Scalaspira (Gastropoda) from the Paleogene of the Transcaspian Region

15

ISSN 0031-0301, Paleontological Journal, 2007, Vol. 41, No. 1, pp. 15–27. © Pleiades Publishing, Ltd., 2007.Original Russian Text © O.V. Amitrov, E.A. Zhegallo, 2007, published in Paleontologicheskii Zhurnal, 2007, No. 1, pp. 15–26.

INTRODUCTION

The gastropods studied represent a group widelydistributed in the Paleogene (especially in the Oli-gocene) of western Europe (mainly the North SeaBasin). It is also present in the south of the formerUSSR, including the Transcaspian Region, where ninedifferent varieties (at least eight species) are recognizedfrom the Upper Eocene to the Oligocene–Mioceneboundary beds.

In the papers of the 19th–early 20th century, andeven in later publications,

Scalaspira

species were usu-ally described under generic name

Fusus

. Wenz (1938–1944) believed that the valid name for this genus was

Fusinus

Rafinesque, 1810 (=

Fusus

Bruguière, 1789,non Halbling, 1779). Kautsky (1925) assigned a groupof species from the Oligocene and Miocene of Europeto the genus

Aquilofusus

. Tembrock (1964, 1965, 1968)proposed a detailed revision of all these gastropods.She concluded that the genus

Aquilofusus

should beunited with several other gastropod genera including

Scalaspira

Conrad, 1862 and

Mohnia

Friele, 1879. Pre-viously, these genera were assigned to different fami-lies. According to Wenz, the genus

Aquilofusus

belongsto Fasciolariidae, subfamily Fusinidae, while

Sca-laspira

belongs to Muricidae (at that time only the typespecies of this genus was recorded from the Miocene ofNorth America), whereas

Mohnia

belonged to Buc-cinidae (it was thought that this genus was representedby several extant species from northern seas). Tem-brock suggested that the oldest available name

Sca-laspira

should be used for this united genus andassigned this genus to Buccinidae based on its proto-conch and on the structure of the radula of extant spe-cies previously assigned to

Mohnia

. Most workers(including this study) accepted the view of Tembrock,

although the spindle-shaped shell with a long siphonalcanal makes the species from the Cenozoic of Eurasiaconsiderably more similar to the typical

Fusus

than to

Buccinum

. It should be said that in one of the latestpapers on these gastropods (Gürs and Schnetler, 2004)the genus

Aquilofusus

is not synonymized with

Sca-laspira

(

Mohnia

is not mentioned), but assigned toBuccinidae.

Several issues arose while studying the Transcas-pian

Scalaspira

. Firstly, a wide range of opinions onspecies identifications has been published in westernEuropean works, which were also extensively used byRussian workers. Differences in identification were sig-nificantly reduced by the 1960s after Tembrock’s revi-sion, but no complete consensus has been achieved upto now. Secondly, the precision and quality of identifi-cations of the Transcaspian material are reducedbecause of its state of preservation. In some species noprotoconchs are known and fine details of ornamenta-tion are not preserved (especially in early whorls), i.e.,characters which Tembrock and some other workersconsider of having high taxonomic value. Thirdly, up tothe end of the 1950s the stratigraphic distribution of ourspecies was difficult to estimate because of uncertain-ties in the geology of the Transcaspian Region. Amitrov(2005) published a paper on the Eocene–Oligocenegastropod assemblages of western Kazakhstan, inwhich he also discussed the stratigraphy of these beds.Having mentioned the above paper, we still want to reit-erate several of the most important issues (see alsoTable 1). Up to the end of the 1950s it was not acknowl-edged that in the northern Ustyurt Plateau and the AralSea Region, the Chegan Formation (a long knownseries with a rich fauna presently dated as UpperEocene and possibly upper part of the Middle Eocene)is overlain by at least two series with normal marine

Scalaspira

(Gastropoda) from the Paleogene of the Transcaspian Region

O. V. Amitrov and E. A. Zhegallo

Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997 Russiae-mail: [email protected]; [email protected]

Received November 28, 2005

Abstract

—The composition and distribution of the species of the genus

Scalaspira

Conrad, 1862 in theEocene–Oligocene of western Kazakhstan are revised. Following Tembrock we assign this genus to Buccinidaeand synonymize

Aquilofusus

Kautsky, 1925 with it. The stratigraphic interval studied contains at least eight spe-cies. Three species are new:

S. alexeevi

(Middle? and Upper Eocene, Chegan Formation),

S. korobkovi

, and

S. kumsuatensis

(Upper Oligocene, Karatomak Beds).

DOI:

10.1134/S0031030107010029

Key words

:

Scalaspira

, Buccinidae, Upper Eocene, Oligocene, western Kazakhstan, Mangyshlak, Ustyurt.

PALEONTOLOGICAL JOURNAL

Vol. 41

No. 1

2007

SCALASPIRA

(GASTROPODA) FROM THE PALEOGENE OF THE TRANSCASPIAN REGION 17

Tab

le 2

.

Nam

es o

f th

e T

rans

casp

ian

Scal

aspi

ra

in th

e lit

erat

ure

Nam

e in

th

is p

aper

S

.

alex

eevi

sp. n

ov.

S

.

sube

rrat

ica

(Baj

arun

as, 1

912)

S

.

gros

sive

ntro

sa

(A

mitr

ov, 1

966)

(=

?

S

.

sube

rrat

ica

)

S

.

kend

erle

nsis

(A

mitr

ov, 1

966)

S

.

subg

rega

ria

(I

lyin

a, 1

955)

S

.

mul

tisu

lcat

a

(N

yst,

1845

)

S

. sp.

1

S

.

koro

bkov

i

S

.

kum

suat

ensi

s

Baj

arun

as

, 19

12

Fus

us

sube

rrat

i-cu

s

sp.

nov

.

Ilyi

na

,19

53

Fus

us

ustj

urte

nsis

A

lexe

iev,

in c

oll.

Ove

chki

n

, 19

54

Fus

us

sp.

nov

.?

Ilyi

na

,19

55

Fus

us

subg

rega

-ri

us

Ale

xeie

v, in

co

ll.

Fus

us

ustj

urte

nsis

A

lexe

iev,

in c

oll.

Ilyi

na

,19

60

Fus

us

sube

rrat

i-cu

s

Baj

arun

as

[par

t.]

Fus

us

sube

rrat

i-cu

s

Baj

arun

as

[par

t.]

Ale

xeev

, 19

63

Fus

us

sp.

nov

.

Fus

us

ustj

urte

nsis

sp

. nov

.

Fus

us

subg

rega

-ri

us

sp.

nov

.

Kor

obko

v

, 19

65

Aqu

ilof

usus

sub-

greg

ariu

s

(A

lex-

eev,

non

Ily

ina)

Aqu

ilof

usus

sub-

erra

ticu

s

(B

ajar

u-na

s) [

part

.?]

[?]

Aqu

ilof

usus

su

berr

atic

us (

Ba-

jaru

nas)

[pa

rt.?

]

Aqu

ilof

usus

mar

-ch

icus

(T

em-

broc

k, 1

864)

Aqu

ilof

usus

ust

-ju

rten

sis

(Ily

ina,

no

n A

lexe

ev)

Aqu

ilof

usus

aff

. pe

rege

r (B

eyri

ch,

1856

)

Aqu

ilof

usus

ele

-ga

ntul

us tr

icar

i-na

tus

(Koc

h et

W

iech

man

n,

1872

)

Aqu

ilof

usus

de-

shay

esi (

Nys

t, 18

45)

Am

itrov

, 19

66A

quilo

fusu

s su

ber-

ratic

us s

uber

rati-

cus

(Baj

arun

as)

Aqu

ilof

usus

gro

s-si

vent

rosu

s sp

. no

v.

Aqu

ilof

usus

sub

-er

rati

cus

kend

er-

lens

is s

ubsp

. nov

.

Kor

obko

v,

1967

Fus

us s

p. a

Fus

us m

ulti

sulc

a-tu

s (N

yst,

1845

) [p

art.]

Fus

us m

ulti

sulc

a-tu

s (N

yst,

1845

) [p

art.]

Tem

broc

k,

1968

S. (

Scal

aspi

ra)

sube

rrat

ica

(Ba-

jaru

nas,

191

2)

S. (S

cala

spir

a)er

ratic

a (K

onin

ck,

1837

) sub

sp.?

gr

ossi

vent

rosa

(A

mitr

ov,1

966)

S. (

Scal

aspi

ra)

kend

erle

nsis

(A

mitr

ov, 1

966)

S. (

Vag

anto

spi-

ra)

vill

ana

(Phi

l-ip

pi, 1

847)

S. (V

agan

tosp

ira)

m

ultis

ulca

ta

(Nys

t, 18

45)

Isae

va,

1970

Fus

us s

uber

rati

-cu

s B

ajar

unas

[p

art.]

Fus

us s

uber

rati

-cu

s B

ajar

unas

[p

art.]

Fus

us s

ubgr

egar

-iu

s A

lexe

iev

Am

itrov

, 19

71A

quil

ofus

us s

ub-

erra

ticu

s su

ber-

rati

cus

(Baj

aru-

nas,

191

2)

Aqu

ilof

usus

sub

-er

rati

cus

kend

er-

lens

is A

mitr

ov,

1966

Aqu

ilof

usus

sub

-gr

egar

ius

(Ily

ina,

19

55)

Aqu

ilof

usus

ust

-ju

rten

sis

(Ily

ina,

19

53)

18

PALEONTOLOGICAL JOURNAL Vol. 41 No. 1 2007

AMITROV, ZHEGALLO

overlying beds, including those with a specific Kenderlifaunal assemblage, are of Rupelian age, being equiva-lents of the Astsheairyk Formation, and that the marineRupelian beds in Mangyshlak (like in the northernUstyurt) are overlain by the Solionovskii Horizon, andabove that by the marine Karagie Formation (Chattian,equivalent of the Karatomak Beds). The Karagie For-mation contains the faunal locality near the KolmyshRavine that was previously thought to belong to theUzunbas Formation. Finally, the fourth issue compli-cating the situation (referred to by Amitrov, 2005, seealso Table 2) is that the large monograph on Cheganmollusks written by A.K. Alexeev before World War IIwas only published in 1963. Some authors, using Alex-eev’s manuscript redescribed species established byAlexeev, but provided their own descriptions and fig-ured their own material. This also applies to Scalaspiraspecies described as Fusus ustjurtensis Alexeiev (Ily-ina, 1953) and F. subgregarius Alexeiev (Ilyina, 1955).In addition, at least one species was misidentified byA.P. Ilyina. The species Fusus ustjurtensis identified byIlyina is found in the Chattian (Karatomak) Beds,whereas Alexeev’s species is Rupelian (described fromtwo shells from the Astsheairyk Formation); this is asynonym of F. suberraticus Bajarunas, 1912. Such sit-uations emphasize the importance of the Code of Zoo-logical Nomenclature. In this case the authorship ofthese species should be attributed to Ilyina, irrespectiveof whether her understanding of the species is same asAlexeev’s. Another problem is whether the Transcas-pian species are synonyms or subspecies of well-knownEuropean species. It is clear from Table 2 that we fol-low Tembrock and synonymize Scalaspira ustjurtensiswith S. multisulcata (Nyst, 1845). This point is dis-cussed below.

MORPHOLOGICAL CHARACTERS OF SCALASPIRA AND THEIR TAXONOMIC

APPLICATION

Tembrock attached particular importance to themorphology of the apical part of the shell. Based on thisshe recognized the subgenus Vagantospira Tembrock,1968, with the type species S. multisulcata (to this sub-genus she also assigned S. villana and S. houchei, whileother species she assigned to the nominal subgenus). InScalaspira s. s. smooth whorls of the protoconch growin almost the same plane, and the apex appears blunt,whereas in Vagantospira, the protoconch is conical.Another difference is that in some species of the nomi-nal subgenus, axial ridges appear at the end of theembryonic part of the shell, along with the first spiralribs, to form together a reticulate pattern. InVagantospira this is not observed. Tembrock warnedthat species very similar in ornamentation of the lastwhorls may in fact belong to different subgenera. In theTranscaspian material, the early whorls are rarely pre-served, but it is clear that S. suberratica and similar spe-cies belong to the nominal subgenus, whereas S. sub-

gregaria and S. “ustjurtensis” certainly belong toVagantospira. The value of these differences is anothermatter. Tembrock herself noted that there are speciesthat appear intermediate between the two subgenera.We believe that the “axial ridges” are only morestrongly developed regular growth lines, which can alsobe observed in Vagantospira.

The species differ (even if slightly) in the size oftheir shells. Table 3 shows that among the Transcaspiantaxa four species from the S. suberratica group have amaximum shell height of 74–83 mm; S. subgregaria,and S. multisulcata, about 50 mm; and the other spe-cies, no more than 42 mm. However, it should be saidthat large specimens of each species are rarely foundand may be broken; therefore, there is a possibility thatfuture collecting will result in the discovery of largershells (this especially concerns species represented byfew specimens). It should also be remembered that themaximum (and average) sizes of shells of the same spe-cies may be different in specimens from different beds.For instance, the Uzunbas fauna is different from theKulandy and Astsheairyk faunas in the smaller size ofthe specimens, which is also true for Scalaspira(Amitrov, 1966, 1971).

The general shape of the shell is described by quan-titative characters such as the apical angle (if the apexis broken, the angle of the earliest preserved whorl hasto be measured), the growth angle of the last whorl, andthe width-to-height (W/H) ratios of the shell, aperture,a whorl, etc. Differences in these characters betweenspecies are not great, but for every two pairs of speciesthey can be very distinct and can be used for identifica-tion. In gastropods, the shell does not usually growcompletely isometrically. The spire is usually conicalwith a slightly convex generating line, the growth angleof the last whorl is smaller than the apical angle, and theW/H ratio in large shells is smaller than in small shells.This also applies to Scalaspira, but in our species,allometry is not very distinct. It is best observed inS. subgregaria and S. grossiventrosa, whereas in S.alexeevi the difference between the growth angles ofearly and late whorls is on average only one degree, thegenerating line may be considered straight, evenslightly concave in some specimens.

Species are also distinguished by the degree of con-vexity or angularity of whorls and the position of themaximum convexity or curvature.

Presence or absence of axial ornamentation is animportant character. However, as noted by Tembrock,there are Scalaspira species in which some specimenspossess axial ribs, whereas others do not. Sometimes itis difficult to distinguish elements of axial ornamenta-tion from growth lines. However, Transcaspian speciesdo not impose such difficulties. Seven of them do nothave axial ornamentation (if ridges in the earliestwhorls are not counted), whereas two species haveclear axial ribs.

Morphology of spiral ornamentation is very impor-tant for identification. Usually, the ornamentation of theearly whorls is the least changeable and therefore most


SCALASPIRA (GASTROPODA) FROM THE PALEOGENE OF THE TRANSCASPIAN REGION 19

Tab

le 3

. M

orph

olog

ical

cha

ract

ers

of th

e Sc

alas

pira

spe

cies

und

er c

onsi

dera

tion

Spec

ies

Cha

ract

erS.

ale

xeev

iS.

sub

erra

-ti

caS.

gro

ssi-

vent

rosa

S. k

ende

r-le

nsis

S. s

ubgr

e-ga

ria

S. m

ulti

sul-

cata

S. s

p. 1

S. k

orob

kovi

S. k

umsu

a-te

nsis

Max

imum

hei

ght o

f th

e sh

ell,

mm

no le

ssth

an 8

3m

ore

than

74

8477

50m

ore

than

52

abou

t 42

abou

t 35

41

Wid

th/h

eigh

t rat

io o

f th

e sh

ell,

%33

–47

38–4

543

–50

36–4

737

–53

33–4

352

40–4

937

–43

Api

cal a

ngle

or

the

grow

th a

ngle

of

earl

y w

horl

s in

deg

rees

30–5

136

–47

50–6

038

–50

50–7

136

–50

mor

eth

an 5

440

–47

42–4

7

Gro

wth

ang

le o

f th

e la

st w

horl

in d

egre

es30

–54

30–4

540

–53

30–4

830

–57

27–4

343

34–4

529

–52

Ave

rage

dif

fere

nce

betw

een

angl

es in

de-

gree

s1.

14.

59.

12.

518

.17.

711

2.9

7.2

Shap

e of

the

gene

ratin

g lin

e of

the

coni

cal

spir

est

raig

htal

mos

t st

raig

htno

ticea

bly

conv

exal

mos

t st

raig

htst

rong

lyco

nvex

slig

htly

conv

exal

mos

t st

raig

htal

mos

t st

raig

htsl

ight

lyco

nvex

Who

rl h

eigh

t/wid

th r

atio

, %47

–64

47–6

242

–59

49–6

337

–57

45–6

452

–55

50–6

949

–66

Deg

ree

of w

horl

con

vexi

tysl

ight

fair

ly s

tron

gst

rong

stro

ngsl

ight

slig

htst

rong

fair

ly s

tron

gsl

ight

Uni

form

con

vexi

ty o

r sh

ould

ersh

ould

er is

de

velo

ped

only

in e

arly

w

horl

s

shou

lder

not

la

ter

than

in

inte

rmed

iate

w

horl

s

shou

lder

not

la

ter

than

in

inte

rmed

iate

w

horl

s

shou

lder

not

la

ter

than

in

inte

rmed

iate

w

horl

s

unif

orm

unif

orm

unif

orm

shou

lder

in e

arly

w

horl

s

shou

lder

in e

arly

w

horl

s

Num

ber

of a

xial

rib

s pe

r w

horl

––

––

––

–12

–19

8–16

Num

ber

of s

pira

l rib

s in

the

firs

t pos

tem

-br

yoni

c w

horl

4 ?

5?

?4–

65

?3?

?

Num

ber

of s

pira

l rib

s in

inte

rmed

iate

w

horl

s4–

8(u

sual

ly5–

7)

5–7

(usu

ally

5)

5–7

(usu

ally

5–6)

5–9

(usu

ally

5–6)

8–14

(usu

ally

11–1

2)

6–10

(usu

ally

7–9)

103–

85–

7(×

2)

Num

ber

of s

pira

l rib

s in

the

penu

ltim

ate

who

rl a

nd in

the

last

who

rl a

bove

the

con-

tinua

tion

of th

e su

ture

4–10

(usu

ally

5–7)

5–7

(usu

ally

5–6)

6–10

(usu

ally

6–8)

5–11

(usu

ally

7–9)

10–1

5(u

sual

ly11

–14)

7–10

(usu

ally

8–9)

10–1

44–

106–

7(×

2; ×

4)

Num

ber

of s

hells

stud

ied

in P

IN c

olle

ctio

ns21

053

1910

714

510

10–

129

in m

useu

ms

of S

t. Pe

ters

burg

(o

rigi

nals

)1

3–

–13

111

11

20


AMITROV, ZHEGALLO

indicative. In many gastropod groups the onset of orna-mentation is clearly fixed after the smooth whorls of theprotoconch. Sometimes, the early ornamentation is dif-ferent from that in most of the teleoconch, and the bor-der between the “intermediate” and “main” zones maybe very distinct. However, in Scalaspira these bordersare not easily found. The initial portions of spiral ribsare very weak, and their place of appearance may beartificially “shifted” when the shell surface is evenslightly tattered or because of the quality of the micro-scope. In some species the “main whorls” may be dis-tinguished from the “intermediate” by the change in thecharacter of ribs from thin and widely spaced to ribbon-shaped, separated by narrow grooves. However, thistransition is gradual, occupying some part of the whorl,whereas in S. suberratica (unlike the closely similar S.alexeevi) the primary ribs from the very beginning areribbon-shaped and the “intermediate” whorls can onlybe distinguished by the presence of axial ridges.

Tembrock indicated the number of “primary spirals”for each Scalaspira species. In some species this num-ber is variable. In addition, the spiral ribs do not appearsimultaneously, and there is an element of subjectivismin the recognition of “primary” ribs. Tembrock did notinclude poorly visible ribs near the sutures in the num-ber of “primary ribs.” However, in different specimensof the same species and in different parts of the sameshell, such a rib may run alternately along the sutureand at a distance from it.

In later whorls growth changes are observed (as theshell grows, the number of ribs always increases), whilevariability increases (number of spiral ribs and the ribwidth-to-intercostal space ratio vary). The speciesS. subgregaria and S. multisulcata are not distin-guished based on the last criteria.

In Table 3 and in the identification key, where theentire range of variability has to be taken into account,the degree of overlap of different species appearsgreater than during the visual examination of the mate-rial. For S. subgregaria and S. multisulcata this con-cerns differences not only in the number of ribs, butalso in the W/H ratio of whorls. In Table 3 the overlapis so large that mentioning this character in the key isuseless, but in fact in most shells of S. subgregariawhorl height is less than half of its width, whereas inS. multisulcata it is greater than half of its width; thelast whorls of the largest specimens show no overlap inthis character.

Table 3 does not contain data on the ornamentationof the base of the shell. In the lower part of the siphonalcanal, the ribs become thin, closely spaced, and oftenfused with each other; and hence, difficult to calculate.In the upper part of the base (below continuation of thesuture), the ribs have approximately the same size,shape, frequency, as in the zones above the suture in thelast whorls. The presence or absence of spiral folds onthe inner surface of outer lip is discussed below. Foldsare present in one of 12 shells of Scalaspira korobkovi,two of nine shells of S. kumsuatensis, and on four of53 shells of S. suberratica. In many Chegan S. alexeevi,

the apertures are incomplete or filled with matrix; how-ever, in one shell, folds are visible, and in several othersthey are certainly absent. In S. multisulcata folds werenot observed in any of hundreds of shells from out-crops, but were observed in two shells from Mangy-shlak bore cores. In the other Transcaspian species,folds were not observed in any specimens. While itcould be suggested that in S. kenderlensis and S. gros-siventrosa they may not have been preserved, or wereunnoticed, in S. subgregaria many shells are reason-ably well preserved, and the absence of the folds onthem is certain.

Usually, folds do not extend far inside the apertureand cover only some areas. It is possible that this isrelated to unfavorable periods in the life of the mollusk.S. suberratica, in which folds occur in zones with vari-cose extensions of the shell wall, provides most supportfor this hypothesis. Unlike many other gastropodgroups, in Scalaspira varices are formed only episodi-cally, are present in a few specimens, and are mostlikely traces of illness.

Tembrock (1968) sometimes mentioned the pres-ence of folds in her species descriptions. However, shedid not attribute much importance to this character.Gründel (1991) agreed with this interpretation, but hementions presence or absence of folds among the char-acters distinguishing subspecies of S. multisulcata (seebelow).

It should be added that shells lacking true folds,including those species in which folds are neverpresent, sometimes also show indistinct spiral eleva-tions and depressions on the inner surface, which usu-ally but not always reflect ribbing on the outer surface.Fractures formed in a decaying shell have the samedirection. Apparently, this is connected to the shellmicrostructure and the way the shell grew.

Another character, pointed out by Gründel is thepattern of the growth line. In some specimens they areslightly incised or wavy (each incision corresponds to aspiral rib). It appears that the degree of incision varieseven within shells of the same species from the samesample. It partly depends on preservation (the incisionsare best visible when the outer layer is slightlyleached). However, in the Transcaspian S. multisulcatathe growth lines are generally considerably more undu-late than in S. subgregaria or in any of specimens ofS. multisulcata that we received from Belgium. Weagree with Gründel that this character can be used incombination with others to distinguish between subspe-cies and species.

IDENTIFICATION KEY TO TRANSCASPIAN SCALASPIRA

1.A. Spiral and axial ornamentations are present……2B. Only spiral ornamentation is present……………32(1A). A. Whorls are relatively strongly convex;

three thin spiral primary ribs are prominent in earlywhorls; axial ribs are approximately the same shape andwidth………………………………Scalaspira korobkovi



B. Whorls are weakly and unevenly convex; spiralribs are numerous and small, axial ribs are ridgelike andlarge……………………………………S. kumsuatensis

3(1B). A. Whorls (at least early) are bent above themiddle. The bent area and the area below possess largewide ribs, usually five. Weak ribs may be developedabove the shoulder……………………………………4

B. Whorls are evenly convex, evenly covered by spi-ral ribs, usually narrow; at least six or seven ribs arepresent…………………………………………………7

4(3A).A. Whorls are weakly convex, the shoulder isdeveloped only in early whorls………………S. alexeevi

B. Whorls are strongly convex, the shoulder ispresent at least until intermediate whorls………………5

5(4B).A. The ribs in the last whorl are clear, evenlycovering the entire shell surface, including thebase………………………………………S. kenderlensis

B. In the upper part of the last whorl, ribs are usuallysmoothened, while they are prominent and large at thebase……………………………………………………6

6(5B).A. The spire is highly conical with an almoststraight generating line: the apical angle is 36°–47°, thegrowth angle of the last whorl is on average smalleronly by 4.5°; W/H ratio of the shell is 38–45%………………………………………………………S. suberratica

B. The spire is shaped like a low cone with a notice-ably convex generating line: the apical angle is 50°–60°,the growth angle of the last whorl is on average by 9°smaller, W/H ratio of the shell is 43–50%………………………………………………………S. grossiventrosa

7(3B).A. Whorls are strongly convex; ornamenta-tion is weak……………………………Scalaspira sp. 1

B. Whorls are weakly convex, ornamentation strong………………………………………………………8

8(7B).A. The spire is conical with weakly convexgenerating line: the apical angle is 36°–50°, the growthangle of the last whorl is on average by 7.7° smaller; sixto ten (usually seven to nine) ribs in intermediate andlater whorls………………………………S. multisulcata

B. The spire is conical with strongly curved gener-ating line: the apical angle is 50°–71°, the growth angleof the last whorl is on average by 18° smaller; 8–15(usually 11–14) ribs are present in the intermediate andlater whorls……………………………S. subgregaria

COMPARISON OF TRANSCASPIAN AND EUROPEAN SPECIES

Table 3 and identification key show the differencesbetween the Transcaspian species. For three new spe-cies, comparisons follow their descriptions. Here, theremaining six taxa are compared with the westernEuropean species.

Shells of five of our species were sent to Tembrockand she published her opinion (Tembrock, 1968). Shefound that Fusus subgregarius Ilyina is a synonym ofScalaspira villana (Philippi). Indeed, the European

specimens that Tembrock identified as S. villana is verysimilar to S. subgregaria. However, Gründel (1991),who revised this group, found it impossible to deter-mine which species was meant from Philippi’s (1847)original description, while the holotype is lost. Appar-ently this is correct, but Gründel (1991) proposed a newname S. multisulcata magdeburgensis Gründel, 1991for the specimens that Tembrock identified as S. vil-lana. If Tembrock’s specimens are identical to the Tran-scaspian species (and it seems so), then they should benamed S. subgregaria (Ilyina, 1955), whereas the nameS. subgregaria remains valid for the Transcaspian spe-cies even if it is different from the European taxon.

As can be seen from Table 3, Tembrock synony-mized Fusus ustjurtensis Ilyina, 1953 with Scalaspiramultisulcata (Nyst, 1845), a view we support. This spe-cies is not very close to S. subgregaria (=? magdebur-gensis), and we, unlike Gründel, believe them to repre-sent different species. However, according to Gründelthe species S. multisulcata includes the subspeciessequens (Warneck, 1926) (= houchei Glibert, 1957) andmarchica Tembrock, 1964. Apparently these are indeedsubspecies of S. multisulcata, with very subtle differ-ences from the type subspecies and each other. Theshells of the type subspecies are 40 mm high, withgrowth lines not undulate, and almost always with foldsin the aperture. The shells of S. multisulcata marchicaare up to 35 mm high, with undulate growth lines and,usually, no folds in the aperture. This subspecies hasslightly more convex whorls and a more strongly deep-ened suture. In S. multisulcata sequens shells are larger(up to 50 mm), also with undulate growth lines andwithout folds in the aperture; whorls in this subspeciesare the most strongly flattened, and ornamentation isweak.

To which subspecies do the Transcaspian specimensbelong? The absence of folds in the aperture and wavygrowth lines distinguish them from the type subspecies.Tembrock, who did not consider these charactersimportant, identified the Transcaspian specimens as thetype subspecies, but it appears that, from their whorlshape and ornamentation, they are close to marchica,whereas they are very much different from the subspe-cies sequens in all characters except size. According toGründel, the three subspecies have different strati-graphic ranges: multisulcata s. s. comes from theLower and Middle Rupelian, marchica comes from theUpper Rupelian, and sequens comes from the Chattian.In the Transcaspian Region S. “ustjurtensis” are foundalmost exclusively in the Chattian (isolated and there-fore doubtful specimens were found in the Rupelian). Itremains unclear whether the Transcaspian specimensbelong to one of the European subspecies or representa separate subspecies of S. multisulcata ustjurtensis.

Tembrock expressed opinions different from ourown on the specimens that Amitrov (1966) identified asAquilofusus suberratica suberratica (Bajarunas),A. suberratica kenderlensis Amitrov and A. grossivent-

16

PALEONTOLOGICAL JOURNAL

Vol. 41

No. 1

2007

AMITROV, ZHEGALLO

Oligocene mollusk assemblages (the Rupelian Ast-sheairyk Formation and the Chattian Karatomak Bedsseparated by the Upper Rupelian Solionovskii Horizon(layers of a brackish water basin with impoverishedfaunal content), whereas the Karatomak Beds are over-lain by the Baigubek Horizon with fauna also indicat-ing reduced salinity and dated by different workersfrom the Upper Oligocene to the Lower Miocene. Pre-viously, if Oligocene marine mollusk shells were foundin this region, they were usually thought to be from theChegan Formation (the only species of

Scalaspira

found in the Chegan Formation was described as

Fusus

sp. and first received a specific name in the presentpaper). In the more westerly region, on the MangyshlakPeninsula, an assemblage of mollusks was recordedfrom the Uzunbas Formation, previously thought bymost workers to have been the same age as the upperChegan Formation. At present the prevailing opinionsuggests that the Upper Eocene (equivalents of the Che-gan Formation) on Mangyshlak is represented by theAdaevskaya Formation (carbonates virtually lackingmollusks), whereas the Uzunbas Formation and some

Table 1.

Distribution of

Scalaspira

in the Transcaspian Region

Series Subseries Stage Mangyshlak and southwestern UstyurtNorthern Ustyurt,

northern Aral Region,Turgai Depression

Mio

cene

Low

er

Aqu

itani

an

Bai

gube

kH

oriz

on

Scal

aspi

ra

sp.

1

Olig

ocen

e

Upp

er

Cha

ttian

Kar

agie

Form

atio

n

S

.

mul

tisu

lcat

a

Kar

atom

ak B

eds

S

.

mul

tisu

lcat

aS

.

koro

bkov

i

S

.

kum

suat

ensi

s

Low

er

Rup

elia

n

Solionovskii Horizon

Ken

derl

i fau

nal

asse

mbl

age

S

.

kend

erle

nsis

(

S

.

mul

tisu

lcat

a

?)

Ast

shea

iryk

For

mat

ion

uppe

r pa

rt o

fth

e fo

rmat

ion,

sand

s

S

.

gros

sive

ntro

saS

.

subg

rega

ria

Uzu

nbas

and

Kul

andy

faun

alas

sem

blag

es

S

.

sube

rrat

ica

S

.

subg

rega

ria

(

S

.

mul

tisu

lcat

a

?)

low

er p

art o

fth

e fo

rmat

ion,

clay

s

S

.

sube

rrat

ica

S

.

subg

rega

ria

Eoc

ene U

pper

Pria

boni

an

Che

gan

Form

atio

n

S

.

alex

eevi

Mid

dle

Bar

toni

an



rosa Amitrov. Perhaps, this is partly related to the factthat the Transcaspian material which she saw was notwell preserved. We still do not have shells with proto-conchs for Scalaspira kenderlensis and S. grossivent-rosa, whereas in S. suberratica protoconchs are pre-served in only a few specimens (types, which we couldnot send abroad). A photograph of one of these pub-lished by Tembrock as a drawing (Tembrock, 1968,pl. 9, fig. 5) was also not of sufficient quality. Tembrocksaw on the shell only two “primary spirals” and thoughtthat this species is similar to S. erratica (Koninck). Infact S. suberratica has five primary “spirals” and fiveribs remain in the later whorls, whereas in S. erraticatwo large ribs are present even in later whorls.

Tembrock considered the species S. kenderlensisdistant from S. suberratica and believed it to be close tothe British species S. regularis (Sowerby). These spe-cies are similar in general shell shape and the strongconvexity of whorls, but their ornamentation is sharplydifferent (shells of S. regularis possess distinct axialribs). We noted (Amitrov, 2005) that the Kenderli Fau-nal Assemblage, despite its peculiarity, is still similar tothe synchronous and slightly earlier assemblages ofneighboring regions; the origin of the Kenderli Sca-laspira from the Uzunbas S. suberratica seems quiteprobable, whereas the immigration of the S. regularisgroup to the Kenderli basin would have appeared odd.Even morphologically, the Kenderli specimens are sosimilar to the Uzunbas–Kulandy species that at firstthey were described as a subspecies. Later, taking intoaccount Tembrock’s opinion we began consideringthem as a separate species.

Scalaspira grossiventrosa, in contrast, was from thebeginning described as a separate species because,based on the material available, it was more clearly sep-arated from S. suberratica. However, it seems possiblenow that this is not even a subspecies, but in Tem-brock’s terminology, a facial variety. In the Ustyurt,S. suberratica is found in the clayey facies in the lowerpart of the Astsheairyk Formation, whereas the morethick walled, low S. grossiventrosa (the name means“with a large belly”) come from the sandy facies of theupper part of the formation. The majority of our speci-

mens were collected on Mt. Karashoky, but the shellsfigured in the dissertation of A.I. Korobkov as Aquilo-fusus suberraticus also come from this locality (possi-bly from more fine-grained rocks). Judging from theapical angle (42° and 47°) these specimens should morelikely to be placed near S. suberratica than near S. gros-siventrosa. It is possible that the discovery of bettermaterial will allow a clearer separation of these formsor a justified synonymy. Tembrock did not find reliablecharacters in S. grossiventrosa distinguishing it fromS. erratica, but it seems that the Upper Astsheairykspecimens are even less similar to S. erratica than thetypical S. suberratica. The species from the BaigubekDeposits that we identify as Scalaspira sp. 1 was deter-mined by A.I. Korobkov as Aquilofusus aff. peregerBeyrich, but it seems that this species is not similar theNorth European Neogene species S. pereger, which hasaxial ornamentation (although weak) and relativelystrong, irregular spiral ornamentation.

SYSTEMATIC PALEONTOLOGYFamily Buccinidae Rafinesque, 1815

Genus Scalaspira Conrad, 1862Scalaspira alexeevi Amitrov et Zhegallo, sp. nov.

Plate 3, figs. 1–4

Fusus sp. nov. ?: Ovechkin, 1954, p. 80, pl. 11, figs. 11 and 12.Fusus sp. nov.: Alexeev, 1963, p. 111, pl. 21, figs. 1 and 2.Fusus sp. a: Korobkov, 1967, p. 68, pl. 1, fig. 25.E t y m o l o g y. In memory of A.K. Alexeev, spe-

cialist on the Paleogene mollusks of the TranscaspianRegion.

H o l o t y p e. PIN, no. 1470/41255; Kazakhstan,Turgai Depression, Atambas-Chink; Upper Eocene,Chegan Formation.

D e s c r i p t i o n. The shell is spindle-shaped, up to83 mm high (possibly even higher). W : H = 33–47%,AH : H = 52–61%. The spire is conical, with a generat-ing line varying from weakly convex to weakly concave(on average straight). The growth angle of early whorlsis 30°–51°, the growth angle of the last whorl is on aver-age smaller than one degree, but can be greater (up to54°). The whorl growth is regular. WH : WW = 47–64%.

E x p l a n a t i o n o f P l a t e 3All specimens are housed in the Depository of the Paleontological Institute of the Russian Academy of Sciences.Figs. 1–4. Scalaspira alexeevi sp. nov. Upper Eocene, Chegan Formation: (1) holotype PIN, no. 1470/41255, from the side oppositeto the aperture, ×1; Turgai Depression, Atambas-Chink; (2) specimen PIN, no. 1470/25011, apertural view, ×1.5, northern AralRegion, Mt. Termenbes; (3) specimen PIN, no. 1470/2657, early whorls, (3a) ×12, (3b) ×23, the same locality; (4) specimen PIN,no. 1470/39216, from the side opposite to the aperture, ×4, Turgai Depression, Chelkar-Nura Chink.Figs. 5 and 6. Scalaspira suberratica (Bajarunas, 1912). Lower Oligocene: (5) specimen PIN, no. 1470/48025, from the side oppo-site to the aperture, ×1.5, ? Mangyshlak, Uzunbas Formation; (6) specimen PIN, no. 1470/1680, early whorls, (6a) ×9.5, (6b) ×23,Mangyshlak, Uzunbas ravine, Uzunbas Formation.Figs. 7 and 8. Scalaspira grossiventrosa (Amitrov, 1966). Lower Oligocene, northern Ustyurt, upper part of the Astsheairyk For-mation: (7) holotype PIN, no. 1470/929, apertural view, ×1, Astsheairyk ravine (= Amitrov, 1966, pl. 2, fig. 11); (8) specimen PIN,no. 1470/1686, apertural view, ×1, Mt. Karashoky (= Amitrov, 1966, pl. 2, fig. 10).Figs. 9 and 10. Scalaspira kenderlensis (Amitrov, 1966). Lower Oligocene, Mangyshlak, Kenderli solonchak playa: (9) holotypePIN, no. 1470/1684, (9a) from the side of the outer lip, ×1, (9b) apertural view, ×1 (= Amitrov, 1966, pl. 2, fig. 8 = Amitrov, 1971,pl. 2, fig. 5); (10) specimen PIN, no. 1470/1683, from the side opposite to the aperture, ×1 (= Amitrov, 1966, pl. 2, fig. 9).



The whorls are weakly convex, in early whorls a moreor less noticeable shoulder occurs above the middle ofthe whorl, although the convexity remains somewhatirregular. The shell possesses only spiral ribs. Judgingfrom the specimen in which the early whorls are betterpreserved (Pl. 3, fig. 3), three identical ribs appear first,and soon the fourth similar rib appears from under thesuture. The upper rib runs above the mid-whorl and cor-responds to the shoulder. Later, between it and the sec-ond rib, two weaker ribs appear. In the subsequentwhorl they are the same size as the four primary ribs.One rib may appear before the shoulder. All ribs arethin at first, separated by considerably wider spaces, butthey gradually become wide, ribbonlike, whereas thespaces in the last whorls are usually slightly narrowerthan the ribs. In the whorls of the spire and in the lastwhorl above the continuation of the suture, the numberof ribs is usually five to seven, sometimes four, but mayoccasionally increase to ten due to the intercalation ofsecondary ribs. On the base of the shell, the ribs areapproximately of the same shape and size as in theupper part of the last whorl. Some large shells, espe-cially in their last whorls, are almost smooth, but evenin these ribbing is present on the base. In some speci-mens, thin folds (about 12) are present on the inner sur-face of the outer lip of the aperture.

M e a s u r e m e n t s o f t h e h o l o t y p e. H =64 mm, W = about 27 mm, AH = about 38 mm, AW =13 mm, apical angle is 39°, growth angle of the whorlis 47°, the number of spiral ribs in the early whorls is six,in the penultimate whorl there are eight ribs per whorl.

C o m p a r i s o n. Of all know Scalaspira species,the Chegan species most closely resembles the Rupe-lian S. suberratica (which is apparently its directdescendant). They share such characters as an irregularconvexity of the whorl, the presence of a shoulder inearly whorls, and a low number of ribs. However,already in the early whorls, the shoulder in S. alexeeviis weaker, whereas the convexity in the last whorls ismore regular. Judging from the few specimens withpreserved first postembryonic whorls, the ribs in S. sub-erratica from the very beginning are wide and ribbon-like, whereas in S. alexeevi, the ribs remain thin for

some time. The new species differs even more stronglyfrom S. grossiventrosa and S. kenderlensis. In S. gros-siventrosa the shell is relatively low, with a noticeablyconvex generating line, whereas in S. kenderlensis thelast whorls are covered by ribs that show no trendtoward smoothening. In S. erratica in early and usuallyin last whorls two strong ribs are sharply predominant.Even if the Transcaspian species are related to S. errat-ica, as was believed by Tembrock, S. alexeevi is lesssimilar to it than S. suberratica and S. grossiventrosa.This species is distinguished from S. subgregaria andS. multisulcata by the presence of a shoulder in theearly whorls and in having fewer ribs. The Chegan spe-cies is more similar to S. multisulcata from the Chattianof the Transcaspian Region than to the Rupelian S. sub-gregaria, from which it is also distinguished by theshape of the spire (in S. subgregaria the generating lineof the cone is strongly convex) and in the number of ribs.

O c c u r r e n c e. The upper Middle? and UpperEocene, Chegan Formation; Kazakhstan.

M a t e r i a l. Two hundred and ten specimens; ofwhich 203 are from the Turgai Depression (Chelkar-Nura Chink, Atambas-Chink, Mt. Atambas); others arefrom the northern Aral Region: Mt. Termenbes (fivespecimens), Altan-Chokusu Uplift (one specimen),Tuguzken Depression (one specimen). Almost all shellsare to some extent damaged and worn, none has a pro-toconch.

Scalaspira korobkovi Amitrov et Zhegallo, sp. nov.

Plate 4, figs. 10–12

E t y m o l o g y. In honor of A.I. Korobkov, special-ist in Cenozoic mollusks.

H o l o t y p e. PIN, no. 1470/29335; Kazakhstan,coast of the Aral Sea, Kumsuat Bay; Upper Oligocene,Karatomak Beds.

D e s c r i p t i o n. The shell is spindle-shaped, up to35 mm high. W : H = 40–49%, AH : H = 54–62%. Thespire is shaped like a cone with an almost straight gen-erating line: the growth angle of the early whorls is40°–47° (in one specimen 54°), the growth angle of the

E x p l a n a t i o n o f P l a t e 4Figs. 1–5. Scalaspira subgregaria (Ilyina, 1953). Lower Oligocene; (1) specimen PIN, no. 1470/2702, from the side opposite to theaperture, ×2, Mangyshlak, Kulandy Cliffs (= Amitrov, 1971, pl. 2, fig. 2); (2) specimen PIN, no. 1470/47626, from the side oppositeto the aperture, ×2, Mangyshlak, Kulandy Cliffs; (3) specimen PIN, no. 1470/784, from the side opposite to the aperture, ×2, north-ern Ustyurt, Astsheairyk Ravine, Astsheairyk Formation; (4) specimen PIN, no. 1470/1005 (juvenile), (4a) from the side oppositeto the aperture, ×13, (4b) early whorls, ×17.5, southern Aral Sea Region, from a borehole of the Karakol’ Branch of SGPK;(5) specimen PIN, no. 1470/930, apertural view, ×1, northern Ustyurt, Mt. Tamdy, Astsheairyk Formation.Figs. 6–9. Scalaspira multisulcata (Nyst, 1845). Upper Oligocene: (6) specimen PIN, no. 1470/28562, from the side opposite to theaperture, ×1.5, northern Aral Sea Region, Kumsuat Bay, Karatomak Beds; (7) specimen PIN, no. 1470/28564, apertural view, ×1.5,the same locality; (8) specimen PIN, no. 1470/28580, apertural view, ×2, the same locality; (9) specimen PIN, no. 1470/973, earlywhorls, ×12, southern Aral Sea Region, borehole of the Tashauz Branch of SGPK.Figs. 10–12. Scalaspira korobkovi sp. nov. Upper Oligocene, northern Aral Sea Region, Kumsuat Bay, Karatomak Beds: (10) holo-type PIN, no.1470/29335, from the side opposite the aperture, ×2; (11) specimen PIN, no. 1470/29333, apertural view, ×2;(12) specimen PIN, no. 1470/29342, from the side opposite to the aperture, ×3.Figs. 13 and 14. Scalaspira kumsuatensis sp. nov. Upper Oligocene, northern Aral Sea Region, Kumsuat Bay, Karatomak Beds:(13) specimen PIN, no. 1470/29350, from the side opposite to the aperture, ×2; (14) holotype PIN, no. 1470/29349, apertural view, ×2.

26


AMITROV, ZHEGALLO

last whorl is 34°–45°; the difference between theseangles is on average 3°. WH : WW = 50–69%; this ratioslightly decreases from earlier to later whorls. Whorlsare relatively strongly convex. The early whorls quiteclearly show a shoulder above the middle of the whorlthat becomes smoothened in the last whorls in largespecimens, but the convexity remains irregular.

The ornamentation is represented by spirals andaxial ribs. The early whorls possess three spiral ribs(the upper rib is on the shoulder). The ribs are large, allthe same size, and are narrower than the intercostalspaces. Later, secondary ribs appear in the spaces andabove the shoulder. The secondary ribs quickly reachthe size of the three primary ribs. In larger shells, thetotal number of ribs in the penultimate whorl and in thelast whorl above the continuation of the suture reaches10. Similar ribs cover the base, where there are 12 ofthem. The axial ribs are usually more distinct in theearly whorls, where in their size and shape they are sim-ilar to spiral ribs (also narrow, with wider spaces) andform a regular lattice crossing the spiral ribs. In the lastwhorls, the axial ribs may become smoothened, loseregularity, and become very similar to growth lines.The number of the axial ribs is from 12 to 19 per whorl.On average it becomes slightly larger from the early tothe last whorls. In one of the specimens in our collec-tion the inner surface of the outer lip possesses 12 thinfolds of varying size.

M e a s u r e m e n t s o f t h e h o l o t y p e. Theholotype is at least 34 mm high and 13.6 mm wide;WH = about 21 mm; WW = 7.5 mm; growth angle ofthe early whorls is 47°, of the last whorl 42°, the num-ber of spiral ribs in early whorls is 4–5, 8 ribs in thepenultimate whorl above the suture, 12 ribs on the base,13 axial ribs in early whorls, and up to 19 ribs per whorlin later whorls.

C o m p a r i s o n. This species is distinguished fromother Transcaspian species of Scalaspira, except forS. kumsuatensis, by the presence of axial ribs. It differsfrom S. kumsuatensis also in the shape of the whorl (thepresence of the shoulder in early whorls and in the morestrongly developed and more irregular convexity in thelater whorls) and in the ornamentation, both spiral (inthe early whorls three large ribs instead of numerousweak ribs) and axial (the ribs are thin rather than wideand rounded ridgelike). Korobkov (1965) identified thisform as Aquilofusus elegantulus tricarinatus. However,the species Scalaspira elegantula (Philippi, 1843) fromthe Chattian of northern Europe retains a sharp shoul-der up to the later whorls and has only two spiral ribs oreven only one (the second may run below the suture andbecome visible only in the last whorl). In S. tricarinata(Koch et Wiechmann, 1872) (according to Tembrock,an independent species that also comes from the Chat-tian of northern Europe) there are three spiral ribs, butthis number remains the same in the later whorls; andneither the shoulder nor the axial ribs become smooth-ened. In its shape and ornamentation of the later whorls,

the new species resembles some Neogene species,especially S. semiglabra (Beyrich, 1856), but the latterspecies and other similar species have two strong spiralribs, whereas the third (upper), when present, is muchweaker.

M a t e r i a l. Twelve shells from the Karatomak areain the Kumsuat Bay. All shells are to some extent dam-aged, and none has a protoconch.

Scalaspira kumsuatensis Amitrov et Zhegallo, sp. nov.

Plate 4, figs. 13 and 14

E t y m o l o g y. From the Kumsuat Bay in theAral Sea.

H o l o t y p e. PIN, no. 1470/29349; Kazakhstan,coast of the Aral Sea, Kumsuat Bay; Upper Oligocene,Karatomak Beds.

D e s c r i p t i o n. The shell is spindle shaped, up to41 mm high, W : H = 37–43%, AH : H = 51–60%, thespire is in the shape of a cone with a weakly convexgenerating line: the growth angle in the early whorls is42°–47°, that of the last whorl is on average by 7°smaller. WH : WW = 49–66%, is almost independent ofthe size of the whorl. Whorls are weakly, evenly convex.

The shell possesses spiral and axial ribs. The spiralribs are weak and densely spaced. There are five toseven primary ribs in the intermediate and later whorls,but even weaker secondary ribs and, in larger speci-mens, tertiary ribs intercalate. Hence, the total numberof ribs may increase fourfold. The axial ribs are wide,ridgelike, usually 8 to 11 per whorl, in one shell even16. In some shells, the inner surface of the outer lip hasabout eight folds.

M e a s u r e m e n t s o f t h e h o l o t y p e. H =24.8 mm, W = 9.8 mm, AH = 13.6 mm, AW = 4.2 mm,the growth angle in the early whorls is 47°, that of thelast whorl is 33°, the number of spiral ribs is 5 × 2 in theearly whorls and 6 × 4 in the later whorls, and the num-ber of axial ribs is 10 per whorl.

C o m p a r i s o n. The comparison with S. korobkoviis above. The new species is distinguished from otherTranscaspian species by the presence of axial ribs. It isdistinguished from the northern European speciesS. deshayesi (Nyst, 1845), which was identified byKorobkov as the Transcaspian species, by the cleardivision of spiral ribs into the primary and secondaryribs. It differs from S. waeli (Nyst, 1852) in the samecharacter, and in the higher, less convex whorls andmore densely spaced axial ribs.

R e m a r k s. R. Janssen and J. Gründel (Germany)examined our material and agreed that this species isdifferent from the northern European species, and sug-gested that it possibly belongs to Streptochetus ratherthan to Scalaspira. Similar species of both genera aredistinguished based on protoconchs, which are not pre-served in our specimens.

O c c u r r e n c e. Upper Oligocene, KaratomakBeds; Kazakhstan.



M a t e r i a l. Nine specimens, of which seven comefrom the Karatomak area, Kumsuat Bay, northern AralSea Region, and two specimens come from theAshchik-Taipak area, northern Ustyurt.

ACKNOWLEDGMENTS

The manuscript of this paper and the materialdescribed was examined and commented on by R. Jan-ssen and J. Gründel (Germany) and by L.B. Iljina,L.A. Nevesskaja, S.V. Popov, and A.A. Shevyrev, ourcolleagues from the Laboratory of Mollusks (Paleonto-logical Institute, Russian Academy of Sciences).A.V. Guzhov helped in the preparation of the manu-script for publication. Some specimens were photo-graphed by V.T. Antonova. We are very grateful to allthese people.

The study was supported by the Russian Foundationfor Basic Research, project no. 04-04-48703.

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Scalaspira (Gastropoda) from the Paleogene of the Transcaspian Region