Early Triassic Conchostracans (Crustacea: Branchiopoda) from the terrestrial Permian–Triassic boundary sections in the Moscow syncline

Palaeogeography, Palaeoclimatology, Palaeoecology 429 (2015) 22–40

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Palaeogeography, Palaeoclimatology, Palaeoecology

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Early Triassic Conchostracans (Crustacea: Branchiopoda) from theterrestrial Permian–Triassic boundary sections in the Moscow syncline

Frank Scholze a,d,⁎, Valeriy K. Golubev b,d, Grzegorz Niedźwiedzki c, Andrey G. Sennikov b,d,Jörg W. Schneider a,d, Vladimir V. Silantiev d

a Geological Institute, Technische Universität Bergakademie Freiberg, Bernhard-von-Cotta-Str. 2, 09599 Freiberg, Germanyb Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya str. 123, Moscow, 117997 Russiac Department of Organismal Biology, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Swedend Kazan Federal University, Kremlyovskaya str. 18, 420008 Kazan, Russia

⁎ Corresponding author at: TU Bergakademie Freiberg GPalaeontology/Stratigraphy Bernhard-von-Cotta-Str. 20049 3731 393812.

E-mail addresses: [email protected] (F(V.K. Golubev), [email protected] (G. Nied(A.G. Sennikov), [email protected] ([email protected] (V.V. Silantiev).

http://dx.doi.org/10.1016/j.palaeo.2015.04.0020031-0182/© 2015 Elsevier B.V. All rights reserved.

a b s t r a c t
a r t i c l e i n f o
Article history:Received 29 January 2015Received in revised form 20 March 2015Accepted 6 April 2015Available online 15 April 2015

Keywords:ConchostracaSpinicaudataBiostratigraphyEarly TriassicPermian–Triassic boundaryMoscow syncline

The Permian–Triassic boundary marks the greatest mass extinction in Earth's history. In order to understand thereal causes of this severe extinction event, multidisciplinary investigations around the globe are required. Here,the terrestrial Permian–Triassic boundary sections in the Vladimir region, Central Russia, were sampled bed-by-bed for conchostracan study. In the Early Triassic intervals the following taxa were recognized for the firsttime: Cornia germari (Beyrich, 1857), Euestheria gutta (Lutkevitch, 1937), Magniestheria mangaliensis (Jones,1862), Palaeolimnadiopsis vilujensis Varentsov, 1955, and RossolimnadiopsisNovozhilov, 1958. The wide distribu-tion of C. germari demonstrates their high value for biostratigraphy, since this species was also reported from theLower Buntsandstein Subgroup in the Germanic Basin as well as from Early Triassic deposits in Hungary, Green-land and Siberia. The assumption of an Early Triassic age of the studied sections is also supported by associatedTupilakosaurus bone fragments, which point to the Tupilakosaurus wetlugensis Zone in the earliest Triassic.

© 2015 Elsevier B.V. All rights reserved.

1. Introduction

The Permian–Triassic boundary (PTB) marks the greatest mass ex-tinction in Earth's history. The strongest effects of the end-Permianmass extinction on the biosphere are visible in the marine realm,where over 90% of species died out (e.g., Erwin, 1994). The interval ofthe extinction is less than 200,000 years (Shen et al., 2011) and debatesabout the cause include oceanic anoxia (e.g., Wignall and Twichett,1996), volcanism (e.g., Reichow et al., 2002), asteroidal or cometary im-pact (e.g., Becker et al., 2001), global cooling (e.g., Roscher et al., 2011),global warming (e.g., Sun et al., 2012), and various combinations ofthese processes (e.g., Benton and Twichett, 2003). The terrestrial systemsuffered as well, but the extinction was not as severe as in the oceans(e.g., Erwin, 2006). The investigation of extinction pattern in terrestrialenvironments is primarily hampered by the inadequate determinationof the PTB in nonmarine environments. The lack of volcanic ash bedsfor isotopic age determination of the critical interval in several of the

eological Institute, Department09599 Freiberg Germany. Tel.:

. Scholze), [email protected]źwiedzki), [email protected]),

best investigated terrestrial PTB sections such as in the European partof Russia is challenging the search of alternative time markers likeprominent peaks in carbon isotopic values (e.g., Aref'ev et al., 2015),magnetostratigraphic reversals (e.g., Taylor et al., 2009), and abruptfacies changes in the depositional system (e.g., Newell et al., 2010).

The sedimentary successions of the Moscow syncline in the vicinityof the towns of Vyazniki and Gorokhovets, Vladimir region, CentralRussia (Fig. 1A), provide a rare chance to study a nonmarine ecosystemof Late Permian to Early Triassic age. Conchostracans represent one ofthe most abundant faunal elements among a diverse assemblage ofnonmarine fossils consisting of tetrapods, fishes, insects, ostracods,bivalves, and plant remains (e.g., Golubev, 2000; Golubev et al., 2012a,b; Krassilov and Karasev, 2008, 2009; Kukhtinov et al., 2008; Owockiet al., 2012; Sennikov and Golubev, 2005, 2006, 2010a,b, 2012, 2013a,b). They form a paraphyletic group of Branchiopoda, now divided intothe monophyletic Laevicaudata, Spinicaudata and Cladoceromorpha(Richter et al., 2007). Herewe dealwith Spinicaudata, but use for conve-nience the term Conchostraca.

The first conchostracans from Vyazniki were determined to beRossolimnadiopsis marlierei by Novozhilov (1958). Further finds ofPseudestheria suchonensis, Pseudestheria sp., Loxomicroglypta sp. andConcherisma sp. were reported by Sennikov and Golubev (2005,2006). Although conchostracans generally show high value for biostra-tigraphy in nonmarine sedimentary environments (e.g., Schneider et al.,

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Fig. 1. Geographic position of the studied sections. A,map showing European Russia; B and C, positions of the study areas around Vyazniki and Gorokhovets; D, positions of the sections inthe ravine outcrops near Arefino and Slukino. Names of the studied Late Permian (Zhukovian Regional Stage) and Early Triassic (Vokhmian Regional Stage) section intervals are: 1,Fedurniki sand pit; 2, Zhukov Ravine (section no. 1236); 3, Zhukov Ravine (section no. 1029); 4, Arefino Ravine (section no. 1225); 5, Staroye Slukino.

23F. Scholze et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 429 (2015) 22–40

2005, for the Late Paleozoic; Kozur andWeems, 2010, for the Early Me-sozoic), biostratigraphic subdivisions and correlations based onconchostracans of Early Triassic deposits in the Moscow syncline havenot yet been established.

Recently, significant progress has been achieved and increasingnumbers of biostratigraphic studies of Late Permian and Early Trias-sic conchostracans have been published from Germany (e.g., Kozurand Weems, 2010), Poland (Żyła et al., 2013), western Siberia(Chunikhin, 2009), northern China (e.g., Zhang et al., 2012), Kenya(Shen, 2006), India (e.g., Gosh, 2012), Brazil (e.g., Ferreira-Oliveiraand Rohn, 2010) and Argentina (e.g., Tassi et al., 2013). Here, wellpreserved conchostracans from the Moscow syncline will be usedfor a first attempt to correlate earliest Triassic sediments of the Moscowsyncline and the Germanic Basin, which have been previously correlatedwith the global marine standard scale (e.g., Bachmann and Kozur, 2004;Taylor et al., 2009).

2. Locality

In the vicinity of the towns of Vyazniki and Gorokhovets threetransitional Late Permian to Early Triassic sections (Fedurniki sand pit,Zhukov Ravine, Arefino Ravine) and one Early Triassic section (StaroyeSlukino) have been sampled bed-by-bed for conchostracans (Fig. 1B).The Fedurniki section is exposed in an abandoned sand pit locatedapproximately 6.5 km east-southeast from the center of Vyazniki(Sennikov and Golubev, 2013b). The ravine outcrops near Arefino and

Staroye Slukino (Golubev and Sennikov, 2010; Newell et al., 2010;Sennikov and Golubev, 2010a,b, 2012, 2013a) consist of hand-dugtrenches located in incised valleys approximately 4 km southwest ofthe center of Gorokhovets (Fig. 1C, D).

3. Geologic setting and stratigraphy

Continental Permian–Triassic sequences in the European part ofRussia range in age from the late Early Permian (Kungurian) to MiddleTriassic (Ladinian), a time span of some 35 Ma (Newell et al., 2010).The profiles of the Permian and Triassic continental deposits are wellexposed in some parts of the Russian Platform, about 100–150 mthick, and are especially available for field research at the Vyazniki andGorokhovets sites. The position of the PTB is not yet clearly defined forthis area and all suggestions were based mainly on lithological criteriasupported by some data from ostracod and vertebrate occurrences(Newell et al., 2010; Sennikov and Golubev, 2012). We are aware thata direct and convincing correlation of the PTB of the global marinestandard scale (Shen et al., 2013) with the continental profiles in thestudy area is still missing. Here we follow Sennikov and Golubev(2012) in the designation of the PTB as discussed below.

The Late Permian to Early Triassic sections around Vyazniki andGorokhovets record a sedimentary succession of muddy playa-lakedeposits, which were abruptly overlain by sand-grade major channeldeposits near the PTB (Newell et al., 2010; Strok et al., 1984). This pro-nounced change in the sediment flux was interpreted by Newell et al.

Fig. 2. Stratigraphic subdivision and correlation of profiles based on Strok et al. (1984), Newell et al. (2010), and new data from the studied sections around Vyazniki and Gorokhovets.Conchostracan-bearing horizons are indicated. PTB marks the position of the Permian–Triassic boundary according to Sennikov and Golubev (2010a, 2010b, 2012) and Golubev et al.(2012a, 2012b).

24 F. Scholze et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 429 (2015) 22–40

(2010) to be related to events of increasing sediment delivery from the800 km distant UralMountains caused by the destruction of the vegeta-tion cover in upland catchment areas related to themass extinction at orclose to the PTB. Later, A.G. Sennikov and V.G. Golubev demonstratedthat the base of the sand channels near Gorokhovets, previouslyassigned to the Early Triassic, yielded terminal Permian (Zhukovian Re-gional Stage) tetrapod, fish and ostracod faunas (Golubev and Sennikov,2010; Golubev et al., 2012a,b; Sennikov and Golubev, 2010a,b, 2012). Incontrast to the previously assumed position of the PTB (Newell et al.,2010; Strok et al., 1984), the present one does not represent an erosion-al contact between lacustrine claystones and channel sandstones, but issituated somewhat above the lowermost sandstone channels in thesesections (Fig. 2). Therefore, the change in the depositional environmentstarted before the PTB.

In the study area latest Permian (Zhukovian Regional Stage) depositsconsist predominantly of lacustrine claystones and limestones aswell as

floodplain claystones, siltstones, sandstones and fluvial sandstones be-longing to the Obnora Formation. A correlative limestone bed, which isinterpreted as a lacustrine deposit, provides a lithostratigraphic link be-tween the outcrops in the Zhukov Ravine, and in the ravines close to thevillages Arefino and Staroye Slukino (Fig. 2). The deposits of theZhukovian Regional Stage are characterized by a diverse fauna contain-ing conchostracans, ostracods, bivalves, gastropods, fishes, and large tet-rapods (e.g., Golubev et al., 2012a,b). In contrast, the Early Triassic partsof the studied sectionswere built upmainly of channel facies sandstoneswith intercalations of conchostracan-bearing floodplain claystones. Inthe Vokhma Formation fluvial sandstones and floodplain claystonesshowing bioturbation and bleaching by fossil plant roots are characteris-tic of the Vokhmian Regional Stage. They occur frequently in the EarlyTriassic intervals of the investigated sections. Due to the appearancesof vertebrate remains, including Tupilakosaurus sp. in sandstone bedsof the Vokhmian Regional Stage (e.g., Sennikov and Golubev, 2006,

Fig. 3. Lithology, stratigraphic subdivision and fossil content of the studied profiles around Vyazniki and Gorokhovets. Conchostracan-bearing horizons are indicated. PTB marks theposition of the Permian–Triassic boundary drawn at the base of the Tupilakosaurus wetlugensis Zone.


2012), the Zhukov Ravine sections can be correlated with the Early Tri-assic Tupilakosaurus wetlugensis Zone of the Russian Regional Scale(e.g., Golubev et al., 2012a,b). The stratigraphic subdivisions and correla-tions of the studied sections are shown in Fig. 3.

3.1. Fedurniki sand pit

At this site a 6-m-thick section of latest Permian sandy deposits iscovered by 2–3 m of conglomerates and sandstones as well as 3 m ofred mudstones, siltstones and fine-grained sandstones of Early Triassicage. The lowermost part of Triassic sediments at this site is marked bya characteristic mudstone–claystone horizon with desiccation cracks,located above sandy deposits (Fig. 4). Conchostracans were found inmudstones and siltstones in the upper part of the exposed profileabout 5 m above the PTB (Figs. 3, 5).

3.2. Zhukov Ravine (section nos. 1236 and 1029)

The Zhukov Ravine section is located ca. 2.5 km south-west ofGorokhovets, and comprises a ca. 60 m thick section of Late Permian–Early Triassic deposits. In the upper part of the Zhukov Ravine a well-cemented intraclast sandstonemarks an abrupt change frommudstonesand occasional limestone to a succession dominated by orange-brown,fine- to medium-grained, cross-bedded, weakly cemented sandstonewith mudstone–siltstone intercalations. The PTB is drawn within thesandstones by the first occurrence of Tupilakosaurus remains. The EarlyTriassic conchostracan material was collected in the uppermost part of

the exposed section from the mudstone and clayey layers locatedbetween sandy deposits about 2.5 to 3.5 m above the PTB (Figs. 3, 6).

3.3. Arefino Ravine

At this site a 5 m-thick Early Triassic succession of orange-brown,greenish, yellowish and reddish-brown, weakly consolidated, fine- tocoarse-grained sandstone with mudstone and siltstone intercalationsis exposed (Fig. 7). Conchostracanswere found in two locally developedclayish intervals.

3.4. Staroye Slukino

The 1.60 m-thick Staroye Slukino section consists of brownsandstones and conglomerates with local centimeter to decimeterthick intercalations of orange-brown and grayish red siltstonesof Early Triassic age. The conchostracans occur in horizontallybedded, fine sandy siltstones in the lower and middle parts of thesection (Fig. 3).

4. Methods

During ongoing field campaigns the Late Permian to Early Triassicsections around Vyazniki and Gorokhovets have been investigated indetail for lithology, lithofacies, stratigraphy and ecosystem reconstruc-tion (Golubev et al., 2012a,b; Kukhtinov et al., 2008; Newell et al.,2010; Owocki et al., 2012; Sennikov and Golubev, 2006; Strok et al.,

Fig. 4. Characteristic sediments of the Vokhma Formation in the Fedurniki sand pit section. A, the basal part of the Vokhma Formation, Vokhmian Regional Stage (Early Triassic), ismarkedby a claystone horizon with greenish gray desiccation cracks; B, detailed view on the greenish gray bleached desiccation cracks; C, poorly sorted conglomerate with claystone clasts at thebase of the Vokhma Formation. Scale bars: A, 40 cm; B, 47 cm (total length of the shovel); C, 10 cm.

Fig. 5.Upper part of the Fedurniki sand pit section, Vokhma Formation (Vokhmian Regional Stage; Early Triassic). A, position of the two conchostracan-bearing horizons inmainly reddishclaystones; B, supposed plastic deformation (marked by arrows) of reddish claystones with partial greenish gray bleaching; C, close-up of the lower conchostracan horizon showing redcolored claystones with partial greenish gray bleaching. Scale bars: A, 47 cm (total length of the shovel); B, 20 cm; C, 10 cm. (For interpretation of the references to color in this figurelegend, the reader is referred to the web version of this article.)


Fig. 6. Sediments, stratigraphy and conchostracan-bearing beds in the Zhukov Ravine section. A, the base of the Vokhma Formation ismarked by fluvial sandstones overlying reddish col-ored claystones of a playa-lake facies of the Obnora Formation (Zhukovian Regional Stage, Late Permian) (section no. 1027A); B and C, sandstoneswith positions of conchostracan-bearinghorizons in intercalated reddish claystones 2.50m above the base of the Early Triassic Vokhmian Regional Stage in the Zhukov Ravine (section no. 1029). Scale bars: A, B, 42 cm (length ofthe pickaxe); C, 100 cm. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)


1984). Conchostracans were collected bed-by-bed in the hand-dugtrenches along steep ravine flanks in 2008, 2010, 2012 and 2013 injoint Russian–Polish–German field work (Scholze, 2012; Tałanda et al.,2010).

More than 1000 specimens (collections of the Geological Institute,TU Bergakademie Freiberg and the Institute of Paleobiology, Polish

Fig. 7. Sediments and fossil content of the Arefino Ravine section. A and B, conchostracans occconchostracans. C and D, succession of red to reddish gray colored sandstones of the Vokhmaand D, 20 cm. (For interpretation of the references to color in this figure legend, the reader is r

Academy of Science, Warzawa) from 10 exposures and 17 horizons ofLate Permian to Early Triassic age were collected, including two aban-doned sand pits (Bykovka Quarry and Fedurniki sand pits in theVyazniki region), and artificial trenches (Bykovka, Sokovka, Vyazniki Iand Metallist in the Vyazniki region) as well as natural outcrops onthe valley slopes (Balymotikha in the Vyazniki region; Zhukov Ravine,

ur in red and greenish gray colored claystone intercalations. CO marks the horizons withFormation (Vokhmian Regional Stage; Early Triassic). Scale bars: A, 20 cm; B, 10 cm; C

eferred to the web version of this article.)

Table 1Studied localities with occurrences of conchostracans of the Vokhmian Regional Stage(Early Triassic) in the Moscow syncline. The section numbers for Zhukov Ravine andArefino Ravine correspond to the profile documentations (e.g., Golubev et al., 2012a,b).

Name of section Coordinates Occurring conchostracan taxa

Zhukov Ravine(section no. 1236)

56°10′42.3″ N,42°38′27.5″ E

Rossolimnadiopsis sp.

Zhukov Ravine(section no. 1029)

56°10′46.0″ N,42°38′23.2″ E

Palaeolimnadiopsis vilujensis

Arefino Ravine(section no. 1225)

56°10′37.9″ N,42°37′36.1″ E

Cornia germari, Magniestheriamangaliensis, Palaeolimnadiopsisvilujensis

Staroye Slukino 56°11′8.3″ N,42°38′23.4″ E

Cornia germari

Fedurniki sand pit 56°13′9.6″ N,42°15′2.7″ E

Magniestheria mangaliensis,Euestheria gutta


Arefino Ravine and Staroye Slukino in the Gorokhovets region). Thespecimens described in this paper were collected from the Early Triassicintervals (Table 1).

For the present study 150 conchostracan specimens have beendrawn and photographed using a Zeiss Discovery V8 stereomicroscopeequipped with an automatic camera stack-image system. Themorphol-ogies of conchostracan carapaces were described using the terminologyof Goretzki (2003), which is mainly based on quantitative (e.g., size,relative length, numbers of growth lines, shape, position of the umbo)and semi-quantitative (e.g., intensities of the curvatures at the marginsof a valve) measurements of the valves. The taxonomic analysis wasperformed by both interpretation of Russian conchostracan literature(e.g., Lutkevitch, 1937; Novozhilov, 1946, 1970) and comparisons withrespective data from the Lower Buntsandstein Subgroup (Calvördeand Bernburg Formations; Early Triassic) in the Germanic Basin(e.g., Kozur, 1982; Kozur and Seidel, 1983a; Kozur and Weems, 2010,2011; Scholze, 2011). However, we are well aware of the fact that theconchostracan taxonomy of Novozhilov should be handledwith cautiondue to large numbers of synonyms (Goretzki, 2003; Kozur and Seidel,1983a; Tasch, 1958). The conchostracan material of this study is storedin the palaeontological collection of the Geological Institute, TUBergakademie Freiberg (abbreviated as FG, followed by the respectivespecimen number) and in the collection of the NaturhistorischesMuseum Schleusingen (abbreviated as MT).

5. Systematic paleontology

Class Branchiopoda Latreille, 1817Order Spinicaudata Linder, 1945Family Vertexiidae Kobayashi, 1954Genus Cornia Lutkevitch, 1937Type species. Cornia papillaria Lutkevitch, 1937Remarks. Following the emended diagnosis of Kozur and Seidel

(1983a) the genus Cornia has a long, straight dorsal margin and aspine at the umbo.

Cornia germari (Beyrich, 1857) emend. Kozur, 1982Fig. 8A–D, Fig. 9A–BMaterial. FG 660/2, FG 660/3/1, FG 660/3/2 from Arefino Ravine, FG

660/4 from Staroye Slukino; Vokhma Formation, Vokhmian RegionalStage.

Description. Carapace medium-sized (2.5–2.7 mm) and oval inshape; dorsalmargin straight and long; position of theumbo submedianand inframarginal; larval valve small; growth lines 10–16, wide-spaced;anterior and posterior margins sharply curved to very sharply curved;position of themaximal curvature of the anteriormarginmedial–dorsal,at the posterior margin medial to medial–ventral, and at the ventralmargin medial–anterior to medial–posterior.

Occurrence. Vokhma Formation in the Arefino Ravine (section no.1225, bed 4) and in the Staroye Slukino locality; Bernburg Formation,

Lower Buntsandstein of the Germanic Basin (Kozur and Seidel, 1983a);Arács Marl Formation, Werfen Group in Hungary (Kozur and Mock,1993); Krasnobakovsk Member, Rybinskian Horizon, Vetlugian Seriesof the Russian Platform (Kozur, 1998); beds above the Siberian trapbasalts in the Timan–Petchora Basin (Kozur, 1998); late Induan inGreenland (Kozur, 1998).

Remarks. A detailed synonymy list for C. germari was provided byKozur and Seidel (1983a). A high variability in deformation of bothspine and umbo led Kozur (1983) to distinguish between Cornia-,Echinestheria-/Wetlugites-, Sedovia-/Palaeolimnadia- and Vertexia-typesof preservation. In the present study all these preservation types areregarded asCornia, because the primary position of the spines ismarkedby concentric sedimentary fillings of their base at the external surface ofthe umbo. Even if the umbonal spine is not completely preserved, itscast is clearly recognizable by use of a simple lens. This enables bothtaxonomic determination and a first biostratigraphic interpretation inthe field.

Family Euestheriidae Defretin-Lefranc, 1965Genus Euestheria Depéret and Mazeran, 1912Type species. Posidonia minuta Von Zieten, 1833Remarks. Euestheria can be regarded as a ‘bag-genus’ (e.g., Vannier

et al., 2003), because thus far it lacks adequate definition. Followingthe emended diagnosis of Kozur and Seidel (1983a) this genus showsa valve with convex shape and a pronounced umbo area. According toKozur and Seidel (1983a) the morphology and shape of Euestheriadepend strongly on dimorphisms and preservational variability.

Euestheria gutta (Lutkevitch, 1937)Fig. 9C–D, Fig. 10A–BMaterial. FG 660/5, FG 660/6, FG 660/7 from Fedurniki sand pit;

Vokhma Formation, Vokhmian Regional Stage.Description. Carapace small to medium-sized (2.2–2.8mm) and oval

in shape; dorsal margin straight and very short; position of the umboanterior and inframarginal; larval valve small to large; growth lines13–17, close- to wide-spaced; anterior and posterior margins verysharply curved; position of the maximal curvature of the anteriormargin medial–dorsal, at the posterior margin medial–ventral, and atthe ventral margin median–posterior.

Occurrence. VokhmaFormation in the Fedurniki sand pit (uppermost3mof the section); Calvörde Formation and Bernburg Formation, LowerBuntsandstein of the Germanic Basin (Kozur and Seidel, 1983a);Rybinskian horizon (Vetlugian Series, Early Triassic) on the Russianplatform (Goretzki, 2003; Lutkevitch, 1937); Kayitou Formation inSouth China (Chu et al., 2013).

Remarks. A detailed synonymy list for E. gutta was given by Kozurand Seidel (1983a). A pronounced sexual dimorphism of E. gutta wasmentioned in former studies from the Lower Buntsandstein in theGermanic Basin by Kozur and Seidel (1983a). However, it is knownfrom ongoing investigations (FS) that because of high intraspecificvariability many more of the described species will be synonymizedwith E. gutta. Kozur and Seidel (1983a) distinguish between the twosubspecies E. gutta gutta (Lutkevitch, 1937) and E. gutta oertlii Kozur,1980. In the Germanic Basin E. gutta gutta is most common in theCalvörde Formation but rare in the Bernburg Formation, while theopposite is the case for E. gutta oertlii. The specimens from the Fedurnikisection resemble E. gutta gutta, because the number of growth lines isless than 20 and aweakening of growth line preservation is characteris-tic of the umbonal area.

Superfamily Cyzicacea Stebbing, 1910Family Bairdestheriidae Novozhilov, 1954Genus Magniestheria Kozur, 1982Type species. Magniestheria truempy Kozur and Seidel, 1983Remarks. Magniestheria was defined by Kozur (1982) as a subgenus

of Liograpta Novozhilov, 1954 and classified within the familyBairdestheriidae Novozhilov, 1954 in the superfamily CyzicaceaStebbing, 1910. Later it was raised to the rank of genus (e.g., Kozurand Weems, 2010), which is followed here.

Fig. 8. Cornia germari (Beyrich, 1857), Vokhma Formation, Early Triassic (Vokhmian Regional Stage), sections at Arefino Ravine and Staroye Slukino (Vladimir region, Central Russia). A,lateral view of a left valvewith remnants of shell substance; former position of a spine on the umbo is indicated by its concentric sediment filled base; ArefinoRavine (section 1225, bed 4);FG 660/2. B, lateral view of a right valve with remnants of shell substance; the concentric base of the umbonal spine is shifted towards the edge of dorsal and anterior margins due to de-formation; Arefino Ravine (section 1225); FG 660/3/1. C, lateral view of a right valve with remnants of shell substance; concentric base of the spine is located in the center of the umbo;Arefino Ravine (section 1225); FG 660/3/2. D, lateral view of a left valve preserved as an internal cast; Staroye Slukino; FG 660/4.


Magniestheria mangaliensis (Jones, 1862)Fig. 10C–D, Fig. 11A–D, Fig. 12A–DMaterial. FG 660/8, FG 660/9, FG 660/10, FG 660/11, FG 660/13, FG

660/1/2, FG 660/14 from Arefino Ravine, FG 660/12 from Fedurnikisand pit; Vokhma Formation, Vokhmian Regional Stage.

Description. The valves show variations in height/length-ratio, whichlead us to distinguish between a slender and a stout morphotype.

Stout morphotype: Carapace medium-sized to large (3.3–4.2 mm)and oval to round in shape; dorsal margin straight and short; positionof the umbo submedian and inframarginal; larval valve very small tosmall; growth lines 24–28, close- to wide-spaced; anterior margin

sharply curved to very sharply curved; posterior margin very sharplycurved; position of maximal curvature of the anterior margin medial–dorsal to medial, at the posterior margin medial, and at the ventralmargin medial-posterior.

Slender morphotype: Carapace very large to extremely large(4.5–8.7 mm) and oval in shape; dorsal margin straight and long; posi-tion of the umbo submedian and inframarginal; larval valve very small;growth lines 10–24, wide- to very wide-spaced; anterior and posteriormargins sharply curved to very sharply curved; medial position ofmaximal curvatures of anterior and posterior margins, and at theventral margin medial-posterior.

Fig. 9. A–B, Cornia germari (Beyrich, 1857), Lower Buntsandstein Subgroup, Early Triassic (Induan), sections at Sangerhausen and Beesenlaublingen (Saxony-Anhalt, Germany). A, lateralview of a right valve preserved as an internal cast; former position of the spine at the umbo is clearly visible by its sediment filled base; temporary outcrop during A38/A71 highway con-struction, 3 km southeast of Sangerhausen; Bernburg Formation (0.90m above oolite horizon Jota); FG 618/18. B, lateral view of a right valve preserved as an internal cast; former positionof the spine at the umbo is clearly visible by its sediment filled base; Beesenlaublingen quarry, 1 km southeast of Zweihausen; Bernburg Formation (25 m above oolite horizon Zeta); FG618/15. C–D, Euestheria gutta (Lutkevitch, 1937), Vokhma Formation, Early Triassic (Vokhmian Regional Stage), section at Fedurniki (Vladimir region, Central Russia). C, lateral view of aright valve in three-dimensional preservation of an internal cast; Fedurniki sand pit (uppermost 3 m of the section); FG 660/5. D, right lateral view of a carapace in three-dimensionalpreservation of an internal cast; Fedurniki sand pit (uppermost 3 m of the section); FG 660/6.


Occurrence. Vokhma Formation in the Arefino Ravine (section no.1225, bed 4, slender morphotype; bed 8, stout morphotype) andFedurniki sand pit (lower conchostracan horizon); uppermost BernburgFormation and Volpriehausen Formation, Lower toMiddle Buntsandstein(Kozur and Seidel, 1983a); Arács Marl Formation, Werfen Group, inHungary (Kozur and Mock, 1993); Mangali Formation, Panchet Forma-tion, and Kamthi Formation in India (Gosh, 2011; Jones, 1862; Tasch,1987).

Remarks. This specieswasfirst described as Estheriamangaliensis Jones(1862) from Mangali, Central India. Furthermore, it also became knownas Liograpta (Magniestheria) mangaliensis by Kozur and Seidel (1983a)and M. mangaliensis by Kozur and Weems (2010). The high variabilityof this species was described in detail by Kozur and Seidel (1983a), whoalso distinguished between a stout and a slender morphotype. The vari-ability of this species is interpreted as pronounced sexual dimorphismand a result of ecological factors (Kozur and Seidel, 1983a).

Fig. 10. A–B, Euestheria gutta (Lutkevitch, 1937), sections at Fedurniki (Vladimir region, Central Russia) and Bücheloh (Thuringia, Germany), Early Triassic. A, left lateral view of a carapacein three-dimensional preservation of an internal cast; Fedurniki sand pit (uppermost 3mof the section); Vokhma Formation, Early Triassic (Vokhmian Regional Stage); FG 660/7. B, lateralview of a left valve preserved three-dimensionally as internal cast; temporary outcrop during B88 road construction, 1.5 km southwest of Bücheloh; lower part of the upper BernburgFormation (Lower Buntsandstein Subgroup), Early Triassic (Induan); FG 660/24. C–D, slender morphotype ofMagniestheria mangaliensis (Jones, 1862), Vokhma Formation, Early Triassic(Vokhmian Regional Stage), section at ArefinoRavine (Vladimir region, Central Russia). C, lateral view of a left valvewith remnants of shell substance; apparently large ‘larval shell’, due toerasure of growth lines at the umbo; Arefino Ravine (section 1225, bed 4); FG 660/8. D, lateral view of a right valve; transition between preservation as internal cast and cast with shellsubstance; Arefino Ravine (section 1225, bed 4); FG 660/9.


Superfamily Palaeolimnadiopseoidea Defretin-Lefranc, 1965 (nom.transl. Kobayashi, 1973)

Family Palaeolimnadiopseidae Defretin-Lefranc, 1965 (nom. transl.Kobayashi, 1973)

Genus Palaeolimnadiopsis Raymond, 1946Type species. Palaeolimnadiopsis carpenteri Raymond, 1946Remarks. Palaeolimnadiopsid conchostracans are known from theDe-

vonian to Cretaceous (e.g., Shen, 1985; Gallego, 2005: Table 1). The mostprominent morphological character of Palaeolimnadiopsis is a concave

recurvature of the posterior margin directly below the dorsal margin.However, preserved as imprints or in combination with sediment defor-mation this recurvature generally becomes more indistinct towards theoutline of the valve. The type species P. carpenteri from the late EarlyPermian (Leonardian) of Oklahoma is extremely large (42mm in length;Raymond, 1946). The convex recurvature of the upper posterior marginand the large to extremely large size are the characteristics of that taxon.

Palaeolimnadiopsis vilujensis Varentsov, 1955Fig. 13A–D, Fig. 14A–B

Fig. 11. Slender morphotype of Magniestheria mangaliensis (Jones, 1862), sections at Arefino Ravine and Fedurniki (Vladimir region, Central Russia) and Baalberge (Saxony-Anhalt,Germany), Early Triassic. A, lateral viewof a right valvewith transition of shell substance and internal cast preservation; brittle deformation at posterior and dorsalmargins; ArefinoRavine(section 1225, bed 4); Vokhma Formation; Vokhmian Regional Stage; FG 660/10. B, lateral view of a left valve with preservation of shell substance; weakening of growth line preservationat the umbo; Arefino Ravine (section 1225, bed 4); Vokhma Formation; Vokhmian Regional Stage; FG 660/11. C, lateral view of a right valve with transition of shell substance and internalcast preservation; Fedurniki sand pit (lower conchostracan horizon); Vokhma Formation; Vokhmian Regional Stage; FG 660/12. D, lateral view of a left valve preserved as a compactedinternal cast; Baalberge quarry, 1 km northwest of Baalberge; Volpriehausen Formation (3 m above Volpriehausen-sandstone), Middle Buntsandstein Subgroup; late Early Olenekian;MT1304-2.


Material. FG 660/15 from Arefino Ravine, FG 660/16, FG 660/17, FG660/18 from Zhukov Ravine; Vokhma Formation, Vokhmian RegionalStage.

Description. Carapace very large to extremely large (4.7–6.5 mm)and oval in shape; dorsal margin straight and long; position of theumbo submedian and inframarginal; larval valve very small to large;growth lines 11–19, very wide-spaced; each growth line consists oftwo separated lines; anterior and posterior margins sharply curved;positions of maximal curvatures of the anterior and posterior marginsmedial–dorsal, and at the ventral margin medial to medial–posterior.

Occurrences. Vokhma Formation in the Arefino Ravine (section no.1225, bed 8) and Zhukov Ravine (section no. 1029, bed 10); upperFulda Formation, Upper Zechstein, and lower Calvörde Formation,Lower Buntsandstein, in Germany; Permian to Triassic beds in Yakutia(Varentsov, 1955).

Remarks. In theArefinoRavine (section no. 1225) and Zhukov Ravine(section no. 1029) all specimens of P. vilujensis show mixtures of shellsubstance and sediment cast preservation. It is important to mentionthat in both kinds of preservation a convex bulge on each growth lineis distinctly bounded by two fine lines (Fig. 15). Such a set of two fine

Fig. 12. Stoutmorphotype ofMagniestheriamangaliensis (Jones, 1862), sections at ArefinoRavine (Vladimir region, Central Russia) andBaalberge (Saxony-Anhalt, Germany), Early Triassic.A, lateral view of a left valve with transition of shell substance and internal cast preservation; in the umbonal area prominent concentric ribs are developed on growth bands; Arefino Ra-vine (section 1225, bed 8); Vokhma Formation;Vokhmian Regional Stage; FG 660/13. B, lateral viewof a left valvewith transition of shell substance and internal cast preservation, showingindistinct outline at the edge of dorsal and posteriormargins; ArefinoRavine (section 1225, bed 8); Vokhma Formation; Vokhmian Regional Stage; FG 660/1/2. C, lateral viewof a left valvewith preservation of shell substance, but flattened by compaction;ArefinoRavine (section 1225, bed 8); Vokhma Formation; Vokhmian Regional Stage; FG660/14. D, lateral viewof a rightvalve preserved as internal cast; in the central part concentric ribs are developed; Baalberge quarry, 1 km northwest of Baalberge; Volpriehausen Formation (3 m above Volpriehausen-sandstone), Middle Buntsandstein Subgroup; late Early Olenekian; MT1304-6.


lines on the growth lines of Permian and Triassic palaeolimnadiopsidconchostracans is also known from Koreolimnadiopsis tokioi Ozaki,1970 and Palaeolimnadiopsis bassi Webb, 1978.

Genus Rossolimnadiopsis Novozhilov, 1958Type species. R. marlierei Novozhilov, 1958Remarks. The type locality of this taxon was described by

Novozhilov (1958) as “city Vyazniki, in the light, yellowish-grayschists”. Unfortunately, the holotype defined by Novozhilov (1958)

is missing (Goretzki, 2003). Furthermore, according to Goretzki (2003)the figures of Novozhilov (1958) are not completely reproducible(inaccurate drawings, photos retouched). Thus, the full taxonomicrange of this species remains problematical. However, in someimportant morphological aspects (e.g., round shape, concave growthlines; see below) our newly collected material from the ZhukovRavine strongly resembles the drawing of R. marlierei by Novozhilov(1958: Fig. 3).

Fig. 13. Palaeolimnadiopsis vilujensis Varentsov, 1955, Vokhma Formation, Early Triassic (Vokhmian Regional Stage), section at Arefino Ravine and Zhukov Ravine (Vladimir region, CentralRussia). A, lateral view of a right valve with transition of shell substance and internal cast preservation; plastic deformation in the center; typical concave recurvation of the posteriormargin below the dorsal margin; Arefino Ravine (section 1225, bed 8); FG 660/15. B, lateral view of a left valve with transition of shell substance and internal cast preservation; radialstructures caused by plastic deformation; growth lines are finely paired; Zhukov Ravine (section 1029, bed 10); FG 660/16. C, lateral view of a right valve with transition of shell substanceand internal cast preservation; indistinct outline towards the posterior margin; growth lines are finely paired; Zhukov Ravine (section 1029, bed 10); FG 660/17. D, lateral view of a leftvalve preserved as an imprint on the bedding plane; outer margins of the valve are indistinct; growth lines are finely paired; Zhukov Ravine (section 1029, bed 10); FG 660/18.


Rossolimnadiopsis sp.Fig. 14CMaterial. FG 660/20, FG 660/21 from Zhukov Ravine, Vokhma

Formation; Vokhmian Regional Stage.Description. Carapace extremely large (6.6 mm) and round in

shape; dorsal margin long and concave; position of the umbo anteri-or, inframarginal; larval valve very small; growth lines 33, wide-spaced; anterior margin very sharply curved, posterior marginsharply curved; positions of maximal curvatures of the anterior

and posterior margins medial–dorsal, and at the ventral marginmedial–posterior.

Occurrences. Vokhma Formation in the Zhukov Ravine (section no.1236, bed 3).

Remarks. The most prominent morphological character isthe round shape of the valve. The fact that Rossolimnadiopsisbelongs to the palaeolimnadiopsids is supported by the combina-tion of the slightly concave recurvation of growth lines below thedorsal margin and the extremely large size of the carapace. This

Fig. 14. A–B, Palaeolimnadiopsis vilujensis Varentsov, 1955, uppermost Zechstein and basal Lower Buntsandstein, section at Caaschwitz quarry (Thuringia, Germany), transitional LatePermian (latest Changhsingian) to Early Triassic (earliest Induan). A, lateral view of a right valve preserved as an internal cast; typical concave recurvature of growth lines at the posteriormargin below the dorsal margin; radial structures caused by plastic deformation during compaction; weakening of growth line preservation at the umbo; active Caaschwitz quarry;Calvörde Formation (5.5 m above base of cycle 1), Lower Buntsandstein Subgroup; FG 618/7b. B, lateral view of a right valve preserved as imprint on the bedding pane; typical concaverecurvature of growth lines at the posteriormargin below the dorsal margin; active Caaschwitz quarry; Fulda Formation (10mbelowbase of Calvörde Formation), upper part of Zechsteincycle z7; FG 660/22. C, lateral view of a right valve of Rossolimnadiopsis sp. with remnants of shell substance; concave bending of the dorsal margin is characteristic of the genusRossolimnadiopsis Novozhilov, 1958; Vokhma Formation, Early Triassic (Vokhmian Regional Stage), section 1236 at Zhukov Ravine, Vladimir region, Central Russia; FG 660/20. D,palaeolimnadiopsid specimen similar to Rossolimnadiopsis sp., lateral viewof a left valve preserved as an imprint on the beddingpane; concentric ribs in the central part of the valve; typicalconcave recurvature of growth lines at the posterior margin below the dorsal margin; indistinct outline towards the posterior margin; active Caaschwitz quarry (Thuringia, Germany);Fulda Formation (10 m below base of Calvörde Formation), upper part of Zechstein cycle z7; transitional Late Permian (latest Changhsingian) to Early Triassic (earliest Induan); FG660/23.


recurvation is best visible below the central part of the dorsalmargin.

So far, this form is represented by one individual (part and counter-part of the right valve). The above described form is larger (6.6 mm)than R. marlierei (3.2 mm); therefore it is classified to the genus level

only. Since R. marlierei and Rossolimnadiopsis sp. seem to be very rareand the available material therefore limited, the question of whetherthe concave bending of the dorsal margin was caused by deformation re-mains unsolved. However, the similarity of concave bending between ournew samples and the type specimen illustrated by Novozhilov (1958)

Fig. 15. Shell of Palaeolimnadiopsis vilujensis with preservation of bulges on the growthlines, each bounded by two fine lines (marked by arrows); FG 660/17; Zhukov Ravine(section no. 1029, bed 10); Early Triassic (Vokhmian Regional Stage).

Fig. 16. Magniestheria mangaliensis (stout morphotype) associated with ostracods(arrows); FG 660/1/1; Arefino Ravine (section 1225, bed 8); Early Triassic, VokhmianRegional Stage.


suggest that this is a primary morphological feature of Rossolimnadiopsis.Morematerial is necessary for accurate determination at the species level.

6. Discussion

6.1. Taphonomy

Recent conchostracans preferentially inhabit small inland waterbodies (cf. Tasch, 1969; Webb, 1979). They are commonly found inlow energy shallow waters such as temporary ponds and lakes. Singlespecimens from the sections at the Fedurniki sand pit and ArefinoRavine were autochthonous buried in life position. Autochthonousburial can be assumed for conchostracans from the sections at ZhukovRavine and Staroye Slukino as well, because damage to the valvescaused by transport is not significant. This interpretation is supportedby the lithology. The respective conchostracan-bearing beds consist ofhorizontally laminated claystones to siltstones deposited from suspen-sion under low energy conditions.

In the Early Triassic section intervals at Zhukov Ravine, ArefinoRavine and Staroye Slukino the conchostracans are preserved withwhite shells. This shell substance either covers the whole surface of avalve or consists of fragments with transitions into imprint preserva-tion. Because recent conchostracan shells are transparent to translucentor of light amber, brown to brownish-red, or yellow color (Tasch, 1969),it is assumed that thewhite color of the shell substancewas caused by adiagenetic overprint of the original chitinous substance.

An exception is the three-dimensional preservation of E. guttawithout any shell substance in the upper Fedurniki sand pit. There,they occur monospecifically in intercalations of red claystone andsiltstone within fluvial sandstones. Obviously, the internal sedimentaryfilling of the valves prevented intensive deformation by compactionand post-sedimentary diagenetic processes completely dissolved thechitinous shells.

6.2. Association of conchostracans and ostracods

The ostracods from the Late Permian intervals of the Moscow syn-cline were analyzed by Kukhtinov et al. (2008), but the Early Triassicmaterial has not yet been studied in detail. Here, we will focus on thepaleoecology of Early Triassic ostracods, because they are frequentlyassociated with conchostracans in all sections studied here with theexception of the Fedurniki sand pit. Darwinulid ostracods in the ZhukovRavine occur on the same bedding plane with Rossolimnadiopsis sp.

(section no. 1236, bed 3) and P. vilujensis (section no. 1029, bed 10).In the Arefino Ravine (section no. 1225) co-occurrences of darwinulidsare restricted to bed 8, where they are associated with the stoutmorphotype of M. mangaliensis (Fig. 16).

Early Triassic ostracods are mainly reported from marine environ-ments (e.g., Crasquin-Soleau and Kershaw, 2005; Forel and Crasquin,2011; Forel et al., 2013). Nonmarine ostracod assemblages have beenused by Pang (1993) and Pang and Jin (2004) for placement of thePTB in continental sections in China, while from the Germanic Basinostracods in the Early Triassic sections were only rarely mentioned(e.g., Kozur and Seidel, 1983b; Scholze, 2011). More detailed ostracod-biofacies analyses would require taxonomic determinations, sincesingle taxa might have been constrained to specific environmentalconditions. Comparative studies of recent nonmarine species fromIllinois (USA) by Hoff (1942) showed that the habitats of ostracodscan be grouped into temporary still water (e.g., ponds, pool, ditches,small water-filled depressions), permanent still water (e.g., lakes,swamps, lake-like backwaters of large rivers), temporary runningwater (e.g., pools left in dried stream beds), and permanent streamsof all sizes. Hoff (1942) demonstrated a tight relationship betweenostracodmorphology and the velocity of thewater current, since certainspecies are confined almost without exception to water in whichthere is no current. Species living in running water seem to be charac-terized by a rather large shell, rectangular, compressed, and sometimesornamented by furrows or protuberances (Hoff, 1942). In contrast, ac-tive swimmers adapted to quiet water conditions show well developedswimming setae, often tumid shells, and have little ability to maintainthemselves against strong currents (Hoff, 1942). All the ostracodsfrom the Early Triassic intervals of the sections studied here arepreserved as smooth and thin, prominent white, calcitic shells of up to0.6 mm length. The lack of furrows or protuberances might indicatequite water conditions in the habitat.

6.3. Biostratigraphy

In the following, Permian and Triassic are used only in regard to theregional stratigraphic schemes for the Germanic Basin and the Moscowsyncline. In both areas the PTB is determined by conventions of the re-spective national stratigraphic commissions. In the Germanic Basin thebeginning of the Triassic is traditionally placed at the lithostratigraphicbase of the Buntsandstein in the sense of Alberti (1834), which contin-uously overlay the marine to sabkha deposits of the Zechstein, whichare regarded as of Permian age. Such a placement of the PTB at the

Fig. 17. Vertebra fragments of Tupilakosaurus sp. from Zhukov Ravine (A), Arefino Ravine (B), Fedurniki sand pit (C), and Staroye Slukino (D) in the Tupilakosaurus wetlugensis Zoneindicating the Early Triassic age (Vokhmian Regional Stage) of the studied intervals.


base of the Buntsandstein is useful for applied geology (e.g., geologicmapping) and accepted by regional geological surveys (LBEG, 2014). ALate Permian Early Wuchiapingian biostratigraphic age is only provenfor the start of the Zechstein transgression by the occurrence ofMesogondolella britannica in the Kupferschiefer, which marks the baseof the first Zechstein cycle (Werra Formation) (Legler and Schneider,2008). The position of the PTB after Bachmann and Kozur (2004),which should be situated at the beginning of the second cycle of theCalvörde Formation in the Lower Buntsandstein Subgroup based onconchostracans, is in revision now (Scholze, 2014; Scholze et al., 2014).In the Moscow syncline the base of the Triassic is biostratigraphicallydeterminedby the disappearance of almost all Late Permian taxa of plantsand animals and the appearance of a very poor Tupilakosaurus fauna, as atypical post-crisis fauna (Ochev and Shishkin, 1998) as discussed below.

6.3.1. TupilakosaurusThe determination of the PTB by regional comparisons of lithology,

magnetostratigraphy and biostratigraphy in the nonmarine profilesaround Vyazniki and Gorokhovets has been discussed in detail by previ-ous workers (e.g., Golubev and Sennikov, 2010; Golubev et al., 2012a,b;Kukhtinov et al., 2008; Newell et al., 2010; Sennikov and Golubev, 2005,2006, 2010a,b, 2012, 2013a,b). According to the tetrapod biozonationof Golubev et al. (2012a, 2012b) the earliest Triassic intervals of thestudied sections correspond to the T. wetlugensis Zone. In the respectiveintervals of Zhukov Ravine, Fedurniki sand pit, Arefino Ravine, andStaroye Slukino this zone can be traced by isolated fragments ofTupilakosaurus sp. during previous studies (e.g., Sennikov and Golubev,2012) and recent field campaigns (Fig. 17). Furthermore, Tupilakosaurushave been reported in association with Early Triassic (Induan) ammo-nites in Greenland, which links the respective zone to the Induan ofthe global marine standard scale (cf. Lozovsky, 1997; Lucas, 2010;Shishkin et al., 2000). Thus, the co-occurrences of Tupilakosaurus andconchostracans in the studied sections support the Early Triassic age ofthese intervals.

The family Tupilakosauridaewas interpreted by Benton et al. (2004)as a disaster taxon appearing immediately after the end-Permian crisis.According to Lucas (2010) the amphibian Tupilakosaurus is one ofthe index taxa for the Lootsbergian Land Vertebrate Faunachrone,which correlates to an interval of latest Changhsingian to possibly earli-est Olenekian age. However, fragments of a tupilakosaurid vertebralcolumn were reported by Werneburg et al. (2007) from the (?)LatePermian La Lieude Formation of the Lodève basin in Southern France.This may indicate that members of the family Tupilakosauridae appearas early as in the later Permian. In any case, on the East European plat-form and in the Cis-Uralian foredeep Tupilakosaurus was never foundtogetherwith Late Permian faunal elements, instead, itsfirst appearanceis directly above the PTB where it forms widespread mass occurrences.Therefore, T. wetlugensis could be regarded as a biostratigraphic indica-tor for the Early Triassic (Induan).

6.3.2. C. germari and E. guttaThe occurrence of C. germari (Fig. 8A–D) in the sections at Arefino

Ravine and Staroye Slukino can be used as a biostratigraphic indicatorfor the Early Triassic Induan age, because the spined conchostracangenera Cornia, Vertexia, and Molinestheria are unknown in the LatePermian but common in the Early Triassic of Germany (e.g., Kozur,1979, 1983; Kozur and Seidel, 1983a; Martens, 1982), Hungary (Kozurand Mock, 1993), Russia (e.g., Chunikhin, 2009; Kozur et al., 1983),China (Liu, 1995), India (Gosh, 2012) and South America (Tassi et al.,2013). Referring to the present conchostracan biozonation (Kozur andWeems, 2010) the first occurrences of spined conchostracans such asVertexia tauricornis, Molinestheria seideli, and C. germari is situatedwithin the M. seideli Zone of Kozur and Weems (2010), which belongsto the Induan (Early Triassic; lower Gandarian in Kozur and Weems,2010). The youngest occurrence of these spined taxa is representedby the last occurrence of C. germari in the C. germari–Magniestheriasubcircularis Zone of Kozur and Weems (2010) in the late Induan.

Themass occurrences of E. gutta in the Fedurniki sand pit might alsobe indicative of an Early Triassic age, because in the Germanic Basinmass occurrences of this species are known from the Calvörde andBernburg Formations (both Lower Buntsandstein Subgroup) in theInduan. Thus far, however, the real lower stratigraphic range of thisspecies seems to be less certainly known, due to the poor preservationpotential of the haloturbated sabkha fine clastics in the uppermostZechstein Group (Fulda Formation; Late Permian) of the GermanicBasin.

The conchostracans analyzed here bear remarkable resemblance tothe fauna of the Early Triassic Lower Buntsandstein Subgroup in theGermanic Basin. Reinvestigations of classical and new sections ofthe Lower Buntsandstein in central Germany (Thuringia and Saxony-Anhalt) confirmed a fauna consisting of C. germari (Fig. 9A–B), E. gutta(Fig. 10B), and P. vilujensis (Fig. 14A–B). Regardless ofwhether the strat-igraphic position of the PTB in the Germanic Basin is used in the senseof Menning et al. (2005) and Menning and Käding (2013) or afterBachmann and Kozur (2004) and Kozur andWeems (2010), respective-ly, or those discussed by Scholze in Schneider et al. (2014: p. 77–79) itwould attribute the stratigraphic range of both C. germari and E. guttato the Early Triassic in Central Russia and Germany.

6.3.3. M. mangaliensisM. mangaliensis formsmass occurrences in the Arefino Ravine and is

associated there with C. germari and P. vilujensis. Mass occurrencesof M. mangaliensis in Germany are restricted to a monospecific faunain the Volpriehausen Formation of the Middle Buntsandstein Subgroup(e.g., Kozur and Seidel, 1983a; Kozur and Weems, 2010). Interestingly,this mass occurrence in the Germanic Basin (Baalberge quarry,Saxony-Anhalt, Germany) belongs to an interval of the VolpriehausenFormation from which a marine influence is assumed because of the


occurrence of prasinophycean algae and acritarchs (Roman, 2004).Kozur (1982) assumed that salinity fluctuations in this brackish intervalof the Volpriehausen Formation nearly reached themaximum tolerancelevel forM. mangaliensis, thus resulting in high intraspecific variability.In combination with an assumed pronounced sexual dimorphism(Kozur and Seidel, 1983a), this makesM. mangaliensis a morphological-ly widely variable species. The latter is supported by the stout and slen-dermorphotypes of this species described here that occur in the ArefinoRavine section as well as in the Baalberge section (Fig. 11D; Fig. 12D).

The type material ofM. mangaliensis (=E. mangaliensis Jones, 1862)came from the Early Triassic Panchet Formation of India (Goretzki,2003),which correspondswell in its tetrapod assemblage (LootsbergianLandVertebrate Faunachrone; Lucas, 1998, 2010) to an Induan age (Dasand Gupta, 2012). This species was wrongly used by Kozur andWeems(2010) as an index species for the definition of their M. mangaliensisZone, which should be of late Early Olenekian age. Additionally, this isin conflict with the co-occurrence of this species with C. germari,which should be, after Kozur and Weems (2010), an index species forthe Induan. In contrast to the Arefino Ravine section, co-occurrencesof M. mangaliensis and C. germari are not known so far in the GermanicBasin. Despite this, the first occurrence of M. mangaliensis is definitelysituated just above the PTB in the early Induan.

6.3.4. PalaeolimnadiopsisThe biostratigraphic relevance of P. vilujensis in the Zhukov Ravine

and Arefino Ravine sections remains uncertain and requires furtherinvestigation. The holotype of P. vilujensis came fromPermian to Triassicdeposits in Yakutia (Varentsov, 1955). In the nonmarine Late Permian toEarly Triassic transitional section of the Caaschwitz quarry in Thuringia,rare finds of P. vilujensis (Fig. 14A–B) came from both the upper FuldaFormation (uppermost Zechstein group) and the lower CalvördeFormation (lowermost Lower Buntsandstein Subgroup). Therefore, arange from the Late Permian to the Early Triassic is most probable.

6.3.5. RossolimnadiopsisAccording to Novozhilov (1958) R. marlierei should come from the

Late Permian in an outcrop near the city of Vyazniki. However, our singlespecimen of Rossolimnadiopsis sp. from the Zhukov Ravine is of Early Tri-assic age. Consequently, a Late Permian to Early Triassic range has to beassumed in contrast to Novozhilov (1958). Although palaeolimnadiopsidconchostracans with a round shape like Rossolimnadiopsis sp. are rare inthe Zhukov Ravine (section 1236), a single specimen of that type wasrecently collected in the Fulda Formation of the Caaschwitz section(Fig. 14D).

7. Conclusion

The regional Permian–Triassic boundary in the continental profilesof the East European platform and the Cis-Urals is marked by a suddenextinction event of terrestrial biota and immediately after that bythe widespread and common occurrence of the aquatic tetrapodTupilakosaurus. In the Moscow syncline the well-documented andwell-investigated profiles of Zhukov Ravine, Arefino Ravine, StaroyeSlukino, and Fedurniki sand pit in the vicinity of the towns of Vyaznikiand Gorokhovets have been sampled for conchostracans fromabout 40 m below the PTB up to about 30 m above the PTB. Belowthe PTB in the Zhukovian Regional Stage only the typical Permianpseudestheriid fauna was detected. In the earliest Triassic T. wetlugensisZone of the Vokhmian Regional Stage the conchostracan fauna consistsof C. germari, E. gutta,M. mangaliensis, P. vilujensis, and Rossolimnadiopsissp. This association appears only decimeters above the base of theT. wetlugensis Zone. A comparable fauna including C. germari, E. gutta,and P. vilujensis is known from the Calvörde and Bernburg Formationsof the Lower Buntsandstein Subgroup in the Germanic Basin. Therefore,this conchostracan association could be regarded to be of Early Triassic

age in the continental settings of the East European platform and theGermanic Basin.

Acknowledgment

F. Scholze and J.W. Schneider thank the German Research Founda-tion (grant number SCHN408/22-1) for funding of ongoing fieldcampaigns. The studies of A.G. Sennikov andV.K. Golubevwere partiallysupported by the Russian Foundation for Basic Research (projectnumbers 13-05-00274, 13-05-00592, 14-04-00185, 14-04-01128,14-05-93964, 13-05-00642), by the Program of Basic Research of thePresidium of the Russian Academy of Sciences No. 30 “The evolution ofthe organic world and planetary processes”, and by the subsidy of theRussian Government to support the Program of Competitive Growth ofKazan Federal University among World's Leading Academic Centers.The study of G. Niedźwiedzki was supported by grants from the PolishMinistry of Science and Higher Education (no. 7986/B/2011/40 toTomasz Sulej, Polish Academy of Sciences). G. Niedźwiedzki is currentlyfunded by a Wallenberg Scholarship grant awarded to P. E. Ahlberg(Uppsala University). We thank Spencer G. Lucas and an anonymousreviewer for comments and suggestions that improved this paper. Thisproject aims to contribute to IGCP 630 ‘Permian–Triassic climatic andenvironmental extremes and biotic response’. Larry Rinehart is thankedfor the improvement of the English and some valuable hints.

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Early Triassic Conchostracans (Crustacea: Branchiopoda) from the terrestrial Permian–Triassic boundary sections in the Moscow syncline