Dawazisaurus brevis: a new Middle Triassic Eosauropterygian From China

Dawazisaurus Brevis, A New Eosauropterygian From the Middle Triassic of Yunnan, China

Authors:

Chen et al

Abstract:


Dawazisaurus brevis (gen. et sp. nov.) is a newly discovered Triassic marine reptile, represented by a complete skeleton from Member II of the Guanling Formation of Luoping, Yunnan Province, China. This paper aims to (1) present a thorough description of the species, (2) make a detailed comparison to demonstrate if the species can be referred to any known sauropterygian taxa, and (3) conduct phylogenetic analyses to establish the internal relationships of the species with other sauropterygians. In addition, the discovery of Dawazisaurus provides a chance not only to test the phylogenetic patterns of the Sauropterygia obtained by previous studies but also to evaluate the previous hypotheses on the origin of the sauropterygian groups at different levels. D. brevis is an eosauropterygian, characterized by a unique combination of derived features such as a pair of large nasals joining in the formation of the internarial septum, a short trunk with 16 dorsal vertebrae; the zygapophyses of the trunk vertebrae very small or weakly developed; the posterior margin of the skull roof deeply V-shaped, and an ossified distal carpal 5. Phylogenetic analysis indicates that D. brevis appears to be more closely related to the Nothosauroidea than the Pistosauroidea within the Eosauropterygia.

Kawanectes lafquenianum: a new Elasmosaurid Plesiosaur From Campanian/Maastrichtian Cretaceous Patagonia

A SMALL BODY SIZED NON-ARISTONECTINE ELASMOSAURID (SAUROPTERYGIA, PLESIOSAURIA) FROM THE LATE CRETACEOUS OF PATAGONIA WITH COMMENTS ON THE RELATIONSHIPS OF THE PATAGONIAN AND ANTARCTIC ELASMOSAURIDS

Author:

O'Gorman

Abstract:

The systematics of the Late Cretaceous non-aristonectine elasmosaurids from Argentinean Patagonia are poorly known as there is no valid species currently recognized. Here a new non-aristonectine elasmosaurid: Kawanectes lafquenianum nov. comb. from the late Campanian–early Maastrichtian Allen Formation is diagnosed. Kawanectes lafquenianum is a distinctively small-bodied sized non-aristonectine elasmosaurid characterized by caudal vertebrae with marked laterally projected parapophyses, presence of pelvic bar, high ratio (~1.2) between humerus/femur length and a large posterodistal projection of the humerus which bears a posterior accessory articular facet. A phylogenetic analysis recovered K. lafquenianum closely related with Morenosaurus stocki, Vegasaurus molyi and Aristonectinae, showing the relationships between the elasmosaurids from Patagonia, Western Antarctic, and the Pacific coast of the USA. Kawanectes lafquenianum is part of the fauna of the coeval Allen and La Colonia formations that also comprises indeterminate aristonectines and polycotylids . This relatively high diversity plesiosaur fauna includes the three main morphotypes (aristonectines, non-aristonectines elasmosaurids and polycotylids), which is remarkable since the depositational environments of the Allen have been inferred as marginal marine to non-marine environments.

Makhaira rossica: a new Pliososaur With Crocodile Like Teeth From Hauterivian Cretaceous Russua

Peculiar macrophagous adaptations in a new Cretaceous pliosaurid

Authors:

Fischer et al

Abstract:

During the Middle and Late Jurassic, pliosaurid plesiosaurs evolved gigantic body size and a series of craniodental adaptations that have been linked to the occupation of an apex predator niche. Cretaceous pliosaurids (i.e. Brachaucheninae) depart from this morphology, being slightly smaller and lacking the macrophagous adaptations seen in earlier forms. However, the fossil record of Early Cretaceous pliosaurids is poor, concealing the evolution and ecological diversity of the group. Here, we report a new pliosaurid from the Late Hauterivian (Early Cretaceous) of Russia. Phylogenetic analyses using reduced consensus methods recover it as the basalmost brachauchenine. This pliosaurid is smaller than other derived pliosaurids, has tooth alveoli clustered in pairs and possesses trihedral teeth with complex serrated carinae. Maximum-likelihood ancestral state reconstruction suggests early brachauchenines retained trihedral teeth from their ancestors, but modified this feature in a unique way, convergent with macrophagous archosaurs or sphenacodontoids. Our findings indicate that Early Cretaceous marine reptile teeth with serrated carinae cannot be unequivocally assigned to metriorhynchoid crocodylomorphs. Furthermore, they extend the known diversity of dental adaptations seen in Sauropterygia, the longest lived clade of marine tetrapods.

Dianmeisaurus gracilis: A new Small-sized Eosauropterygian From Anisian Triassic Luoping

A new small-sized eosauropterygian (Diapsida: Sauropterygia) from the Middle Triassic of Luoping, Yunnan, southwestern China

Authors:

Shang et al

Abstract:

A new eosauropterygian, Dianmeisaurus gracilis gen. et sp. nov. is described based on a nearly complete skeleton from the Member II of Guangling Formation (Anisian) of Luoping County, Yunnan Province. It is a small-sized (with a total length of less than 50 cm) sauropterygian with a slender body. This new species is similar superficially to two other smallsized eosauropterygians, Diandongosaurus Shang et al., 2011 and Dianopachysaurus Liu et al., 2011a, which were also collected from the same stratum of Luoping, in the body proportion, the skull with no contracted snout, and an oval orbit extremely larger than supratemporal fenestra. However, the new species is characterized by an extremely narrowed interorbital septum, the mandibular articulation at the level of occipital condyle, the big and stout anterolateral process of the clavicle, the proximal part of the ulna much wider than the distal end, and the presence of 41 presacral vertebrae. Furthermore, the new species differs from Diandongosaurus in having the preorbital region shorter than the postorbital region, the prefrontal with no contact of the postfrontal along the dorsal margin of the orbit, the short mandibular symphysis with the entrance of the splenial, and the premaxillary and anterior dentary teeth fang like but not king-sized. Additionally, the anterolateral process of the clavicle is very sharp and slender in Diandongosaurus. Compared with the Dianopachysaurus, the new species is different in having no pachyostosis of the caudal ribs, no more than three carpal ossifications, and the rounded astragalus. Our phylogenetic analyses suggest that Dianmeisaurus is probably the sister group of Diandongosaurus. The two genera, together with the Majiashanosaurus, Keichousaurus, and Dianopachysaurus are grouped in a monophyletic clade and phylogenetically more closely related to the Nothosauroidea than the European pachypleurosaurs (Dactylosaurus, Anarosaurus, Serpianosaurus, and Neusticosaurus). The coexist of three small-sized eosauropterygians indicates that sauropterygians were a highly diversified group of marine reptiles in the Luoping fauna, Yunnan Province during the early Middle Triassic.

Polycotylus latipinnis: a Redescription of Polycotylid Plesiosaur From Campanian Cretaceous South Dakota

Polycotylus latipinnis Cope (Plesiosauria, Polycotylidae), a nearly complete skeleton from the Niobrara Formation (Early Campanian) of southwestern South Dakota

Authors:

Schumacher et al

Abstract:

A nearly complete skeleton of Polycotylus latipinnis (SDSM 23020) from the upper Niobrara Formation (early Campanian) of South Dakota (U.S.A) greatly improves information for this formerly poorly known taxon. Specimens SDSM 23020 and YPM 1125 (paratype P. latipinnis) exhibit numerous postcranial characters that distinguish Polycotylus, in particular presacral vertebral count, nature of chevron facets, unique ilia, and highly derived paddles including five epipodial ossifications and increased hyperphalangy. Greater vertebral and phalangeal counts of Polycotylus are accompanied by exceptional foreshortening; thus, the relative body and limb proportions are likely similar to less derived polycotylids, with fewer, more elongate vertebrae and phalanges. The complete skull, derived among polycotylids, has short temporal fenestrae, elongate frontals, exceptionally slender parasphenoid with prominent cultriform process, and exceptionally long extensions of the angulars and splenials within the mandibular symphysis. Cladistic analysis indicates that Polycotylus nests firmly within derived Polycotylidae as a potential sister taxon to Dolichorhynchops osborni and Trinacromerum, despite a ‘primitive’ presacral vertebral count. Future improvements in available data, in particular better information regarding basal polycotylids, and refinement of character selection to nullify homoplasy could significantly alter the tree structure to show distinct subgroups within Polycotylidae. North American polycotylids with elongate temporal fenestrae, elongate podials, and relatively long vertebrae are confined to occurrences of late Cenomanian and earliest Turonian age, whereas polycotylids distinctly foreshortened in these respects are restricted to post-Turonian occurrences. Ilium morphology is highly variable among polycotylids and, in addition to taxonomic utility, may be in part attributable to sexual dimorphism.

Prolacertilians and Eosauropterygians From Early Triassic Donskaya Luka, Russia

New data on the herpetofauna of the Early Triassic Donskaya Luka locality, Volgograd Region

Authors:

Sennikov

Abstract:

New material of Early Triassic prolacertilians and eosauropterygians from the Donskaya Luka locality is described. New data on the morphology and functional morphology of these reptile groups are provided; their taxonomy, phylogeny, and lifestyle are discussed.

A Very Complete Triassic Plesiosaur Found in Germany

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Keichousaurus hui's Adult sex Ratio, Sexual Dismorphism and Sexual Selection

Adult sex ratio, sexual dimorphism and sexual selection in a Mesozoic reptile

Authors:

Motani et al

Abstract:

The evolutionary history of sexual selection in the geologic past is poorly documented based on quantification, largely because of difficulty in sexing fossil specimens. Even such essential ecological parameters as adult sex ratio (ASR) and sexual size dimorphism (SSD) are rarely quantified, despite their implications for sexual selection. To enable their estimation, we propose a method for unbiased sex identification based on sexual shape dimorphism, using size-independent principal components of phenotypic data. We applied the method to test sexual selection in Keichousaurus hui, a Middle Triassic (about 237 Ma) sauropterygian with an unusually large sample size for a fossil reptile. Keichousaurus hui exhibited SSD biased towards males, as in the majority of extant reptiles, to a minor degree (sexual dimorphism index −0.087). The ASR is about 60% females, suggesting higher mortality of males over females. Both values support sexual selection of males in this species. The method may be applied to other fossil species. We also used the Gompertz allometric equation to study the sexual shape dimorphism of K. hui and found that two sexes had largely homogeneous phenotypes at birth except in the humeral width, contrary to previous suggestions derived from the standard allometric equation.

The First Polycotylid Plesiosaur From Coniacian/Campanian Cretaceous Antarctica

First record of Polycotylidae (Sauropterygia, plesiosauria) from the Upper Cretaceous of Antarctica

Authors:

Novas et al

Abstract:

In the present paper we report the incomplete skeleton of an indeterminate polycotylid that includes the articulated pelvic girdle. The material was collected from the Alpha Member of the Santa Marta Formation (upper Coniacian–lower Campanian) on James Ross Island, Antarctic Peninsula. The specimen is referred to the Polycotylidae on the basis of its very elongate ischia and rimmed anterior and posterior articular surfaces of the dorsal vertebrae. Additionally, the caudal vertebrae show confluent parapophyses and neural arch facets. The present report constitutes the first record for polycotylids in Antarctica, being an important addition to the fossil marine reptile diversity. Polycotylids are a scarce component of the Weddellian herpetofauna, which are dominated by aristonectine and non–aristonectine elasmosaurids. In contrast, in Northern Hemisphere assemblages, polycotylids are an important component of the plesiosaur diversity. The scarcity of polycotylids may constitute another distinctive feature of Weddellian plesiosaur faunas.

Wangosaurus brevirostris: a new Ladinian Triassic Pistosauroid From China

A new pistosauroid (Reptilia, Sauropterygia) from the late Ladinian Xingyi marine reptile level, southwestern China

Authors:

Ma et al

Abstract:

Sauropterygia is a diverse group of Mesozoic marine reptiles that includes the Plesiosauria, one of the most successful clades from the Jurassic to the Cretaceous. The body plan of the Plesiosauria differs from that of basal sauropterygians by adaptations for life in the open ocean, as expressed by the propulsive, paddle-like limbs (Storrs, 1993; Sato et al., 2010; Benson et al., 2012). Triassic pistosauroids are believed to be important in the search for the origin of Plesiosauria (Rieppel et al., 2002; Sato et al., 2010). Until recently, the sister-group relationship between them was mainly based on cranial information, because of the generally poor preservation of Triassic pistosauroid specimens. Eight genera have been reported so far (Meyer, 1839; Yang, 1959, 1965; Storrs, 1991; Rieppel, 1997, 1998, 1999; Sander et al., 1997; Cheng et al., 2006; Dalla Vecchia, 2006), but some of these are known only from relatively complete cranial material (Augustasaurus Sander et al., 1997; Corosaurus Case, 1936; Cymatosaurus Fritsch, 1894; Pistosaurus Meyer, 1839; Yunguisaurus Cheng et al., 2006), whereas Yunguisaurus remains to date the only taxon represented by a complete skeleton.

Three genera of pistosauroids have been reported from the Triassic marine reptile faunas of southwestern China. Chinchenia sungi Young, 1965, from the upper Middle Triassic of Qingzhen, Guizhou Province, and Kwangsisaurus orientalis Young, 1959, from the upper Lower or lower Middle Triassic of Wuming, Guangxi Province, are both extremely fragmentary and listed as Pistosauroidea incertae sedis (Yang, 1959, 1965; Rieppel, 1999, 2000). Yunguisaurus liae Cheng, Sato, Wu, and Li, 2006, from the late Middle Triassic of Chajiang, Guizhou Province, and Fuyuan, Yunnan Province, is the only one represented by a complete skeleton, which is suggestive of early stages of adaptation towards the plesiosaurian functional style (Cheng et al., 2006; Zhao et al., 2008; Sato et al., 2010, 2014). Thus, more complete material should be described to provide new information that would better resolve the origin of Plesiosauria.

Here, we report a new pistosauroid, Wangosaurus brevirostris, gen. et sp. nov., from the late Middle Triassic of Xingyi, Guizhou Province, which shows a combination of plesiomorphic and derived characters (Fig. 1). Due to the rarity of complete and articulated skeletons of pistosauroids, and the presence of enough unique characters gleaned from the dorsal view of this specimen to establish a new genus, we here provide a preliminary description and phylogenetic analysis.

Cardiocorax mukulu: a new Elasmosaurid Pleisosaur From Maastrichtian Cretaceous Angola

A new elasmosaurid from the early Maastrichtian of Angola and the implications of girdle morphology on swimming style in plesiosaurs

Authors:

Araújo et al

Abstract:

We report here a new elasmosaurid from the early Maastrichtian at Bentiaba, southern Angola. Phylogenetic analysis places the new taxon as the sister taxon to Styxosaurus snowii, and that clade as the sister of a clade composed of (Hydrotherosaurus alexandrae (Libonectes morgani + Elasmosaurus platyurus)). The new taxon has a reduced dorsal blade of the scapula, a feature unique amongst elasmosaurids, but convergent with cryptoclidid plesiosaurs, and indicates a longitudinal protraction-retraction limb cycle rowing style with simple pitch rotation at the glenohumeral articulation. Morphometric phylogenetic analysis of the coracoids of 40 eosauropterygian taxa suggests that there was a broad range of swimming styles within the clade.

Paracus diepenbroeki: A new Placodont Sauropterygian From Anisian Triassic Netherlands

A new placodont sauropterygian from the Middle Triassic of the Netherlands

Authors:

Klein et al

Abstract:

A new genus and species of a non-cyamodontoid placodont is described on the basis of an incomplete and disarticulated skeleton from Winterswijk, the Netherlands, dated as early Anisian (Lower Muschelkalk). The new taxon is unique in a ventrolateral expansion of the neural arches of the posterior presacral and sacral vertebrae, in which the transverse process is incorporated. It has a round, plate-like pubis and ischium, and the only preserved long bone indicates elongated limbs. The holotype, which is relatively large (>1.35 m) for a basal sauropterygian, has still un-fused halves of neural arches and no distinct neural spine developed yet. The new taxon is assigned to non-cyamodontoid placodonts based on its round girdle elements, the morphology of dorsal-, sacral-, and caudal ribs, the straight medial and mediolateral elements of gastral ribs, and the presence of un-sutured armour plates. In spite of the large size of the holotype, there is evidence that the animal was not yet fully grown, based on the paired neural arches, and general poor ossification of the bones. The un-fused halves of neural arches are interpreted as skeletal paedomorphosis, which is typical for vertebrates with a secondary marine life style. The sacral region seems to be highly flexible.

Dwarf, Freshwater Elasmosaurs Found From Campanian/Maastrichtian Patagonia?

Late Cretaceous reptilian biota of the La Colonia Formation, central Patagonia, Argentina: Occurrences, preservation and paleoenvironments

Authors:

Gasparini et al

Abstract:

Cropping out on the southeastern margin of the Somún Curá Plateau, the La Colonia Formation (Campanian–Maastrichtian) has yielded, over the last several decades, a varied fossil tetrapod fauna (mammals, ophidians, turtles, dinosaurs, plesiosaurs, anurans). For this study several field trips were carried out specifically to recover reptile remains. Three sections, located on the southeastern slope of the Sierra de La Colonia and in the vicinity of Cerro Bayo, Chubut Province (Argentina), were selected for particular attention. The prospected sections are composed of massive, laminated or heterolithic siltstones and claystones, with scarce and thin intercalations of massive, heterolithic o cross-bedded fine sandstones and of fossiliferous conglomerates. The most abundantly recovered reptiles are terrestrial and freshwater turtles, followed by plesiosaurs and dinosaurs. Among the chelonians, more than 16 specimens of Patagoniaemys gasparinae (Meiolaniformes), three specimens of Yaminuechelys aff. Y. gasparinii (Chelidae), and the remains of a new genus of Chelidae were identified. Among the dinosaurs, theropod metatarsal fragments, an incomplete abelisaurid theropod skeleton, sauropod vertebrae, ankylosaur osteoderms and appendicular fragments of hadrosaurs were found. Among the plesiosaurs there are several well preserved elasmosaurids (including two with associated gastroliths) and a polycotylid (Sulcusuchus erraini). Except for the plesiosaurs, all the reptiles are terrestrial or freshwater taxa. However, analysis of the elasmosaurids indicates they are adult specimens of small body size, which could be related to forms that lived in restricted aquatic environments. Likewise, the polycotylid possesses deep rostral and mandibular grooves, and a conspicuous vascularization and/or innervation, that is consistent with the presence of some associated special sensory structures similar to those known in some cetaceans that inhabit modern rivers and estuaries. Sedimentological analysis suggests that deposition would have been mostly in low-energy restricted environments, like muddy plains, marshes and ponds cut by meandering channels, probably in the central mixed-energy zone within an estuary. This interpretation is consistent with the habitat inferred for the recovered reptiles, as well as with associated foraminifers and with the probable origin of gastroliths found associate with the plesiosaurs.

Xinpusaurus Revisited: A Carnian Triassic Thalattosaur From China

On the morphoplogy and taxonomic status of Xinpusaurus kohi JIANG et al., 2004 (Diapsida: Thalattosauria) from the Upper Triassic of China

Author:

Maisch

Abstract:

Additional preparation has revealed new information on the cranium and the vertebral column of the type and only specimen of Xinpusaurus kohi JIANG et al., 2004, a thalattosaur from the Upper Triassic Xiaowa Formation of Guanling County (Guizhou, south-western China). The new data allow to supplement existing descriptions and to decide on some controversial points raised in recent discussions. Although the skeleton is almost complete, there is some reconstruction, which makes the low presacral vertebral number and the narrow proximal end of the femur, originally regarded as diagnostic characters, doubtful. All other diagnostic characters of the species are valid. Comparison to another thalattosaur species from the Xiaowa Formation, Xinpusaurus bamaolinensis, shows great similarities, but is limited due to its insufficient description. Hence, it cannot be excluded that X. kohi is a junior subjective synonym of X. bamaolinensis. However, the recent claim that X. kohi and X. bamaolinensis are synonyms of X. suni, the type species of the genus, is not supported by the new data. The description of X. bamaolinensis leaves many points unclear. Pending a re-description of that specimen that may allow for a more meaningful comparison, X. kohi should be allowed to stand.

The Postcranial Skeleton of Elamosaurid Libonectes morgani From Turonian Cretaceous Texas

Postcranium of the paradigm elasmosaurid plesiosaurian Libonectes morgani (Welles, 1949)

Authors:

Sachs et al

Abstract:

Elasmosauridae constitutes one of the most immediately recognizable plesiosaurian radiations. Their distinctive body plan represents the popular model for Plesiosauria, and is typified by an osteological morphology especially adapted for hyper-elongation of the neck. Nevertheless, many archetypal elasmosaurids are known only from incomplete and/or inadequately documented material, a problem that has contributed to their uncertain intra-clade relationships. A prime example of this is Libonectes morgani from the Upper Cretaceous of Texas, USA, which is frequently presented as an elasmosaurid structural proxy because of its three-dimensionally preserved holotype skull. Perplexingly though, both the taxonomic diagnosis and phylogenetic placement of L. morgani rely primarily upon the cervical vertebrae, together with the pectoral girdle and forelimb, yet most of these elements are now lost and figured only as line drawings. We therefore reviewed the remnant postcranial skeleton of L. morgani first-hand with the objective of clarifying its defining character states. Our observations showed that the existing diagnosis of L. morgani is indeed inadequate. Moreover, the only identifiable autapomorphies occurred within the axial skeleton. This concurred with an examination of character scores used in published plesiosaurian phylogenies, and highlights the persistent significance of postcranial elements for discriminating elasmosaurid taxa.

Nothosaurus zhangi: a Very Large Nothosaur From Anisian China's Seas

A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery

Authors:

Liu et al

Abstract:

The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic.

New specimen of Placodont Psephoderma alpinum From Norian/Rhaetian Triassic Switzerland

New specimen of Psephoderma alpinum (Sauropterygia, Placodontia) from the Late Triassic of Schesaplana Mountain, Graubünden, Switzerland

Authors:

Neenan et al

Abstract:

Psephoderma alpinum is an armoured, durophagous placodont known from the alpine Late Triassic. Here we present a new, well-preserved isolated skull discovered in the Alplihorn Member (Late Norian–Early Rhaetian) of the Kössen Formation, Schesaplana Mountain, which straddles the Swiss/Austrian border. Micro-computed tomographic (µCT) scanning was used to create an accurate osteological reconstruction of the specimen, the first time this has been conducted for Psephoderma. We thus clarify disputed anatomical features from previous descriptions, such as a lack of a lacrimal and a pineal foramen that is enclosed by the parietal. We also present the first description based on µCT data of the lateral braincase wall, sphenoid region and some cranial nerve canals for Psephoderma, with the location of the hypophyseal seat, cerebral carotid foramina, dorsum sellae, prootic foramen, lacrimal foramen, as well as all dental foramina being described. This specimen represents the first skull of Psephoderma recovered in Switzerland, and features such as poorly-sutured braincase elements and its relatively small size compared to other known specimens may indicate that it was a sub-adult.

Kwangsisaurus orientalis Dated From the Anisian Triassic of China

The age of Triassic marine reptile Kwangsisaurus orientalis (Sauropterygia) from Wuming, Guangxi, China

Authors:

Shang et al

Abstract:

The holotype of Kwangsisaurus orientalis Young, 1959 is the only Triassic marine reptile specimen known from Guangxi Zhuang Autonomous Region in southern China. This fossil was collected from Wuming County in 1950s. The exact provenance of the specimen is unclear, but it has long been regarded as an Early Triassic sauropterygian following Young’s original description (Li, 2006b; Li et al., 2008; Zhao et al., 2008). The uncertainty regarding its age has introduced confusion into the studies of biogeography and evolutionary history of Chinese Triassic sauropterygians. Based on recent field work and the help of several local geologists who have knowledge of the specimen’s history, we have determined that the holotype of K. orientalis was from a quarry situated 2 km southeast of Fupeng, Suliang Village, Xianhu Township, Wuming County (Fig. 1). The type specimen was obtained from a fossiliferous bed within thin-bedded marlite, which is considered as the lower part of the Banna Formation based on lithological features. This fossiliferous bed contains abundant ammonites such as Balatonites, Protrachyceras, and Leiophyllites, in addition to some fragmentary vertebrate bones and plant debris (Figs. 1, 2). It can be identified as Middle Triassic based on the ammonites. Above it lies a tuff layer with a thickness of 10-20 cm, which is a marker bed of the Banna Formation. The tuff layer was dated to (244.2±0.7) Ma by High-precision SIMS zircon U-Pb analyses, making the age of K. orientalis Pelsonian (Anisian, Middle Triassic). The Anisian age of K. orientalis is concordant with its reidentification as a pistosaurid by Rieppel (1999a). This age assignment also refutes the longstanding interpretation that sauropterygians appeared in the Youjiang Basin during the Early Triassic, and shows instead that K. orientalis is almost synchronous with the Panxian marine reptile fauna. The Chinese record of sauropterygians shows that this group had dispersed over a large area and adapted to a diverse range of environments by the Anisian.

Basal, Amphibious Ichthyosaur Relative Found in Spathian Olenekian Triassic China

A basal ichthyosauriform with a short snout from the Lower Triassic of China

Authors:

Motani et al

Abstract:

The incompleteness of the fossil record obscures the origin of many of the more derived clades of vertebrates. One such group is the Ichthyopterygia, a clade of obligatory marine reptiles that appeared in the Early Triassic epoch, without any known intermediates. Here we describe a basal ichthyosauriform from the upper Lower Triassic (about 248 million years ago) of China, whose primitive skeleton indicates possible amphibious habits. It is smaller than ichthyopterygians and had unusually large flippers that probably allowed limited terrestrial locomotion. It also retained characteristics of terrestrial diapsid reptiles, including a short snout and body trunk. Unlike more-derived ichthyosauriforms, it was probably a suction feeder. The new species supports the sister-group relationships between ichthyosauriforms and Hupehsuchia, the two forming the Ichthyosauromorpha. Basal ichthyosauromorphs are known exclusively from south China, suggesting that the clade originated in the region, which formed a warm and humid tropical archipelago in the Early Triassic. The oldest unequivocal record of a sauropterygian is also from the same stratigraphic unit of the region.

A new Elasmosaurid Pleisosaur Found in Santonian Cretaceous Israel

A late Cretaceous elasmosaurid of the Tethys Sea margins (southern Negev, Israel), and its palaeogeographic reconstruction

Authors:

Rabinovich et al

Abstract:

Recent research on the late Cretaceous (Santonian), Menuha Formation of the southern Negev, Israel, has revealed several unconformities in its exposures, spatial changes in its lithofacies, agglomerations of its carbonate concretions and nodules at a variety of localities. At Menuha Ridge Site 20, portions of a new elasmosaurid skeleton were found within deposits of laminated bio-micritic muddy limestone with thin phosphatic layers. The sediments are rich in microfossils – foraminifera and ostracods preserved in the carbonate mud. Planktic foraminifera species (e.g. Dicarinella asymetrica, D. concavata, Sigalia decoratissima carpatica) appear as well as species indicative of opportunistic life strategies typical of a forming upwelling system in the region. Marine ostracods (e.g. Brachycythere angulata, Cythereis rosenfeldi evoluta) and many echinoid spines suggest an open marine environment. Using a multidisciplinary approach, we offer here a reconstruction of the micro-regional palaeogeography along a segment of the ancient shoreline of the Tethys Sea during the Santonian, and explain the environmental conditions under which the various fauna lived. This new elasmosaurid is examined in light of the above and compared with evidence from the adjacent areas along the margins of the southern Tethys Sea.