occurrence. Middle Cambrian (Late Templeto-

nian ⁄ Floran). Acidusus atavus Zone, Currant Bush Limestone,

locality M179.

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 505

Penarosa netenta Jell, 1977

Plate 6, figures 1–9

v1970 Penarosa meniscops Opik, p. 36 (partim), pl. 14, fig. 2

(non pl. 12, fig. 3a–b).

v1970 Penarosa sp. nov. PC Opik, p. 40, pl. 17, figs 3–4;

p. 41, text-fig. 14.

v*1977 Penarosa netenta Jell, p. 119, pl. 21, figs 1a)8.

Holotype. QMF7059, cranidium from locality QML152 (Pl. 6,

fig. 1).

Other material. Paratypes: QMF7060–7070; supplementary

material: QMF7371–7376; CPC7317, 7329–7330, 37112–37114.

Revised diagnosis. Penarosa with trapeziform cranidium;

slender, needle-like posteriorly located occipital spine

without broad (tr.) base; lateral occipital lobe separated

from posterior cranidial border by deep furrow; baccula

elliptical, moderately well developed, length (exsag.) equal

to length of L1; anterior border flat to moderately con-

cave (sag.), moderately upturned, moderately narrowing

laterally; anterior border furrow wide (sag.) and shallow;

posterior border furrow wide (exsag.), greater than or

equal to width (sag.) of occipital ring. Exoskeletal orna-

ment similar to P. retifera, but differs in displaying coar-

ser granules on the glabella, proximal portion of palpebral

and postocular areas of the fixigenae, and frontal area.

Remarks. Penarosa netenta can be clearly distinguished

from other species of Penarosa by its lateral occipital

lobes being clearly separated from the posterior cranidial

border by a deep furrow, in addition to its wide (exsag.)

posterior border furrow and coarse ornamentation.

Examination of a specimen of P. meniscops (CPC7317)

illustrated by Opik (1970, pl. 14, fig. 2) shows an

identical condition of the occipital lobes, in addition to a

similar anterior border, anterior border furrow, and pos-

terior border furrow to those in P. netenta. Furthermore,

specimen CPC7317 comes from locality M412 of Opik

(1970), which is in close proximity to Jell’s (1977) localit-

ies of the Chummy Bore Formation. Although Opik

(1970) referred to the stratigraphical unit at locality M412

as the Inca Formation, the lithologies in which P. netenta

and specimens from M412 occur are identical, and thus

the Chummy Bore Formation (sensu Jell 1977) and Inca

Formation (sensu Opik 1970) probably represent the same

stratigraphical unit. Jell (1977) noted that Penarosa sp.

nov. PC is probably conspecific with P. netenta, but that

Opik’s (1970) figured specimens did not allow complete

confidence in this assertion. Examination of Penarosa sp.

nov. PC specimen CPC7329 illustrated by Opik (1970,

pl. 17, fig. 3; p. 41, text-fig. 14) shows a similar anterior

border to P. netenta, in addition to its coarse ornamenta-

tion. Unfortunately the occipital ring of specimen

CPC7329 is not sufficiently preserved for comparison.

However, the occurrence of Penarosa sp. nov. PC at local-

ity M412 further supports synonymy with P. netenta.

Stratigraphical occurrence. Middle Cambrian (Late Templeto-

nian ⁄ Floran). Euagnostus opimus Zone, localities M412,

QML136, QML152.

Genus LOXONEPEA Opik, 1970

1970 Loxonepea; Opik, p. 21.

Type species. Loxonepea loxophrys Opik, 1970, p. 22.

Revised diagnosis. Cranidium trapeziform, length (sag.) 95

per cent post-palpebral cranidial width (tr.); glabella

moderately tapered, width (tr.) at anterior margin 50 per

cent occipital ring width, glabellar length (sag.) 50 per

cent cranidial length, S1–S2 directed posteriorly, S3 direc-

ted laterally; lateral occipital lobes separated from poster-

ior cranidial border by shallow furrow; preglabellar boss

clavate; eye ridge strongly arched anteriorly, directed

strongly anterolaterally from axial line.

Loxonepea loxophrys Opik, 1970

Text-figure 11A–C

v*1970 Loxonepea loxophrys Opik, p. 22, pl. 17, fig. 1; p. 22,

text-fig. 7.

v1970 Loxonepea sp. nov. ND Opik, p. 23, pl. 17, fig. 2.

Holotype. CPC7327, cranidium from the Currant Bush Lime-

stone, locality M124 (Text-fig. 11A–B).

Other material. One cranidium: CPC7328.

EXPLANATION OF PLATE 6

Figs 1–9. Penarosa netenta Jell, 1977. 1, QMF7059, holotype, internal mould of cranidium; QML152; · 4Æ5. 2, QMF7061, internal

mould of partial exoskeleton; QML152; · 4. 3)4, QMF7065, internal mould of partial exoskeleton; QML136. 3, dorsal view,

stereo pair; · 3Æ5. 4, oblique lateral view; · 3. 5–6, QMF7062, internal mould of partial exoskeleton; QML152. 5, dorsal view;

· 5. 6, enlargement of pygidium; · 8Æ5. 7, QMF7372, internal mould of partial cranidium; QML136; · 3. 8, QMF7060,

internal mould of librigena; QML136; · 4. 9, QMF7067, latex cast of external mould of librigena; QML136; · 3Æ5.

506 P A L A E O N T O L O G Y , V O L U M E 4 8

Diagnosis. As for genus.

Description. Cranidium trapeziform, length (sag.) approximately

95 per cent post-palpebral cranidial width (J5); strongly convex

(sag. and tr.). Anterior and posterior margins obscured. Facial

sutures obscured. Glabella moderately tapered, width (tr.) at

anterior margin (K5) 50 per cent occipital lobe width (K); mod-

erately (sag.) and strongly (tr.) convex; frontal lobe bluntly

1 2

3

4

5 6

7

8 9

PLATE 6

PATERSON, Penarosa

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 507

rounded; glabellar length (B1) (sag.) averages 55 per cent crani-

dial length. Axial furrow mostly shallow and wide (sag. and ex-

sag.); preglabellar furrow moderately shallow across entire width

with pit developed at midpoint. Lateral glabellar furrows deep,

S1 strongly directed posteriorly at approximately 45 degrees to

axial furrow, S2 parallel to and shorter (tr.) than S1, S3 directed

laterally and shorter (tr.) than S2. Occipital ring slightly elevated

above remainder of glabella, strongly convex (tr.); anterior and

posterior margins medially convex; lateral parts of occipital lobe

directed slightly anteriorly, separated from posterior cranidial

border by shallow furrow. S0 convex anteriorly medially and

slightly concave laterally, wide (sag.), shallow medially to deep

laterally. Preglabellar field with clavate boss strongly convex (sag.

and tr.), strongly downsloping posteriorly, length averages 80

per cent glabellar length (B1), anterior well rounded, widest (tr.)

anteriorly, maximum width (tr.) averages 80 per cent occipital

lobe width (K). Anterior border obscured. Fixigena convex, pre-

ocular area downsloping anteriorly. Palpebral lobe crescentic,

length (exsag.) approximately 50 per cent glabellar length (B1);

anterior end located opposite posterior half of preglabellar boss,

posterior end located opposite S2. Eye ridge of moderate relief,

strongly arched anteriorly, bifurcating; directed strongly antero-

laterally from glabella; proximal end connected to frontal lobe,

distal end separated from palpebral lobe by shallow palpebral

furrow. Palpebral area of fixigena strongly downsloping adaxially

from palpebral lobe; postocular area of fixigena downsloping

posteriorly. Baccula weakly to moderately developed. Posterolat-

eral projection of fixigena downsloping. Posterior border convex

(exsag.), expanding abaxially; border furrow deep, wide (exsag.),

slightly expanding abaxially.

Rostral plate, hypostome, thorax, and pygidium unknown.

Cranidial surface covered with interspersed small and med-

ium-sized granules; frontal area, including preglabellar boss, cov-

ered in genal caeca.

Remarks. Opik (1970) differentiated Loxonepea sp. nov.

ND from L. loxophrys by its wider frontal area, more bul-

bous anterior and lower posterior portions of the pregla-

bellar boss, wider angle of divergence of the eye ridges,

and lower palpebral lobes. The frontal area is not com-

pletely preserved in Loxonepea sp. nov. ND (CPC7328) or

the holotype of L. loxophrys, and only the anterior end of

the right palpebral lobe is preserved in the holotype of

L. loxophrys; hence, these specimens are unreliable for

comparison of these characters. In Opik’s (1970, p. 23)

description of the preglabellar boss of L. loxophrys, he

A

B C

TEXT -F IG . 11 . Loxonepea loxophrys Opik, 1970. A–B, CPC7327, holotype, silicified cranidium; M124. A, dorsal view, stereo pair;

· 7. B, oblique lateral view; · 7Æ5. C, CPC7328, latex cast of external mould of cranidium; M122; · 5Æ5.

508 P A L A E O N T O L O G Y , V O L U M E 4 8

noted that the boss ‘gains in tumidity forward’; however,

the same condition is observed in Loxonepea sp. nov. ND,

and therefore the differentiation of the two species using

this character is not possible. With regard to the angle of

divergence of the eye ridges, measurements reveal that the

angle for L. loxophrys is 80 degrees, whereas the angle for

Loxonepea sp. nov. ND is 110 degrees. The difference of

30 degrees is most likely due to the difference in size of

these specimens. The specimen of Loxonepea sp. nov. ND

is larger than the holotype of L. loxophrys: the glabellar

lengths are 4Æ5 mm and 2Æ8 mm, respectively. Therefore,

it is probable that the difference in the angle of diver-

gence in the eye ridges relates to the rearward migration

of the palpebral lobes during growth.

Stratigraphical occurrence. Middle Cambrian (Late Templeto-

nian ⁄ Floran). Acidusus atavus Zone, Age Creek Formation, local-

ity M122. Euagnostus opimus Zone, Currant Bush Limestone,

locality M124.

Genus FERENEPEA Opik, 1967

1967 Ferenepea Opik, p. 362.

1967 Ascionepea Opik, p. 365.

Type species. Ferenepea hispida Opik, 1967, p. 362.

Revised diagnosis. Cranidium trapeziform, length (sag.) 75

per cent post-palpebral cranidial width (tr.); glabella gently

tapered, width (tr.) at anterior margin 70 per cent occipital

lobe width, glabellar length (sag.) 70 per cent cranidial

length, S1 and S2 directed posteriorly, S3 poorly developed;

lateral occipital lobes connected to posterior cranidial bor-

der; preglabellar boss subquadrate; eye ridge slightly arched

anteriorly, directed slightly posteriorly abaxially.

Remarks. Opik (1967) distinguished Ascionepea from Fer-

enepea only by its flat and downsloping or obsolete anter-

ior border. Specimens of Ascionepea illustrated by Opik

(1967, pl. 40, figs 3–7; pl. 46, fig. 4) certainly show this

condition; however, these specimens also represent the

smallest of the Mindyallan species erected by Opik. Using

the glabellar length as a standard measure, type specimens

of Ascionepea range from 0Æ9 to 1Æ6 mm, with the holotype

of Ascionepea janitrix representing the largest specimen,

whereas type specimens of Ferenepea range from 1Æ9 to

2Æ1 mm. The most parsimonious view is that the four

Mindyallan species represent an ontogenetic series belong-

ing to a single species. The cranidia of Ascionepea anitys,

which lack an anterior border, represent the early holaspid

growth stages, A. janitrix represents an intermediate stage

in which the border has developed into a flat, downslop-

ing anterior border, while the cranidia of Ferenepea hispida

and F. pilaris represent the end members of the series and

have a well-developed anterior border. It is for this reason

that Ferenepea, and its type species F. hispida, were chosen

as the valid genus and species.

Ferenepea hispida Opik, 1967

Plate 7, figures 1–15

v*1967 Ferenepea hispida Opik, p. 362, pl. 39, figs 7a)8;

pl. 40, fig. 1a–b.

v1967 Ferenepea pilaris Opik, p. 364, pl. 40, fig. 2.

v1967 Ascionepea janitrix Opik, p. 365, pl. 40, fig. 3.

v1967 Ascionepea anitys Opik, p. 366, pl. 40, figs 4–6; pl. 46,

fig. 4.

v1967 Ascionepea sp. aff. anitys Opik, p. 366, pl. 40, fig. 7.

Holotype. CPC5666, cranidium from the O’Hara Shale, locality

D29 (Pl. 7, figs 1–4).

Other material. Eight cranidia: CPC5667, 5669–5674, 37064; one

librigena: CPC5668.

Diagnosis. As for genus.

Description. Cranidium trapeziform, length (sag.) 75 per cent

post-palpebral cranidial width (J5); convex (sag. and tr.); anter-

ior margin gently and evenly curved; posterior margin transverse

to distally strongly posterolaterally directed. Anterior branches of

facial sutures subparallel to about level with midlength of frontal

area (exsag.), then convergent to anterior margin; posterior

branches strongly divergent, curved to distal end of posterolater-

al projection. Glabella gently tapered, width (tr.) at anterior

margin (K5) averages 70 per cent occipital lobe width (K); mod-

erately (sag.), and strongly (tr.) convex; frontal lobe rounded,

projecting anteriorly beyond eye ridges; glabellar length (B1)

(sag.) averages 70 per cent cranidial length. Axial furrow of

moderate depth, and wide (tr.); preglabellar furrow moderately

deep across entire width, and wide (sag. and exsag.). Lateral gla-

bellar furrows deep, S1 directed posteriorly at approximately 45

degrees to axial furrow, S2 directed posteriorly and shorter (tr.)

than S1, S3 poorly developed to absent. Occipital ring not eleva-

ted above glabella, strongly convex (tr.), length (sag.) averages

25 per cent glabellar length; posterior margin convex posteriorly;

lateral parts of the occipital lobe directed slightly anteriorly, con-

nected to posterior cranidial border. S0 curved anteriorly, wide

(sag.), shallow medially to deep laterally. Frontal area length

(sag.) averages 35 per cent cranidial length. Preglabellar field

convex; boss subquadrate, convex (sag. and tr.), occupying entire

length of preglabellar field, length averages 25 per cent cranidial

length. Anterior border convex (sag. and exsag.), flattened dor-

sally, narrowing laterally. Anterior border furrow deep, wide

(sag. and exsag.). Fixigena convex, preocular area slightly down-

sloping anteriorly. Palpebral lobe small, length (exsag.) approxi-

mately 20 per cent glabellar length (B1). Eye ridge of moderate

relief, slightly arched anteriorly, bifurcates near axial furrow,

directed slightly posteriorly abaxially; proximal end separated

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 509

from frontal lobe by axial furrow, distal end abuts palpebral fur-

row. Palpebral and postocular areas of fixigena gently downslop-

ing adaxially. Baccula poorly developed. Posterolateral projection

of fixigena strongly downsloping, becoming narrower abaxially.

Posterior border widens slightly from axial furrow, then widens

more rapidly as it curves posteriorly, reaching its maximum

width (exsag.) at the posterior extremity of the fixigena. Poster-

ior border furrow widens slightly and evenly as it extends from

the axial furrow, at the same time curving slightly posteriorly;

near its distal extremity it abruptly curves forward, widens and

becomes less clearly defined.

Librigenae represented by one continuous unit, without a

median connective suture; lateral margin curved; inner (sutural)

margin between librigenal field and genal spine with embayment

to accommodate the posterolateral projection of the fixigena.

Border convex and continuous around entire unit, becoming

narrower at base of genal spine. Genal spine with a narrow base,

occupying approximately 50 per cent of the total librigenal

length.

Rostral plate, hypostome, thorax and pygidium unknown.

Exoskeletal surface covered in coarse granules, interspaced

with small, densely spaced granules. The frontal area and post-

erolateral projections of the fixigena of the cranidium are cov-

ered in genal caeca.

Remarks. Opik (1967, p. 364) differentiated Ferenepea pi-

laris from F. hispida by its ‘relatively large palpebral lobes,

overall pustulose boss, interocular cheeks about 1.1 of gla-

bellar width, and the trapezoidal outline of the crani-

dium’. Examination of specimens of F. hispida shows that

the palpebral lobes are rather poorly preserved, and

appear to be broken in some specimens (Pl. 7, figs 1, 7).

Comparison of surface ornamentation between species is

difficult because the holotype of F. pilaris (CPC5669) is

silicified and beekite rings obscure much of the surface

ornament (Pl. 7, fig. 10). The outline of the cranidium in

both species of Ferenepea is very similar. Based on this

evidence, there are no grounds on which to separate spec-

imens of F. hispida and F. pilaris. All of the characters

Opik (1967) used to differentiate Ascionepea anitys from

A. janitrix can be attributed to ontogenetic variation.

Such characters include the absence of an anterior border

furrow, minute palpebral lobes and the relative width of

the interocular cheeks. In specimens of A. anitys, which

are considerably smaller than the holotype of A. janitrix,

the anterior border has not yet developed, and hence the

absence of a border furrow (Pl. 7, figs 13–15). Moreover,

morphological characters such as palpebral lobes and the

relative width of interocular cheeks commonly display all-

ometry during growth, thus explaining why small speci-

mens of A. anitys possess smaller palpebral lobes and

wider interocular cheeks than those of A. janitrix.

The librigenal unit (CPC5668) is believed to have been

correctly assigned to Ferenepea hispida by Opik (1967)

because: (1) it is similar in size to associated cranidia; the

width (tr.) of the librigenal unit is 3Æ6 mm and the aver-

age width of the cranidium of F. hispida is around

4Æ5 mm; (2) the inner sutural margin exhibits an embay-

ment that conforms to the outline of the distal portion of

the posterolateral projection of the fixigenae; and (3) the

surface ornament of the librigenal unit is identical to that

of the cranidia of F. hispida.

Stratigraphical occurrence. Upper Middle–lower Upper Cambrian

(Boomerangian–Mindyallan). Lejopyge laevigata Zone, Steamboat

Sandstone, locality G103. Erediaspis eretes Zone, Mungerebar

Limestone, localities G8, G9, G114, G119, G417, G429. Acmarha-

chis quasivespa Zone, Mungerebar Limestone, localities G10,

G127, G150. Glyptagnostus stolidotus Zone, O’Hara Shale, localit-

ies D6, D28, D29; Georgina Limestone, locality W1.

Acknowledgements. I thank my supervisor Glenn A. Brock (Mac-

quarie University) for advice and support throughout the entire

period of this study, and for his assistance in the field. Ruth

Mawson and John A. Talent (Macquarie University) provided

much needed financial support for fieldwork. Thanks to John R.

Laurie (Geoscience Australia) for the loan of type material

housed in the Commonwealth Palaeontological Collection

(CPC), assistance with photography, commenting on an early

draft of the manuscript, and for encouraging me to work on the

nepeids. I am indebted to Nigel C. Hughes (University of Cali-

fornia, Riverside) for assistance with PCA. Thanks to Peter A.

Jell (Queensland Museum) for discussions, generous hospitality,

and permission to examine and photograph the type material of

N. narinosa and P. netenta during a visit to the Queensland

Museum in January 2003. I am grateful to Jim Jago (University

of South Australia) for providing images of a new species of Ne-

pea from Tasmania. Thanks also to Dave Mathieson for assist-

EXPLANATION OF PLATE 7

Figs 1–15. Ferenepea hispida Opik, 1967. 1)4, CPC5666, holotype, internal mould of cranidium; D29. 1, dorsal view, stereo pair; · 7.

2, oblique lateral view; · 7. 3, anterior view; · 8. 4, anterolateral view; · 5. 5–6, CPC5668, internal mould of librigenal unit; D29. 5,

lateral view; · 7Æ5. 6, anterior view; · 10. 7–9, CPC5667, internal mould of cranidium; D29. 7, dorsal view, stereo pair; · 7. 8, anterior

view; · 7. 9, anterolateral view; · 8Æ5. 10, CPC5669, silicified cranidium, holotype of Ferenepea pilaris Opik, 1967; G8; · 7. 11–12,

CPC5670, internal mould of cranidium, holotype of Ascionepea janitrix Opik, 1967; G103. 11, dorsal view; · 10. 12, anterolateral view;

· 7Æ5. 13, CPC5673, silicified cranidium, holotype of Ascionepea anitys Opik, 1967; G429; · 8. 14, CPC5671, silicified cranidium; G119;

· 9Æ5. 15, CPC5672, silicified cranidium; G8; · 16.

510 P A L A E O N T O L O G Y , V O L U M E 4 8

ance in the field, and Lloyd and Wendy Hick (owners of Thorn-

tonia Station) for access to the field area. Fred Sundberg and

Jim Jago provided helpful and informative reviews of the manu-

script. Partial funding for this research was provided by the

Betty Mayne Scientific Research Fund of the Linnean Society of

NSW.

PLATE 7

1

2

3 4

5

6

7

8

9

10 11 12

13 14 15

PATERSON, Ferenepea

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 511

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APPENDIX

1. Locality register

D6, Opik 1967; 21�25¢S 140�00¢E, ‘lower chert bed’ of the

O’Hara Shale, Selwyn Range, north-west Queensland; Glyptag-

nostus stolidotus Zone (Opik 1967).

D28, Opik 1967; 21�25¢S 139�58¢E, ‘lower chert bed’ of the

O’Hara Shale, Selwyn Range, north-west Queensland; Glyptag-

nostus stolidotus Zone (Opik 1967).

D29, Opik 1967; 21�26¢S 139�59Æ5¢E, ‘lower chert bed’ of the

O’Hara Shale, Selwyn Range, north-west Queensland; Glyptag-

nostus stolidotus Zone (Opik 1967).

D54, Opik 1970; 21�57¢S 139�04¢E, Steamboat Sandstone,

Quita Bore, on the bank of Quita Creek, Urandangi area, north-

west Queensland; Lejopyge laevigata Zone (Opik 1970, 1979).

D95, Opik 1970; 21�56¢S 139�00¢E, Steamboat Sandstone,

Quita Creek, Urandangi area, north-west Queensland; Lejopyge

laevigata Zone (Opik 1970).

D108, Opik 1970; 2Æ4 km south of locality D54, detrital lime-

stone layer at the base of the Steamboat Sandstone, Urandangi

area, north-west Queensland; Lejopyge laevigata Zone (Opik

1970).

G8, Opik 1967; 22�07¢S 139�12¢E, limestone horizon 7 m above

the base of the Mungerebar Limestone, Mungerebar-Mindyalla

area, north-west Queensland; Erediaspis eretes Zone (Opik 1967).

G9, Opik 1967; 22�08Æ5¢S 139�10¢E, light grey limestone of the

Mungerebar Limestone overlain by Cretaceous sandstone and

shale in east-facing escarpment, Mungerebar-Mindyalla area,

north-west Queensland; Erediaspis eretes Zone (Opik 1967).

G10, Opik 1967; 22�08¢S 139�15¢E, dark grey, banded lime-

stone of the Mungerebar Limestone, Mungerebar-Mindyalla area,

north-west Queensland; Acmarhachis quasivespa Zone (Opik

1967).

G103, Opik 1967; 22�08¢S 138�57¢E, chert biscuits weathered

out of shale from the top of the Steamboat Sandstone, Mungere-

bar-Mindyalla area, north-west Queensland; Lejopyge laevigata

Zone (Opik 1967).

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 513

G114, Opik 1967; 22�12¢S 138�57¢E, pale yellow limestone of

the Mungerebar Limestone, Mungerebar-Mindyalla area, north-

west Queensland; Erediaspis eretes Zone (Opik 1967).

G119, Opik 1967; 22�15¢S 139�00¢E, bituminous flaggy lime-

stone with chert and calcite pods of the Mungerebar Limestone,

Mungerebar-Mindyalla area, north-west Queensland; Erediaspis

eretes Zone (Opik 1967).

G127, Opik 1967; 22�17Æ5¢S 138�59Æ5¢E, bituminous and grey

sandy limestone of the Mungerebar Limestone, Mungerebar-

Mindyalla area, north-west Queensland; Acmarhachis quasivespa

Zone (Opik 1967).

G150, Opik 1967; 22�15Æ5¢S 138�57Æ5¢E, limestone with chert

and siliceous laminae of the Mungerebar Limestone, Mungere-

bar-Mindyalla area, north-west Queensland; Acmarhachis quasiv-

espa Zone (Opik 1967).

G417, Opik 1967; 22�09¢S 139�11¢E, flaggy bituminous lime-

stone of the Mungerebar Limestone, Mungerebar-Mindyalla area,

north-west Queensland; Erediaspis eretes Zone (Opik 1967).

G429, Opik 1967; 22�13¢S 139�01¢E, thin-bedded limestone,

chert and limestone breccia of the Mungerebar Limestone,

Mungerebar-Mindyalla area, north-west Queensland; Erediaspis

eretes Zone (Opik 1967).

GF1, new locality; 19�33¢8¢¢S 138�55¢16¢¢E, thin-bedded to

laminated grey limestone, 5 m above the base of the Gowers

Formation (type section), 5 km south-south-west of Thorntonia

homestead, north-west Queensland; Euagnostus opimus Zone

(Shergold and Southgate 1986).

H4, Opik 1970; coordinates unknown, black bituminous lime-

stone of the Arthur Creek Formation, 32 km due east from

Huckitta Station, close to the Arthur River, Northern Territory;

Acidusus atavus Zone (Opik 1970).

M28, Opik 1970 (see also Jell and Robison 1978); 19�27¢S138�38Æ5¢E, bituminous sandy limestone of the Currant Bush

Limestone, Camooweal area, north-west Queensland; Ptychagnos-

tus punctuosus Zone (Opik 1970).

M41, Opik 1970; 19�27Æ5¢S 138�37¢E, laminated grey sandy

limestone with chert pods of the V-Creek Limestone, Camoo-

weal area, north-west Queensland; Doryagnostus deltoides (¼punctuosus + nathorsti) Zone (Opik 1970, 1979; Laurie 1988).

M54, Opik 1970; 19�37Æ3¢S 138�38¢E, grey marly limestone of

the V-Creek Limestone, Douglas Creek stream bed, just south of

Undilla homestead, Camooweal area, north-west Queensland;

Ptychagnostus punctuosus Zone (Opik 1970, 1979; J. Laurie, pers.

comm. 2002).

M122, Opik 1970; 19�30Æ7¢S 138�47Æ6¢E, oolitic limestone and

chert interbed within the Age Creek Formation, Camooweal

area, north-west Queensland; Acidusus atavus Zone (Opik 1970).

M123, Opik 1970; 19�31¢S 138�47Æ6¢E, grey and pink lime-

stone and chert of the Currant Bush Limestone, collected from

the lowermost 3–5 m of a north-facing, low-angle cuesta (30 m

high), Camooweal area, north-west Queensland; Euagnostus opi-

mus Zone (Opik 1970, 1979; Laurie 1988).

M124, Opik 1970; 19�31Æ6¢S 138�47Æ4¢E, grey bituminous lime-

stone and chert of the Currant Bush Limestone, Camooweal

area, north-west Queensland; Euagnostus opimus Zone (Opik

1970, 1979).

M130, Opik 1970; 19�35Æ5¢S 138�48Æ5¢E, shale and chert at the

top of the Currant Bush Limestone, Camooweal area, north-west

Queensland; Ptychagnostus punctuosus Zone (Opik 1970, 1979; J.

Laurie, pers. comm. 2002).

M133, Opik 1970; 19�35¢S 138�41¢E, Split Rock Sandstone,

Camooweal area, north-west Queensland; Goniagnostus nathorsti

Zone (Opik 1970).

M141, Opik 1970; 19�39Æ5¢S 138�48¢E, red sandstone of the

Split Rock Sandstone, Camooweal area, north-west Queensland;

Goniagnostus nathorsti Zone (Opik 1970).

M157, Opik 1970; 19�25¢S 138�35¢E, bituminous limestone of

the Age Creek Formation, Morstone-Thorntonia area, north-

west Queensland; Euagnostus opimus Zone.

M160, Opik 1970; 19�23Æ5¢S 138�35Æ5¢E, chert interbed in

dolomite of the Age Creek Formation, Morstone-Thorntonia

area, north-west Queensland; Euagnostus opimus Zone (Opik

1970, 1979).

M179, Opik 1970; 18�38¢S 137�56Æ3¢E, grey nodular limestone

interbedded with shale layers in lower part of the Currant Bush

Limestone, southern bank of Lancewood Creek, Mount Drum-

mond area, Northern Territory; Acidusus atavus Zone (Opik

1970, 1979).

M180, Opik 1970; 18�38¢S 137�57Æ5¢E, grey marly limestone of

the Currant Bush Limestone, on Lancewood Creek, Mount

Drummond area, Northern Territory; Euagnostus opimus Zone

(Opik 1970, 1979; Laurie 1988).

M186, Opik 1970; 18�38Æ5¢S 137�58¢E, grey marly limestone of

the Currant Bush Limestone, approximately 0Æ8 km west of

locality M180 in the bed of Lancewood Creek, Mount Drum-

mond area, Northern Territory; Euagnostus opimus Zone (Opik

1970).

M226, Opik 1970; 20�09Æ5¢S 138�30¢E, sandstone and silicified

siltstone of the Split Rock Sandstone, west-facing scarp, Mount

Isa area, north-west Queensland; Goniagnostus nathorsti Zone

(Opik 1970).

M276, Opik 1970; 19�59Æ2¢S 138�30Æ4¢E, red sandstone in the

lower parts of the Split Rock Sandstone, overlying the thick-bed-

ded Mail Change Limestone exposed in a quarry along the Bar-

kly Highway, Camooweal area, north-west Queensland;

Goniagnostus nathorsti Zone (Opik 1970, 1979).

M344, Opik 1970; 19�57Æ5¢S 138�31¢E, white friable quartzose

sandstone in the uppermost part of the Split Rock Sandstone,

located at the face of an intermittent waterfall at the head of

Waroona Creek, Camooweal area, north-west Queensland; Goni-

agnostus nathorsti Zone (Opik 1970).

M393, Opik 1970; 18�38¢S 138�15¢E, silty siliceous limestone

of the Currant Bush Limestone, Lawn Hill area, north-west

Queensland; Euagnostus opimus Zone (Opik 1970).

M412, Opik 1970; 19�31¢S 138�53¢E, siliceous shale and chert

of the Inca Formation (¼ Chummy Bore Formation, sensu de

Keyser and Cook 1972 ¼Gowers Formation, sensu Southgate

1986), Chummy Bore, 7Æ5 km west-south-west of Thorntonia

homestead, north-west Queensland; Euagnostus opimus Zone

(Opik 1970, 1979).

M417, Opik 1970; 19�57¢S 138�29Æ5¢E, Split Rock Sandstone

(type locality), also the type locality for Nepea narinosa (see

Whitehouse 1939), Split Rock Waterhole on Waroona Creek,

approximately 3 km north of the Barkly Highway, Camooweal

area, north-west Queensland; Goniagnostus nathorsti Zone (Opik

1970).

514 P A L A E O N T O L O G Y , V O L U M E 4 8

M421, Opik 1970; 19�48Æ5¢S 138�32¢E, Split Rock Sandstone,

Emu Soak on Emu Creek, Camooweal area, north-west Queens-

land; Goniagnostus nathorsti Zone (Opik 1970).

QML136, Jell 1977; 19�31¢S 138�52¢E, weathered red, white

and yellow siliceous shales of the Chummy Bore Formation,

sensu de Keyser and Cook (1972) (¼ Gowers Formation, sensu

Southgate 1986) at Chummy Bore, 7Æ5 km west-south-west of

Thorntonia homestead, north-west Queensland; Euagnostus opi-

mus Zone (Jell 1977).

QML152, Jell 1977; 19�31Æ5¢S 138�52¢E, weathered red, white

and yellow siliceous shales of the Chummy Bore Formation,

sensu de Keyser and Cook (1972) (¼ Gowers Formation, sensu

Southgate 1986), 1Æ7 km south of Chummy Bore, 6 km south-

west of Thorntonia homestead, north-west Queensland; Euagnos-

tus opimus Zone (Jell 1977).

UQL256, Jell and Robison 1978 (see also Whitehouse 1936,

1939); 19�26¢S 138�43¢E, Currant Bush Limestone, along the for-

mer Camooweal to Burketown Road, 31 km west-north-west of

Thorntonia homestead, north-west Queensland; Euagnostus opi-

mus Zone (Jell and Robison 1978).

UQL463, Jell and Robison 1978; Currant Bush Limestone, on

top of a hill 5Æ6 km south of Thorntonia homestead on the left

bank (facing downstream) of the West Thornton River, north-

west Queensland; Euagnostus opimus Zone (Jell and Robison

1978).

W1, Opik 1967; 23�00¢S 138�49¢E, bituminous limestone with

calcite pods of the Georgina Limestone, Glenormiston-Sylvester

Creek area, north-west Queensland; Glyptagnostus stolidotus

Zone (Opik 1967).

2. Cranidial measurements

Commonwealth Palaeontological Collection specimens CPC4740-4742, 7272–7335 are illustrated by Opik (1970), and specimens

CPC37064–37136 come from unillustrated collections sampled by A. A. Opik and collections I have made from locality GF1. Queens-

land Museum specimens QMF7059–7070 are illustrated by Jell (1977), and University of Queensland specimens UQF3335–3336 (now

housed at the Queensland Museum) are illustrated in Whitehouse (1939). All measurements in millimeters (mm). *, holotype speci-

men; NA, not applicable.

Specimen

no.

Locality Original

assignment

Assignment

herein

B1 F1 G1 J2 J5 K K5 PBL PBW

CPC4740 M417 Nepea narinosa Nepea narinosa 2Æ4 2Æ2 0Æ6 3Æ7 5Æ8 1Æ8 1Æ2 1Æ4 1Æ5CPC4741* M417 Nepea anoxys Nepea narinosa 4Æ5 3Æ8 0Æ7 6Æ7 10Æ4 3Æ6 2Æ3 3 3Æ9CPC7272 M417 Nepea narinosa Nepea narinosa 3Æ4 2Æ6 0Æ6 5Æ4 8Æ4 3 1Æ8 2 3Æ1CPC7273 M417 Nepea narinosa Nepea narinosa 3Æ7 2Æ8 0Æ4 4Æ8 9Æ8 3Æ2 1Æ8 2Æ4 3Æ6CPC7274 M421 Nepea narinosa Nepea narinosa 2Æ7 2 0Æ3 3Æ3 6Æ2 2Æ1 1Æ2 1Æ6 1Æ9CPC7276 M226 Nepea narinosa Nepea narinosa 2Æ2 1Æ7 0Æ3 3Æ9 5Æ9 1Æ9 1 1Æ2 1Æ8CPC7278 M226 Nepea narinosa Nepea narinosa 2Æ4 1Æ8 0Æ3 3Æ7 5Æ2 1Æ9 1 1Æ3 2

CPC7280 Nepea narinosa Nepea narinosa 2Æ9 2 0Æ2 4Æ4 5Æ8 2 1Æ3 1Æ5 2Æ3CPC7281 M133 Nepea sp. cf. exserta Nepea narinosa 4 3 0Æ2 6Æ1 9 3Æ2 1Æ8 2Æ1 3Æ7CPC7282 M141 Nepea sp. NB Nepea narinosa 3Æ7 2Æ8 0Æ3 7Æ2 10Æ3 2Æ8 1Æ7 2Æ1 3Æ2CPC7283 M41 Nepea sp. NA Nepea narinosa 3Æ9 2Æ6 0Æ3 4Æ7 7Æ6 3Æ3 1Æ4 2Æ3 2Æ1CPC7284* M344 Nepea exserta Nepea narinosa 3Æ2 2Æ6 0Æ6 5 7Æ4 2Æ9 1Æ5 1Æ5 2Æ3CPC7285* M54 Nepea tonsillata Nepea tonsillata 2Æ9 1Æ9 0Æ3 4Æ1 5Æ8 2Æ2 1Æ3 1Æ4 2

CPC7286* D108 Nepea avara Nepea narinosa 3Æ9 3Æ1 0Æ2 6Æ4 8Æ2 2Æ9 1Æ9 2Æ8 3Æ8CPC7287 D108 Nepea avara Nepea narinosa 3Æ5 3 NA NA 7Æ2 2Æ7 1Æ6 2Æ5 3Æ5CPC7288 D95 Nepea avara Nepea narinosa 2Æ7 1Æ9 NA NA 5Æ6 2 1Æ6 1Æ7 2

CPC7289 D95 Nepea avara Nepea narinosa 4Æ5 3Æ7 NA NA 9Æ3 3Æ8 2Æ5 3Æ3 4Æ2CPC7290* M123 Folliceps nans Nepea nans 1Æ8 1Æ2 0Æ1 NA 2Æ8 0Æ9 0Æ6 0Æ9 1

CPC7291 M124 Folliceps nans Nepea nans NA 2Æ3 0Æ3 4Æ2 5Æ6 NA 1Æ2 1Æ9 2Æ1CPC7292 M123 Folliceps nans Nepea nans 3Æ8 NA NA NA 7Æ4 3 1Æ6 2Æ5 3Æ2CPC7293 Nepea sp. nov. NC gen. et sp. indet. 2Æ8 NA NA NA NA 2Æ3 1Æ6 2Æ7 2Æ5CPC7295 H4 Penarosa sp. nov. PD Penarosa retifera NA 2Æ8 1 5Æ4 7Æ2 NA NA NA NA

CPC7296 H4 Penarosa sp. nov. PE Penarosa retifera 1Æ8 1Æ8 0Æ5 2Æ6 4Æ4 1Æ6 1 NA NA

CPC7297* M180 Penarosa retifera Penarosa retifera 5Æ8 6Æ5 2Æ5 12Æ1 13 5Æ1 4 NA NA

CPC7298 M186 Penarosa retifera Penarosa retifera 3Æ4 3Æ8 1 7Æ4 7 2Æ7 2Æ2 NA NA

CPC7299 M180 Penarosa retifera Penarosa retifera 3Æ6 3Æ8 1Æ7 6Æ6 8Æ6 2Æ9 2Æ2 NA NA

CPC7302 M160 Penarosa retifera Penarosa retifera 5Æ4 NA NA NA 12Æ4 4Æ8 3Æ6 NA NA

CPC7303 M180 Penarosa sp. PA Penarosa retifera 2Æ3 2Æ2 0Æ6 3Æ4 4Æ2 1Æ9 1Æ2 NA NA

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 515

Appendix. Continued

Specimen

no.

Locality Original

assignment

Assignment

herein

B1 F1 G1 J2 J5 K K5 PBL PBW

CPC7306 M393 Penarosa zeabunda Penarosa elaticeps 3 NA NA NA 7Æ2 2Æ4 1Æ7 NA NA

CPC7307 M179 Penarosa zeabunda Penarosa elaticeps 2Æ6 2Æ7 0Æ5 3Æ8 5Æ2 1Æ9 1Æ3 NA NA

CPC7308 M179 Penarosa zeabunda Penarosa elaticeps 2Æ7 2Æ8 0Æ5 5Æ4 5Æ8 2Æ1 1Æ3 NA NA

CPC7309 M179 Penarosa zeabunda Penarosa elaticeps 2 2 0Æ5 3Æ4 4 1Æ3 0Æ9 NA NA

CPC7310* M179 Penarosa zeabunda Penarosa elaticeps 2Æ9 3Æ2 0Æ7 4Æ9 5Æ8 2Æ1 1Æ2 NA NA

CPC7311* M179 Penarosa elaticeps Penarosa elaticeps 3Æ9 3Æ9 0Æ9 7Æ7 9Æ2 3Æ3 2Æ3 NA NA

CPC7312 M130 Penarosa petalifera Penarosa retifera 2Æ2 2 0Æ5 3Æ4 5Æ1 1Æ9 1Æ2 NA NA

CPC7313* M179 Penarosa meniscops Penarosa rhinodelphis 3Æ5 3Æ2 1 4Æ9 7Æ8 3Æ2 1Æ8 NA NA

CPC7314* M179 Penarosa rhinodelphis Penarosa rhinodelphis 3Æ1 3 1Æ2 4Æ2 6Æ4 2Æ8 1Æ5 NA NA

CPC7315 M179 Penarosa rhinodelphis Penarosa rhinodelphis 2Æ1 2Æ1 1 3 4 1Æ8 1 NA NA

CPC7316* M124 Penarosa melota Penarosa retifera 3Æ2 3Æ1 0Æ5 4Æ8 6Æ5 2Æ7 1Æ8 NA NA

CPC7317 M412 Penarosa meniscops Penarosa netenta 1Æ7 1Æ8 0Æ5 2Æ8 3Æ3 1Æ5 0Æ9 NA NA

CPC7318* M124 Penarosa vittata Penarosa retifera 3Æ7 4Æ5 1Æ2 7Æ4 9Æ4 3Æ4 2Æ2 NA NA

CPC7319 M124 Penarosa vittata Penarosa retifera 5Æ5 6Æ3 1Æ9 10Æ6 13Æ8 4Æ1 3Æ4 NA NA

CPC7320 M123 Penarosa sp. PB Penarosa retifera 4Æ7 4Æ4 1Æ2 8Æ7 10Æ1 3Æ9 2Æ8 NA NA

CPC7322* M28 Penarosa petalifera Penarosa retifera 3Æ1 2Æ6 0Æ7 4Æ1 5Æ4 2Æ6 1Æ8 NA NA

CPC7324 M28 Penarosa petalifera Penarosa retifera 3 2Æ4 0Æ4 4Æ7 NA 2Æ6 1Æ8 NA NA

CPC7325 M157 Penarosa petalifera Penarosa retifera 3Æ6 3Æ1 1 5 NA 3 2Æ3 NA NA

CPC7326 M157 Penarosa petalifera Penarosa retifera 3Æ2 2Æ9 0Æ5 NA NA 2Æ3 1Æ7 NA NA

CPC7329 M412 Penarosa sp. nov. PC Penarosa netenta 4 3Æ4 1 7Æ4 7Æ2 3Æ1 2Æ2 NA NA

CPC7330 M412 Penarosa sp. nov. PC Penarosa netenta 0Æ9 0Æ4 0Æ1 0Æ7 1Æ3 0Æ5 0Æ3 NA NA

CPC7331 M179 Penarosa zeabunda Penarosa elaticeps 0Æ7 0Æ2 0Æ1 0Æ5 0Æ9 0Æ3 0Æ2 NA NA

CPC7332 M179 Penarosa zeabunda Penarosa elaticeps 0Æ7 0Æ1 NA NA 0Æ9 0Æ3 0Æ3 NA NA

CPC7335 M180 Penarosa retifera Penarosa retifera 0Æ5 0Æ1 NA NA 0Æ9 0Æ3 0Æ2 NA NA

CPC37065 D54 NA Nepea narinosa 4Æ9 NA NA NA NA 4Æ2 2Æ7 2Æ9 5Æ2CPC37066 D54 NA Nepea narinosa 5Æ1 4 NA NA NA 4Æ2 2Æ4 3Æ1 4Æ4CPC37067 D54 NA Nepea narinosa 3Æ8 3Æ4 NA NA NA 2Æ6 1Æ9 2Æ9 3Æ6CPC37068 D54 NA Nepea narinosa 2Æ8 1Æ7 NA NA 5Æ6 2Æ1 1Æ3 1Æ4 2Æ5CPC37069 D54 NA Nepea narinosa 2Æ2 1Æ5 NA NA NA 1Æ6 1 1Æ2 1Æ9CPC37070 D54 NA Nepea narinosa 1Æ8 1Æ3 NA NA NA 1Æ3 0Æ8 1Æ2 1Æ4CPC37071 D54 NA Nepea narinosa 2Æ8 2Æ9 NA NA NA 1Æ9 1Æ2 1Æ9 2Æ6CPC37072 D54 NA Nepea narinosa 2Æ7 1Æ9 NA NA 6 2Æ1 1Æ1 1Æ7 2Æ3CPC37073 D54 NA Nepea narinosa 3Æ2 2Æ7 NA NA NA 2Æ7 1Æ5 2Æ3 2Æ6CPC37074 D54 NA Nepea narinosa NA 1Æ4 NA NA NA NA NA 1Æ1 1Æ4CPC37075 D54 NA Nepea narinosa 2Æ7 2Æ1 NA NA NA 1Æ9 1Æ3 1Æ8 2

CPC37076 D54 NA Nepea narinosa 3 2Æ7 NA NA NA 2Æ4 1Æ2 2Æ3 3Æ1CPC37077 D95 NA Nepea narinosa 3Æ6 3Æ1 NA NA 8Æ2 2Æ7 1Æ7 2Æ5 3Æ4CPC37078 D95 NA Nepea narinosa 4 3Æ5 NA NA 9 3Æ1 1Æ7 3Æ1 4Æ6CPC37080 M179 NA Penarosa elaticeps 2Æ8 3Æ1 0Æ5 6Æ2 NA 2Æ4 1Æ4 NA NA

CPC37082 M179 NA Penarosa elaticeps 3Æ1 3Æ2 0Æ7 6 6Æ8 2Æ4 1Æ7 NA NA

CPC37083 M179 NA Penarosa rhinodelphis 2Æ7 2Æ5 0Æ8 2Æ1 5Æ4 2Æ4 1Æ2 NA NA

CPC37084 M179 NA Penarosa elaticeps 1Æ6 1Æ7 0Æ5 2Æ7 3 1Æ4 0Æ7 NA NA

CPC37085 M179 NA Penarosa rhinodelphis NA 1Æ4 0Æ6 1Æ4 NA NA NA NA NA

CPC37086 M179 NA Penarosa rhinodelphis 2Æ5 2Æ3 0Æ9 2Æ8 4Æ3 1Æ9 1Æ1 NA NA

CPC37087 M179 NA Penarosa rhinodelphis 2 1Æ8 0Æ7 1Æ7 3Æ4 1Æ5 0Æ8 NA NA

CPC37088 M179 NA Penarosa elaticeps 2 2Æ1 0Æ4 3Æ8 4Æ8 1Æ7 1 NA NA

CPC37090 M179 NA Penarosa elaticeps 1Æ8 1Æ9 0Æ3 3 3Æ6 1Æ2 0Æ8 NA NA

CPC37091 M180 NA Penarosa retifera 4Æ7 5 1Æ5 9Æ4 10Æ4 3Æ9 2Æ8 NA NA

CPC37092 M180 NA Penarosa retifera 2Æ2 2 0Æ6 3Æ4 4 1Æ7 1Æ1 NA NA

CPC37093 M180 NA Penarosa retifera 3Æ8 4 1Æ2 7Æ6 NA 3Æ1 1Æ9 NA NA

CPC37095 M186 NA Penarosa retifera 2Æ9 2Æ2 0Æ6 5 6 2Æ2 1Æ5 NA NA

CPC37096 M180 NA Penarosa retifera 2Æ8 2Æ6 1Æ1 5Æ2 6Æ4 2Æ6 1Æ6 NA NA

CPC37097 M180 NA Penarosa retifera 2Æ6 2Æ6 0Æ9 5Æ2 NA 2 1Æ2 NA NA

CPC37098 M180 NA Penarosa retifera 4Æ3 4Æ6 2 8Æ1 9Æ8 3Æ5 2Æ8 NA NA

516 P A L A E O N T O L O G Y , V O L U M E 4 8

Appendix. Continued

Specimen

no.

Locality Original

assignment

Assignment

herein

B1 F1 G1 J2 J5 K K5 PBL PBW

CPC37099 M180 NA Penarosa retifera 4Æ6 NA NA NA NA 4Æ1 2Æ8 NA NA

CPC37100 M180 NA Penarosa retifera 4Æ3 5Æ7 2 9Æ2 NA 3Æ6 2Æ5 NA NA

CPC37101 M180 NA Penarosa retifera 3 NA NA NA 7Æ2 2Æ8 1Æ8 NA NA

CPC37102 M180 NA Penarosa retifera 3Æ9 5Æ1 1Æ3 8Æ6 8Æ8 3Æ2 2Æ6 NA NA

CPC37104 M180 NA Penarosa retifera 4Æ1 5 1Æ5 9 9Æ8 3Æ6 2Æ5 NA NA

CPC37106 M344 NA Nepea narinosa 2Æ9 2Æ2 0Æ3 4Æ2 6Æ6 2Æ6 1Æ4 1Æ8 2Æ2CPC37107 M344 NA Nepea narinosa 3Æ1 2Æ1 0Æ3 3Æ9 6Æ5 2Æ5 1Æ4 1Æ7 1Æ9CPC37108 M344 NA Nepea narinosa 2Æ1 1Æ2 0Æ2 2Æ4 NA 1Æ2 0Æ9 0Æ9 1Æ2CPC37110 M226 NA Nepea narinosa 3Æ2 2Æ1 0Æ3 4Æ5 6 2Æ1 1Æ3 1Æ6 2Æ3CPC37111 M226 NA Nepea narinosa NA NA NA NA NA NA NA 1Æ8 2Æ5CPC37112 M412 NA Penarosa netenta 3 2Æ8 0Æ6 5Æ5 NA 2Æ3 1Æ7 NA NA

CPC37115 M417 NA Nepea narinosa 3Æ7 2Æ5 0Æ5 4Æ3 7Æ7 3 1Æ6 1Æ8 2Æ3CPC37116 GF1 NA Penarosa retifera 4Æ8 5Æ3 2Æ2 9Æ5 11 4 3 NA NA

CPC37117 GF1 NA Penarosa retifera NA 2Æ5 0Æ8 5Æ8 NA NA NA NA NA

CPC37118 GF1 NA Penarosa retifera 5Æ1 5Æ5 1Æ8 12 NA NA NA NA NA

CPC37120 GF1 NA Penarosa retifera 4Æ8 5Æ4 1Æ9 9Æ4 11 3Æ7 2Æ8 NA NA

CPC37121 GF1 NA Penarosa retifera NA 6Æ2 2Æ2 11Æ4 13Æ2 NA NA NA NA

CPC37122 GF1 NA Penarosa retifera 5Æ3 5Æ5 2Æ2 11Æ3 NA 4Æ7 3Æ6 NA NA

CPC37123 GF1 NA Penarosa retifera 5Æ2 6Æ1 2Æ4 10Æ2 13Æ8 5Æ4 3Æ6 NA NA

CPC37124 GF1 NA Penarosa retifera 5Æ1 5Æ5 1Æ7 10Æ1 12 4Æ1 2Æ9 NA NA

CPC37125 GF1 NA Penarosa retifera 5Æ5 NA NA NA 13Æ5 4Æ8 3Æ6 NA NA

CPC37126 GF1 NA Penarosa retifera 4Æ5 NA NA NA 5Æ1 3Æ5 2Æ5 NA NA

CPC37128 GF1 NA Penarosa retifera 3Æ1 3Æ5 1Æ1 6Æ3 7Æ4 2Æ8 2 NA NA

CPC37129 GF1 NA Penarosa retifera 2Æ1 NA NA NA NA 1Æ6 1Æ2 NA NA

CPC37132 GF1 NA Penarosa retifera 3 3Æ3 1Æ1 6Æ2 7Æ6 2Æ8 1Æ8 NA NA

CPC37133 GF1 NA Penarosa retifera 1Æ6 NA NA NA NA 1Æ2 0Æ8 NA NA

CPC37134 GF1 NA Penarosa retifera 4Æ9 5Æ1 2 9Æ8 11Æ4 4Æ3 3Æ1 NA NA

CPC37135 GF1 NA Penarosa retifera NA 6Æ3 2Æ5 11Æ5 13Æ8 NA NA NA NA

CPC37136 GF1 NA Penarosa retifera 4Æ2 NA NA NA 9Æ3 3Æ3 2Æ1 NA NA

QMF7059* QML152 Penarosa netenta Penarosa netenta 2Æ9 3Æ1 1 5Æ2 6Æ2 2Æ4 1Æ7 NA NA

QMF7061 QML152 Penarosa netenta Penarosa netenta 2Æ9 3Æ6 1 6 7Æ6 2Æ7 2 NA NA

QMF7065 QML136 Penarosa netenta Penarosa netenta 3Æ4 3Æ8 1Æ1 5Æ8 8Æ2 2Æ8 1Æ8 NA NA

QMF7066 QML136 Penarosa netenta Penarosa netenta 3Æ2 3Æ3 0Æ9 5Æ3 7Æ4 2Æ6 1Æ8 NA NA

UQF3335* M417 Nepea narinosa Nepea narinosa 3 2Æ5 0Æ5 5Æ1 7Æ3 2Æ6 1Æ6 1Æ8 2Æ5UQF3336 M417 Nepea narinosa Nepea narinosa 4Æ6 3Æ5 0Æ7 7Æ6 11Æ2 3Æ9 2Æ7 2Æ8 3Æ9

NOTE ADDED IN PROOF

Since this paper was accepted for publication, two new articles

documenting nepeids have appeared. Jago et al. (2004) have

described two new species of Nepea and an indeterminate species

of Penarosa from the upper Middle Cambrian (Lejopyge laevigata

Zone) of north-west Tasmania. Australia; Nepea delicata is

described from Native Track Tier, and N. hellyeri and Penarosa

sp. are described from St. Valentines Peak. Lieberman (2004)

has documented Penarosa trinodus (Palmer and Gatehouse,

1972) from the Middle Cambrian Nelson Limestone at Hannah

Ridge in the Neptune Range, Antarctica.

J A GO , J. B., B A O , J.-S. and B A I L LI E , P. W, 2004. Late Mid-

dle Cambrian trilobites from St Valentines Peak and Native

Track Tier, northwestern Tasmania. Alcheringa, 28, 21–52.

L I E BE R M A N , B. S. 2004. Revised biostratigraphy, systematics,

and paleobiogeography of the trilobites from the Middle Cam-

brian Nelson Limestone, Antarctica. University of Kansas,

Paleontological Contributions, New Series, 14, 1–23.

P A T E R S O N : S Y S T E M A T I C S O F C A M B R I A N N E P E I D T R I L O B I T E S 517