GeolCarp_Vol69_No1_3

GEOLOGICA CARPATHICA

, FEBRUARY 2018, 69, 1, 3–16

doi: 10.1515/geoca-2018-0001

www.geologicacarpathica.com

A Middle Triassic pachypleurosaur

(Diapsida: Eosauropterygia) from a restricted carbonate

ramp in the Western Carpathians (Gutenstein Formation,

Fatric Unit): paleogeographic implications

ANDREJ ČERŇANSKÝ



, NICOLE KLEIN

, JÁN SOTÁK

3, 4

, MÁRIO OLŠAVSKÝ

JURAJ ŠURKA

, and PAVEL HERICH

6, 7

Department of Ecology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, 84215, Bratislava, Slovakia;



cernansky.paleontology@gmail.com

Steinmann-Institute, Division of Paleontology, University of Bonn, Nußallee 8, 53115 Bonn, Germany

Earth Science Institute, Slovak Academy of Sciences, Ďumbierska 1, 974 01 Banská Bystrica, Slovakia

Department of Geography, Faculty of Education, KU Ružomberok, Hrabovská cesta 1, 03 401 Ružomberok, Slovakia

State Geological Institute of Dionýz Štúr, Lazovná 10, 974 01 Banská Bystrica, Slovakia

Demänovská dolina Valley Caving Club, Ploštín 91, 03101 Liptovský Mikuláš, Slovakia

Slovak Caves Administration, Hodžova 11, 03101 Liptovský Mikuláš, Slovakia

(Manuscript received May 17, 2017; accepted in revised form December 12, 2017)

Abstract: An eosauropterygian skeleton found in the Middle Triassic (upper Anisian) Gutenstein Formation of the Fatric

Unit (Demänovská dolina Valley, Low Tatra Mountains, Slovakia) represents the earliest known occurrence of marine

tetrapods in the Western Carpathians. The specimen represents a partly articulated portion of the postcranial skeleton

(nine dorsal vertebrae, coracoid, ribs, gastral ribs, pelvic girdle, femur and one zeugopodial element). It is assigned to

the Pachypleurosauria, more precisely to the Serpianosaurus–Neusticosaurus clade based on the following combination

of features: (1) small body size; (2) morphology of vertebrae, ribs and femur; (3) tripartite gastral ribs; and (4) micro-

anatomy of the femur as revealed by µCT. Members of this clade were described from the epicontinental Germanic Basin

and the Alpine Triassic (now southern Germany, Switzerland, Italy), and possibly from Spain. This finding shows that

pachypleurosaur reptiles attained a broader geographical distribution during the Middle Triassic, with their geographical

range reaching to the Central Western Carpathians. Pachypleurosaurs are often found in sediments formed in shallow,

hypersaline carbonate-platform environments. The specimen found here occurs in a succession with vermicular lime-

stones in a shallow subtidal zone and stromatolitic limestones in a peritidal zone, indicating that pachypleurosaurs

inhabited hypersaline, restricted carbonate ramps in the Western Carpathians.

Keywords: Reptilia, osteology, Gutenstein Limestone, Low Tatra Mountains, Mesozoic.

Introduction

Occurrences of vertebrates are extremely rare in the Triassic

deposits of the Western Carpathians. With the exception of the

late Triassic dinosaur tracks from the Tomanová Formation of

the Tatra Mountains (Michalík et al. 1976; Michalík & Kundrát

1998; Niedźwiedzki 2011), no tetrapod remains were descri-

bed until now. Therefore, the paleogeographic and paleo-

environmental distribution of Mesozoic reptiles in this region

is poorly documented. Here, we describe an eosauropterygian

skeleton, which represents an earliest Triassic vertebrate

skele ton found in the Western Carpathians. The specimen was

found in the Gutenstein Formation of the locality Štefanová

Cave (Fig. 1; Demänovská dolina Valley, the Low Tatra Moun-

tains). The deposits are of Late Anisian age (e.g.,

Bystrický

1970;

Havrila in Biely et al. 1997; the age is based on brachio-

pods, echinoderms, conodonts and dasycladacean algae, see

below).

Sauropterygia represent a diverse group of marine reptiles

that existed from the late Early Triassic until the end of the

Cretaceous (Rieppel 2000; Motani 2009). The Triassic radia-

tion consists of shallow marine Placodontia, Pachypleurosauria,

and Nothosauria as well as the more open marine Pistosauria.

In contrast, the Jurassic and Cretaceous seas were ruled by the

open marine Plesiosauria. Pachypleurosauria, Nothosauria

and Pistosauria form the Eosauropterygia (Rieppel 2000).

Their monophyly has been challenged due to the description

of several new taxa from the Middle Triassic of China (e.g.,

Jiang et al. 2008; Shang et al. 2011; Wu et al. 2011), which

exhibit a mosaic of pachypleurosaurian and nothosaurian

characters, questioning the monophyly of pachypleurosaurs

and nothosaurs (Wu et al. 2011; Ma et al. 2015). Isolated bones

of Sauropterygia are the most common skeletal elements in

the Muschelkalk bone beds of the Germanic Basin and are

numerous in the Alpine Triassic. They are also quite common

in the Middle Triassic of the eastern Tethyan (now South

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China) faunal provinces. Sauropterygia have never been docu-

mented from the Western Carpathians.

Pachypleurosauria are small (<120 cm) and have a long

neck and tail as well as an elongated trunk region. They are

interpreted as anguilliform swimmers, preferring hypersaline

habitats and most likely feeding on small invertebrates/arthro-

pods (e.g., Sues 1987; Rieppel 1989). Some pachypleurosaurs

were viviparous [(Cheng et al. 2004); it should be noted that

although the tiny specimen of Neusticosaurus was identified

as an embryo by Sander (1988), the direct evidence for vivi-

parity is restricted to the chinese taxon Keichousaurus, which

is, however, frequently considered closer to nothosaurs (see

Holmes et al. 2008)]. Pachypleurosaurs from the Alpine

Triassic of Monte San Giorgio and China show morphological

adaptations for swimming such as trunk shape, body ratios

(e.g., neck, trunk, and tail lengths), simplification of limb

bones, reduction of carpal and tarsal bones, and pronounced

pachyostosis of vertebrae and ribs. Their long bones are

pachyosteosclerotic (Hugi et al. 2011). Members of the

Serpianosaurus–Neusticosaurus clade (Alpine Triassic;

Sander 1989; Rieppel 1989, 2000) and Keichousaurus

(Guizhou province; Lin & Rieppel 1998; Cheng et al. 2009;

Xue et al. 2015) were highly abundant (with hundreds of com-

plete skeletons found in the Alps and China).

The aims of this paper are: (1) an anatomical description of

the skeleton; (2) its taxonomical allocation based on morpho-

logy, including data revealed from µCT; and (3) the paleogeo-

graphic and paleoecological implications of this find for the

distribution of pachypleurosaurs during the Middle Triassic in

the Western Carpathians.

Material and methods

The fossil skeleton (for measurements, see Table 1) was

found in

Štefanová Cave (Demänovská dolina Valley, Slovakia)

within

the Gutenstein Limestone. The find was made by cavers

from the

P. H. group (Demänovská dolina Valley Caving Club)

and was excavated by the authors A. Č., M. O. and J. Š.

The studied specimen is housed

in the Slovak Museum of

Nature Protection and Speleology, Liptovský Mikuláš

(Slovakia) and prefixed by P

15136

. Standard anatomical

orientation is used throughout this article.

The specimen was

scanned using the micro-computed tomography (µCT) facility

at the Slovak Academy of Sciences in Banská Bystrica,

using a Phoenix mikro-CTv|tome|x L240 with the following

settings:

VxSize = 0.05978500; Current = 220; Voltage = 220;

Inttime = 20000; Average = 3; Steps360 = 2400. The images

were recorded over 360°. Data were analysed using

Avizo 8.1

on a high-end computer workstation at the Department of

Ecology (Comenius University in Bratislava). The photo-

graphy of the fossil is from a D610 Nikon camera. The paleo-

geographic map was modified using modified data from

several authors (Michalík & Kováč 1982; Häusler et

al. 1993; Michalík 1993, 1994; Stampfli 1996; Diedrich

2009; Renesto 2010; Stockar et al. 2012; Beardmore &

Furrer 2016).

Geological setting

The cave system of the Demänovská dolina Valley is located

in the region of the Low Tatra Mountains in north-central

Slovakia (Fig. 1A).

The remains of the skeleton were reco-

vered from dark grey bedded limestones inside the Štefanová

Cave (in the part of the cave called “Eldorádo”), 26 metres

directly below the river Demänovka (GPS

48°59’25.398 N,

19°35’21.32 E)

. These limestones belong to the Gutenstein

Formation, which is well known from the Middle Triassic

sequence of Austroalpine and Central Western Carpathian

units. This formation was defined by Hauer (1853) and

intended as a dark to grey-black bedded limestones with white

carbonate veins, which alternated in their lower part with

schists of the Werfen Formation and in their upper part

(Annaberg Limestone sensu Tollmann 1966) with dolomites

of the Ramsau Formation. In the Western Carpathians, similar

limestones were also named as the Vysoká Formation (Vetters

1904), which is characterized by the presence of oolitic, bio-

stromal, tempestite and sebkha-type carbonates (Michalík et

al. 1992; Michalík 1997).

Length of articulated part of the trunk column

Length/width/height of preserved vertebrae I-IX (measured in

anteroposterior direction)

3.3/9.8/4.5 – 5.7/9.3/6.3 – 5.4/9.5/6.8 – 5.4/9.6/7 – 5.4/9.1/6.6 –

5.3/9.2/6.8 – 5.3/8.8/6.8 – 5.3/8.4/6.4 – 4.8/7.5/6.6

Length of complete ribs (measured in anteroposterior direction)

Length of gastralia

Length and width of incomplete coracoid

Length / width of incomplete right and left pubis

12.6/14.2 - 13/17

Length of incomplete femur

Midshaft width of femur

3.3

Width/thickness of proximal femur head

4.2

Length and width of incomplete zeugopodial element

Table 1: Measurements and dimensions of P 15136 in millimeters.

ČERŇANSKÝ, KLEIN, SOTÁK, OLŠAVSKÝ, ŠURKA and HERICH

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, 2018, 69, 1, 3–16

The Middle Triassic carbonates of the Demänovská Dolina

Valley are divided into the Gutenstein Formation, Annaberg

Limestone and Ramsau Formation (Fig. 1B). They were

already studied by Štúr (1868). He considered that they

belonged to the Muschelkalk. The sequence described by Štúr

(l.c.) comprises dark dolomitic limestones, crinoidal lime-

stones with Encrinus lilliformis and coquina limestones with

brachiopods and bivalves (e.g., Decurtella decurtata,

Spiriferina fragilis, Sp. mentzelii, Terebratulla vulgaris,

Pecten discites). These fossils proved the Anisian age of the

Gutenstein Limestone (Kettner 1927; Matějka & Andrusov

1931). Bioclastic limestones below the base of the Ramsau

Dolomite Formation also contain the Anisian dasycladacean

algae, such as Physoporella dissita, Ph. praealpina, Diplopora

annulatissima (Bystrický 1970; Biely et al. 1997). Diplopora-

bearing limestones were recorded at several sites in the vici-

nity of the Demänovská Dolina Valley (e.g., Lúčky and Siná

hill — Biely et al. 1997; Demänovská Cave of Liberty —

Volko Starohorský 1950). In the uppermost part of the

Gutenstein Formation, bioclastic limestones with cherts are

also present. They contain holothurian sklerites

Theelia

immisorbicula and Theelia sp., as well as the conodonts

Prionidina mülleri, Gondolella cf. constricta, Neohindonella

sp., Gondolella excelsa, and Gondolella hanbulogi (Havrila in

Biely et al. 1997). These microfossils indicate that the transi-

tion between the Gutenstein Limestone Formation and the

Ramsau Dolomite Formation corresponds to the Pelsonian /

Illyrian boundary (i.e. Middle to early Late Anisian).

The reptile skeleton was found in peritidal facies of the

Gutenstein Formation in the Štefanová Cave section (Fig. 1C).

Similarly as in other successions of the Gutenstein Formation

in the Alps and Carpathians, they were deposited on muddy

tidal flats affected by episodic high-energy storm events

(Mišík 1968, 1972; Michalík et al. 1992; Michalík 1997; Hips

1998, 2007; Rüffer & Bechtädt 1998; Bechtel et al. 2005;

Rychliński & Szulc 2005; Gaál 2016). These facies reveal sed-

imentary environments of the Anisian carbonate platform,

which was developed in the Western Carpathian area (Fig. 2).

Facies analysis of sedimentary environments

The Štefanová Cave section is composed of shallow sub-

tidal to peritidal facies types, with vertical stacking implying

Fig. 2. Monoclinal carbonate ramp of the Gutenstein Formation within Triassic platform-basin system of the Central Western Carpathians.

Explanation: 1 — carbonate ramp facies; 2 — continental facies; 3 — lagoonal hypersaline dolomites; 4 — reefal facies of rimmed platforms;

5 — basinal facies; 6 — pluvial terrigenous facies; 7 — sebkha-type dolomite facies; 8 — lagoonal peritidal facies; 9 — terrigenous red-bed

facies; 10 — swamp and estuarine facies; 11 — biostrome intra-platform facies (adapted from Michalík 1977 and completed by facies types of

lithostratigratigraphic formations).

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a cyclic nature of deposition. Subtidal facies are formed by

dark-grey bedded limestones (Fig. 3A) with mudstone to

wackestone microfacies, evaporate pseudomorphs (so-called

birdseyes — Fig. 3B), pellets (coprolites) and thick-walled

ostracods. The rare species Meandrospira deformata (Fig. 3C)

belongs to the foraminifers with ecological adaptation to

hypersaline facies (Salaj & Polák 1978). Subtidal facies

indicate a low-energy hypersaline environment on a restricted

carbonate ramp.

Shallow subtidal facies were colonized by burrowing orga-

nisms (Fig. 3D). The limestones are heavily bioturbated by

Thalassinoides (Fig. 3E), the burrows of which are sometimes

truncated by erosional surfaces and dispersed to worm-like

structures known as vermicular limestones. It seems that bio-

turbated lime mud sediments were eroded by ephemeral storm

currents. Trace fossil abundance was probably related to the

hypersaline conditions of the Anisian carbonate ramp (see

Jaglarz & Uchman 2010).

The subtidal facies are overlain by intertidal facies with

crypt algal lamination (Fig. 3F). The limestones exhibit a micro-

bial wrinkle structures of algal muds, fenestral structures and

desiccative pores. The presence of these microbial and subaerial

structures indicates shallow-water tidal flat environments of

restricted lagoons with intermittently exposed conditions.

Intertidal flat deposits are bounded by erosional scours and

overlain by cross-stratified beds of bioclastic limestones

(Fig. 3F–I). These limestones are rich in birdseye particles,

intraclasts, peloids, skeletal grains of crinoids, foraminifers

(e.g., Glomospirella lampangensis, Pilamminella cf. gemerica)

and ostracod shells (Fig. 3G, H, J). Cross-stratified beds in the

Gutenstein Limestone could be interpreted as deposits of shal-

low tidal channels or sedimentary lags filled by tempestites.

Their ripple cross-stratification also resembles imbricated

structures from storm-dominated Anisian carbonate ramps in

the Central Western Carpathians (Malé Karpaty Mts., Michalík

et al. 1992; Michalík 1997; High Tatra Mountains, Jaglarz &

Szulc 2003), Aggtelek-Rudabánya Mountains (Hips 1998)

and the Germanic Basin (Schwarz 1975).

The Gutenstein Formation at the Štefanová Cave section

was deposited in shallowing-upward cycles that capture

a transition from shallow subtidal to peritidal zones and from

low-energy to high-energy environments. The fossil skeleton

of the pachypleurosaur was found in the shallowest part of the

peritidal sequence, where gradual shoaling led to formation of

intertidal algal mats in restricted hypersaline lagoons (Fig. 1C

— F3 facies type of cryptalgal limestones). Vermicular lime-

stones from shallow subtidal environments can also indicate

a higher salinity, which suggest that pachypleurosaurs inha-

bited as swimmers hypersaline waters of the shallow carbo-

nate ramp.

Systematic paleontology

It should be noted that some authors (Wu et al. 2011; Ma et

al. 2015) did not find support for the clade Pachypleurosauria

rather than Eosauropterygia. The taxa previously included in

the Pachypleurosauria were found to be scattered in the pecti-

nate basal part of the Eosauropterygian tree. According to

these authors, Sauropterygia includes the Placodontia and the

Eosauropterygia, the latter containing the “pachypleuro-

saur-grade” taxa, and the monophyletic Nothosauroidea and

Pistosauroidea (comprising plesiosaurs). Other recent phylo-

genetic hypotheses, however, with discordant results have

been published (e.g., Lee 2013). The resolving of these

conflicts between results from data sets

is beyond the aim of

this paper and we choose to retain Pachypleurosauria as a

valid taxon here.

Sauropterygia Owen,1860

Eosauropterygia Rieppel, 1994

Pachypleurosauria Nopcsa, 1928

Pachypleurosauria indet. aff. Serpianosaurus Rieppel, 1989/

Neusticosaurus Seeley, 1882

(Figs. 4–7)

Referred specimen: partly articulated skeleton comprising

associated parts of the posterior trunk region P 15136

Horizon:

Gutenstein Limestone Formation of the

Demä-

novská Cave system in the Low Tatra Mountains, middle to

early late Anisian, lower Middle Triassic.

Locality: Štefanová Cave (Demänovská dolina Valley,

Slovakia), 48°59‘25.398 N, 19°35‘21.32 E.

Description

Dorsal vertebrae: Nine articulated dorsal vertebrae are pre-

served in anatomical position (Figs. 4, 5). In dorsal view they

appear swollen (pachyostotic). The anteroposteriorly elon-

gated centra are shallowly amphicoelous. In lateral aspect,

the centrum is constricted and slightly concave (Fig. 6C).

The synapophyses are large and protrude strongly laterally

(Fig. 6). The neural canal is small and rounded. The neural

spine, which is most completely preserved on the 4

vertebra

(counted from posterior; see Fig. 6A–E) is rectangular in

shape and longer than high. Pre- and postzygapophyses are

small, only slightly inclined from a horizontal plane. They

possess articulation areas that are not laterally expanded, but

more-or-less directed anteroposteriorly.

Ribs: Seven ribs are well preserved on the left side

(Fig. 5). They are robust and curved. The curvature is espe-

cially distinct in the anterior ones, where the ribs are markedly

bent in the proximal third of their length. The last two poste-

riorly located ribs are slightly smaller relative to the others.

Rib thickness is largest along the proximal articulation area.

They are single-headed. Distally the ribs end bluntly.

Gastral ribs: The preserved gastral ribs are well ossified

(Fig. 4). These elements are only preserved in the posterior

section of the specimen. They consist of three parts, gradually

diverging posterolaterally (see Rieppel 2000). There is a broad

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medioventral element, possessing an anterior projection and

a slender lateral element on either side of it.

Coracoid: The element occupying the anterior region of the

preserved skeleton is interpreted here as a coracoid (Fig. 5).

Unfortunately, this element is badly preserved — heavily

weathered and damaged. It is flat but robustly built. The mid-

dle portion is typically constricted, which is expressed espe-

cially on one side. This side is regarded as the medial margin,

because according to Rieppel (1989), this margin is typically

more concave than the lateral one.

Pelvic girdle: The pubis is preserved on both sides, although

its original shape is difficult to determine because its margins

are damaged (Fig. 7A–C). The bone is essentially a flat

element. Its thickness gradually decreases medially, whereas it

is more robust around the acetabulum. It is slightly constricted

in its mid-region, however, this is preserved only on one side.

The dorsal side is weakly angulated. The ventral side of both

right and left elements possesses grooves (two in the left and

one in the right pubis). However,

these grooves were most

likely caused by postmortem and fossilization processes (they

may be, e.g., bore holes of clionid sponges). The bone

pierced by a small obturator foramen in its posterior margin,

where it contacts the ischium, which is close to the elliptical

acetabulum. The obturator foramen is almost fully enclosed in

the pubis, although a small shallow notch on the ventral sur-

face runs from the foramen to the margin. The bony septum,

Fig. 4.

A — The pachypleurosaur skeleton P 15136 from Štefanová Cave in Gutenstein Limestone. B — CT visualization of the find.

C — detail of visible gastral ribs.

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which surrounds the foramen is porous. Incomplete remains of

another element, which are located medially between the right

and left pubis, is interpreted here as the ischium.

Femur: Only the proximal to midshaft part of the femur is

preserved. The diaphysis is elongated and nearly straight, the

proximal head not offset. In the region close to the proximal

region, rugosities on the surface are present. The midshaft

cross section is typically round (Fig. 7D).

CT data revealed microanatomical information from the

oval cross section of midshaft area (Fig. 7D). The femur has

a central large medullary region that is filled by tissue and

scattered with few erosional cavities appearing as dark spots

in Fig. 7D. Thus, the femoral cross sections reveal osteo-

sclerosis. The medullary region is surrounded by a distinct

dark ring, which is most likely the sharp line of Klein (2010)

and Hugi et al. (2011) representing the border between endo-

steal and periosteal domains. Details of the bone tissue and of

the vasculary system cannot be made out.

Zeugopodial bone: A fragment of a zeugopodial element is

preserved. It is compressed, resulting in a markedly elliptical

cross-section. Due to the size of the element (Table 1) in com-

parison to the femur, it could well represent the tibia.

Discussion

Taxonomic assignment

The small size and the morphology of the preserved elements

such as the pachyostotic vertebrae and proximal ribs, as well

as the tripartite gastral ribs clearly point to affinities with the

pachypleurosaur Neusticosaurus, or at least with the

Neusticosaurus + Serpianosaurus clade (Rieppel 1989, 2000;

Sander 1989). In the specimen P 15136, the number of gastral

ribs is estimated on the basis of the preserved portion. In any

case, even if the total number of elements would be five, this

would be not in contrast with our assignment to the pachypleu-

rosaurs, since gastral ribs are composed of five elements each

in primitive pachypleurosaurs such as Serpianosaurus as well

(see Rieppel 1989). However, the incorporation of five elements

in a gastral rib is regarded as representative of the plesiomor-

phic condition and thus cannot be diagnostic (Rieppel 1989;

e.g., the nothosaur Lariosaurus, which also includes small

representatives, has 5-part gastral ribs as well). The shape and

preserved morphology of the girdle elements, although all

highly incomplete, and of the femur support our assignment.

Fig. 7.

The Triassic pachypleurosaur P 15136 from Štefanová Cave.

Pubis in: A — dorsal; B — ventral and C — posterior view. D — femur in

cross-section revealed from µCT.

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The femoral cross sections reveals a compact medullary region

resulting in osteosclerosis similar to what was described for

Neusticosaurus and Serpianosaurus (Hugi et al. 2011) and

contrary to the condition in the pachypleurosaur Anarosaurus

heterodontus and Nothosaurus spp., which have a free cavity

at femur midshaft (Klein 2012; pers. obs. of N. K.).

A more precise identification is not possible due to the

incompleteness of P 15136 and due to the general lack of diag-

nostic characters in the postcranial skeleton of Pachy-

pleurosauria. An unambiguous assignment to Eosauropterygia

is often only possible when a skull is preserved on which alpha

taxonomy is usually solely based (e.g., Rieppel 2000; Klein

2012; Klein et al. 2016a).

According to Rieppel & Hagdorn (1997, 1998), the

Serpianosaurus–Neusticosaurus clade originated in the Alpine

Triassic at a time around the Anisian–Ladinian boundary and

diversified in the southern Alpine intraplatform basin from

where hundreds of complete individuals are known (e.g.,

Sander 1989; Rieppel 2000). Whereas Serpianosaurus was

restricted to the Alpine Triassic of Monte San Giorgio (Italy

and Switzerland), Neusticosaurus spp. was more widespread

and is also documented in southern Germany (early Ladinian/

Lettenkeuper of Hoheneck; Seeley 1882; Rieppel & Lin

1995). A possible member of the Serpianosaurus–

Neusticosaurus clade was also reported from Spain (Rieppel

& Hagdorn 1998). Other eosauropterygians, however, have

been collected in Israel and Saudi Arabia (Rieppel 2000).

Our find now proves that the Serpianosaurus–

Neusticosaurus clade was even more widely distributed in

Europe during the Middle Triassic than previously thought

and that they inhabited the marine environments of the Western

Carpathians already during the late Anisian.

Paleogeographic and paleoecological implications

Pachypleurosaurs were typically near-shore inhabitants,

sticking to shallow marine environments (Sues 1987; Rieppel

1989; Rothschild & Storrs 2003). They show few morpho-

logical adaptations to swimming and seem not to have been

very efficient swimmers or divers (Carroll & Gaskill 1985;

Fig. 8. Paleogeographic sketch map of the European – western Tethyan realm in the Middle Triassic period (after Michalík & Kováč 1982;

Häusler et al. 1993; Michalík 1993, 1994; Stampfli 1996; Diedrich 2009; modified). 1 — dry land; 2 — epicontinental sea; 3 — carbonate

platforms of the Alpine–Carpathian shelf; 4 — carbonate platforms of the Apulia shelf; 5 — Paleo-Tethyan oceanic basin; 6 — pachypleuro-

saurs and their possible migratory routes from Germanic basin to Carpathian basins (full red line indicates more presumable route than that of

dashed line). Asterisk — indication of Monte San Giorgio locality with abundant fossil record of pachypleurosaurs in Southern Alps (see

Renesto 2010; Stockar et al. 2012; Beardmore & Furrer 2016).

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Hugi et al. 2011), in contrast to other members of Sauropterygia

that lived at the same time (e.g., Rieppel 2000; Klein et al.

2015, 2016b). At localities from the eastern Tethyan faunal

provinces (now South China), the environments that yielded

high numbers of pachypleurosaurs are interpreted as hyper-

saline (Wang et al. 2008). It should be noted that terrestrial

land was close to all these localities.

A preference for shallow marine and hypersaline habitats

fits well with the paleoenvironmental conditions suggested for

the Gutenstein Formation, which is interpreted as a mono-

clinal carbonate ramp (Michalík et al. 1992; Hips 1998), with

sedimentological, ichnological, and

geochemical evidence for

hypersaline conditions (Mišík 1972; Spötl 1988, Jaglarz &

Uchman 2010). Birdseye, stromatolitic and vermicular facies

at the Štefanová

Cave section indicate that pachypleurosaurs

inhabited environments with hypersaline conditions

The preser-

vation of associated elements of the incomplete skeleton

P 15136 rules out long-distance

transport

and indicates that

the specimen is not allochthonous.

The interpretation of the Gutenstein Formation of

Demänovská dolina Valley (shallow marine carbonate ramp,

sedimentation in a shallow subtidal to peritidal environment)

as well as the presence of a marine reptile in this layer can

indicate the presence of a coast nearby and/or at least some

elevated areas such as small islands. The European pachy-

pleurosaurs are assumed to be anguiliform swimmers (e.g.,

Caroll & Gaskill 1985; Lin & Rieppel 1998; Houssaye 2012),

but with the inability to dive deeply (Rieppel 1989). Moreover,

it has been suggested that the forelimbs of small European

pachypleurosaurs are also used for terrestrial locomotion

(Sander 1989; Lin & Rieppel 1998). Although sedimento-

logical evidence from the Anisian formations in the Central

Carpathian units does not indicate any presence of terrestrial

habitats (Fig. 8), presence of small islands (peritidal environ-

ments are typically associated with barrier islands, channels)

can be rather inferred from facies differentiation and shallo-

wing upward cyclicity generated by migrating islands.

Acknowledgements: We are indebted to Krister T. Smith

(Senckenberg Research Institute and Natural History Museum

in Frankfurt am Main) for English corrections. For critically

reading the manuscript and the text corrections, we thank

A. Tomašovych, J. Michalík (both Slovak Academy of Sciences)

and S. Renesto (Insubria University). We thank the Slovak

Museum of Nature Protection and Speleology in Liptovský

Mikuláš for the access and permission to take the fossil out.

This project was supported by projects APVV-14-0118 from

the Slovak Research and Development Agency, and by grant

2/0034/16 from the VEGA Scientific Agency.

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