The earliest herbivorous marine reptile and its remarkable jaw apparatus
Authors:
Chun et al
Abstract:
Newly discovered fossils of the Middle Triassic reptile Atopodentatus unicus call for a radical reassessment of its feeding behavior. The skull displays a pronounced hammerhead shape that was hitherto unknown. The long, straight anterior edges of both upper and lower jaws were lined with batteries of chisel-shaped teeth, whereas the remaining parts of the jaw rami supported densely packed needle-shaped teeth forming a mesh. The evidence indicates a novel feeding mechanism wherein the chisel-shaped teeth were used to scrape algae off the substrate, and the plant matter that was loosened was filtered from the water column through the more posteriorly positioned tooth mesh. This is the oldest record of herbivory within marine reptiles.
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.
New Progress in the Study of Marine Reptiles from the Luoping Biota of Middle Triassic Anisian Period
Authors:
Wen et al
Abstract:
The Luoping Biota was discovered in 2007 by the Chengdu Center of China Geological Survey during 1:50000 regional mapping works at Dawazi Village, Luoxiong Town, 15 km southeast of Luoping City, Yunnan Province. The interval containing the Luoping biota is the middle to upper part of Member II of the Guanling Formation. The fossil assemblage of the Luoping biota is a mixture of marine animals, terrestrial plants and a few terrestrial animals. To date, more than ten fossil groups have been recovered, which include marine reptiles, fishes, arthropods, echinoderms, ammonites, bivalves, gastropods, lingulid brachiopods, foraminifers, and plants. The Luoping Biota is one of the most diverse Triassic marine fossil Lagerst?tten records in the world. The age of the Luoping biota is assigned to the Pelsonian Substage of the Middle Triassic Anisian Stage based on the index conodont Nicoraella Kockeli. Well-preserved, diverse marine reptiles are one of the highlights of the Luoping biota, including ichthyosaurs, sauropterygians, protorosaurs and archosauromorphs. Mesozoic is remarkable for marine reptiles, whose swimming modes, however, remain a topic of much controversy because of the absence of their tracks. Hundreds of seabed tracks found in Luoping Biota, which were assigned to Dikoposichnus luopingensis, provide new materials for the study of their locomotive mode. Besides, the macropredator Nothosaurus zhangi reported from Luoping Biota also supports the existence of the makers of Dikoposichnus luopingensis. The skull of Nothosaurus zhangi is the largest sauropterygian ever reported in Triassic. The occurrence of a different assemblage of marine reptiles as top predators in the food web indicates a well developed marine ecosystem, showing full rebuilding of the marine ecosystem after the mass extinction that happened about 250 million years ago.
‘Chasmatosaurus ultimus,’ a putative proterosuchid archosauriform from the Middle Triassic, is an indeterminate crown archosaur
Authors:
Liu et al
Abstract:
Proterosuchids represent the earliest known radiation of the highly diverse and important clade Archosauriformes (Gauthier et al., 1988; Nesbitt, 2011; Ezcurra et al., 2013). Huene (1908) erected Proterosuchidae as a monotypic Linnean family containing only Proterosuchus fergusi from the lowermost Triassic of South Africa, and several other species have been referred to this group in the subsequent century. However, phylogenetic analyses have provided only partial support for the existence of a diverse proterosuchid clade, and it is possible that some or even most putative proterosuchids form a series of outgroups to more derived archosauriforms rather than a monophyletic group (Ezcurra et al., 2010, 2013). Proterosuchids were historically classified alongside erythrosuchids in the Proterosuchia (e.g., Charig and Reig, 1970), but cladistic analyses (e.g., Benton, 1985; Gauthier et al., 1988; Gower and Sennikov, 1997; Ezcurra et al., 2010; Nesbitt, 2011) have uniformly found erythrosuchids to be phylogenetically closer to Archosauria (using a crown-group definition for the clade) than are any putative proterosuchids. Many of the species that have been assigned to Proterosuchidae require anatomical and taxonomic reevaluation (e.g., Ezcurra et al., 2010, 2013, 2014; Ezcurra, 2014), a research effort that is essential in order to clarify the phylogenetic relationships of the earliest archosauriforms and patterns of character evolution in taxa of this grade.
Following Proterosuchus, the next proterosuchid genera to be erected were Chasmatosaurus, established by Haughton (1924) for the new species C. vanhoepeni, and Elaphrosuchus, established by Broom (1946) for the new species E. rubidgei. A second species of Chasmatosaurus, C. alexanderi, was subsequently added (Hoffman, 1965). Chasmatosaurus vanhoepeni, C. alexanderi, and E. rubidgei were all based, like P. fergusi, on specimens from the Lower Triassic of South Africa, and more recently all of them have been suggested to represent subjective junior synonyms of P. fergusi (Welman, 1998). Occurrences of Chasmatosaurus have also been reported outside South Africa, including C. yuani (Young, 1936, 1963, 1978) from the Lower Triassic of China, Chasmatosaurus sp. from the Lower Triassic of India (Satsangi, 1964), and C. ultimus from the Middle Triassic of China (Young, 1958, 1964). The last of these species has the distinction of being one of only two putative proterosuchids from above the Lower–Middle Triassic boundary, the other being Sarmatosuchus otschevi from the Anisian of Russia (Gower and Sennikov, 1997, 2000; Ezcurra et al., 2013). However, the proterosuchid affinities of S. otschevi are questionable (Ezcurra et al., 2010, 2013), with S. otschevi having been recovered closer to erythrosuchids and archosaurs than to proterosuchids by Ezcurra et al. (2010). Thus, C. ultimus is the only generally accepted proterosuchid record younger than Early Triassic.
The holotype of C. ultimus is a partial skull including parts of the preorbital region preserved together with the anterior ends of the lower jaws, collected from the upper member of the Ermaying Formation of Shanxi Province in northern China, which is Anisian in age (Liu et al., 2013). This fragmentary specimen was originally assigned by Young (1958) to C. yuani, but later used by Young (1964) to erect C. ultimus based on differences in size and tooth curvature from the former species. Here we redescribe the specimen and show that ‘C. ultimus’ is not a proterosuchid but rather an indeterminate crown archosaur. An important implication of this revision is the absence of any confirmed record of proterosuchid archosauriforms from rocks of Middle Triassic age or younger.
Redox conditions in the end-Early Triassic Panthalassa
Authors:
Takahashi et al
Abstract:
This study focuses on an upper Lower Triassic (Spathian) to lowermost Middle Triassic (Anisian) section representing the central Panthalassic deep sea. Analysed organic carbon isotope ratio (δ13Corg) records from the section demonstrate that lower values in the Spathian increase by up to 6‰ at the Spathian–Anisian transition. This trend accords with the carbonate carbon isotope (δ13Ccarb) record from shallow-water carbonate sections. Most horizons during late Spathian–early Anisian show features of redox conditions of not fully oxic but dysoxic conditions, inferred from low Mn, U, V, Mo and euhedral pyrite-dominated occurrences. Conversely, in the end-Spathian black-coloured beds and underlying siliceous claystone beds, relatively higher concentrations of redox-sensitive elements such as U, V, Mo and abundant pyrite framboids are detected. As enrichment factors of redox-sensitive elements are not much higher than the typical anoxic–sulphidic trend and large pyrite framboids are found, these trends suggest suboxic rather than strong anoxic conditions. These oxygen-poor conditions coincide with carbon isotope minimum values at the late Spathian. At the same time, reducing seawater conditions have been also reported in from continental sections. These coincidences imply global environmental perturbations that may have been related to the delayed recovery of life after the end-Permian mass extinction.
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.
The osteology and systematic position of Dongusuchus efremovi Sennikov, 1988 from the Anisian (Middle Triassic) of Russia
Authors:
Niedźwiedzki et al
Abstract:
European Russia has yielded several fragmentary but potentially important archosauriform specimens from the Middle Triassic, but these have been only briefly described in the literature. One of these puzzling taxa is Dongusuchus efremovi Sennikov, 1988, described from the Donguz Svita. We present a redescription of Dongusuchus efremovi, which includes the first photographic atlas and thorough anatomical description of the holotype and referred specimens. This taxon is shown to be a gracile, probably fast-running species with elongate and slender limbs. A phylogenetic analysis recovers Dongusuchus efremovi as an early-diverging, non-archosaurian archosauriform. Previous work had suggested that this taxon was a ‘rauisuchid’. The gracile proportions of the femur and somewhat wedge-shaped head, however, are unusual for basal archosauriforms and are similar to the plesiomorphic state in crocodile and avian-line crown archosaurs. Several Early-Middle Triassic basal archosauriforms and early members of the crocodile and avian lineages were gracile with elongate, slender limbs. This suggests that the limb morphology of Dongusuchus efremovi may be plesiomorphic for Archosauria and proximal clades.
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.
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.
A new archosaur from the Manda beds (Anisian, Middle Triassic) of southern Tanzania and its implications for character state optimizations at Archosauria and Pseudosuchia
Authors:
Nesbitt et al
Abstract:
The presence of early pseudosuchians and avemetatarsalians in Anisian beds of Africa demonstrates that the archosaur radiation was well underway by the beginning of the Middle Triassic. The rapid radiation produced a variety of forms, but many of the unique, well-diagnosed Late Triassic clades (e.g., Aetosauria, Ornithosuchidae) lack diagnosable members from the Middle Triassic. Here, we introduce a new Middle Triassic archosaur, Nundasuchus songeaensis, gen. et sp. nov., with an unusual mix of apomorphic character states found within Pseudosuchia and just outside Archosauria. The holotype consists of partial skeleton, including representative postcranial elements and parts of the skull. We added Nundasuchus songeaensis, gen. et sp. nov., into the two most comprehensive early archosaur phylogenetic data sets available, and in both analyses the new taxon falls within Pseudosuchia. However, a number of plesiomorphic archosaurian character states (e.g., posterolaterally directed tuber of the calcaneum) optimize as local autapomorphies of the new taxon within Pseudosuchia in our analyses. Therefore, we tested alternative hypotheses of relationships for the new taxon by utilizing constraint trees. The analyses resulted in little change in the relationships and structure of other Triassic archosaur clades, but changed optimizations of certain character states and character support at the base of Pseudosuchia and Archosauria. Our analyses suggest that the complex evolution of character-state changes at the base of Archosauria is inhibiting our understanding of the relationships of early Pseudosuchia and, in turn, Archosauria.
Skeletal material from larger Eusauropterygia (Reptilia: Eosauropterygia) with nothosaurian and cymatosaurian affinities from the Lower Muschelkalk of Winterswijk, The Netherlands
Authors:
Voeten et al
Abstract:
Eusauropterygian elements from the Lower Muschelkalk (Vossenveld Formation) of Winterswijk, The Netherlands, comprising three mandibles and a selection of postcranial material, are described. The new mandibles correspond to crania larger than eusauropterygian cranial material previously known from this locality. The postcranial material represents a selection of isolated and associated material of comparably large size. Two of the mandibles conform to the morphology commonly recognized in Nothosaurus from the Lower Muschelkalk, but the third mandible accommodates five fangs per ramus in the symphyseal domain and exhibits a symphyseal ratio of 1.04, a condition not yet described for Eusauropterygia from the Vossenveld Formation. Body length for the animals represented by the finds was estimated through dimensional comparison with MB.R.27, a nearly complete skeleton from the lower Middle Muschelkalk locality of Rüdersdorf (Germany) assigned to Nothosaurus marchicus. Body length estimates for the individuals represented by the largest mandible and by a selection of associated postcranial material exceed 1,500 mm; approximately 50 % larger than the eusauropterygian taxa from Winterswijk described so far. Furthermore, certain morphological characters identified in one mandible and in the postcranial elements suggest a cymatosaurian affinity over a nothosaurian affinity. The present study indicates eusauropterygian diversity during the Lower Muschelkalk was greater than traditionally believed. This challenges the concept of a slow paced, gradual biotic response to the origination and expansion of the Muschelkalk Sea, which commenced only 5 million years after the Permian–Triassic mass extinction event.
The ‘Otter Sandstone River’ of the mid-Triassic and its vertebrate fauna
Author:
Hart
Abstract:
The Triassic succession of the East Devon coastline is a key component of the Jurassic Coast World Heritage Site. Within these strata are the sediments deposited by two major river systems: the Budleigh Salterton Pebble Beds and the Otter Sandstone Formation. The latter are significant as both a reservoir for the Dorset oilfields near Wareham and as a source of significant numbers of vertebrate fossils. The Otter Sandstone Formation, of Anisian (Middle Triassic) age, has a lower part formed of aeolian sands but these pass upwards into a series of river channel deposits. These river channels, which are best seen between the mouth of the River Otter and Ladram Bay, contain a series of classic features such as erosive channel bases, channel lag deposits, de-watering structures, calcified root systems (rhizoliths), reworked calcretes and (rare) overbank mudstones. The rivers that formed the various braided channel deposits flowed northwards or north-eastwards and there are at least 4 or 5 separate channel units within the Ladram Bay area. The Otter Sandstone Formation has yielded a great many rhynchosaur fragments and at least one partial skeleton. This juvenile individual appears to have fallen into one of the channels, resulting in the loss of its head (skull), as this was not recovered when the specimen was found by the author in 1990. This important specimen of Fodonyx spenceri (Benton, 1990) is housed in the Royal Albert Memorial Museum in Exeter.
Early Middle Triassic stromatolites from the Luoping area, Yunnan Province, Southwest China: Geobiologic features and environmental implications
Authors:
Luo et al
Abstract:
An early Middle Triassic stromatolite deposit is documented from the Guanling Formation of the Luoping area, Yunnan, SW China. The Luoping stromatolite shows five types of constructional microbial forms in various magnifications: 1) typical stratified columnar structures, up to 20 cm high, with crinkled laminae. Dark coloured laminae, 1 mm thick, are composed of upright filamentous tubes, averagely 29.4 μm in diameter, showing a vertical growth fabric. 2) Laminoid fenestrae, 0.5–1 mm wide, and 3) prostrate filaments, which are reflected by strong fluorescence in sharp contrast to dolomite cement in fluorescent images. 4) Rod-like aggregates, 4.6–18 μm in diameter, composed of minute dolomite rhombs, are very common in stromatolitic laminae; they resemble present-day cyanobacterial trichome, and thus may represent putative fossilized cyanobacteria. 5) Moreover, small pits, coccoid-like spheroids, calcified biofilms, and fibrous structures are also common in stromatolitic laminae. The last two may represent calcified extracellular polymeric substances (EPS) that contributed to the development and lithification of stromatolites. Authigenic quartz grains are common and may also have involved biological processes in stromatolite formation. Of these microbial functional-groups driving accretion and lithification processes of stromatolite documented in literature, both lithified cyanobacteria/oxygenic phototrophs and possible sulfate-reducing bacteria (SRB), which induced microbial formation of dolomite and contributed to the accretion of the Luoping stromatolite, are suggestive of biogenic origin. The Luoping stromatolite differs from the Permian–Triassic boundary microbialites (PTBMs) in having abundant filamentous structures and growing in an oxic marine environment. Both sedimentary facies analysis and abundant fossilized cyanobacteria may indicate proliferation of oxygenic phototrophs in a normal, oxic habitat during the middle Anisian (early Middle Triassic), a period when hospitable environments, coupled with biotic diversification, prevailed in South China and set an agenda for the full recovery of marine ecosystems in middle–late Anisian. However, the post-extinction stromatolites and other anachronistic facies are not necessarily indicative of anoxic or oxic conditions, and their environmental settings are much more complex than previously thought.
Osteohistology of the Early Triassic ichthyopterygian reptile Utatsusaurus hataii: Implications for early ichthyosaur biology
Authors:
Nakajima et al
Abstract:
Ichthyosaurs were highly adapted to a marine lifestyle, as shown by their fish-like body shape and their assumed active swimming abilities and high metabolic rates. However, the processes of adaptation to an aquatic life in the early stages of this lineage remain poorly understood. Here, we present the first osteohistological data concerning the most basal ichthyopterygian yet known, Utatsusaurus hataii, from the Lower Triassic of Japan. The cancellous bone structure suggests adaptation to active swimming in an open marine environment. Moreover, the possible occurrence of rapidly deposited bone tissue, in a fibrolamellar complex, suggests a higher metabolic rate than in modern poikilothermic reptiles, and therefore a trend toward homeothermy. This basal ichthyosaur, with its elongate body, was already more adapted to an aquatic lifestyle than expected from its morphology, and the process of adaptation to a marine lifestyle was already well advanced by the Early Triassic.
New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation
Authors:
Butler et al
Abstract:
Background
The origin and early radiation of archosaurs and closely related taxa (Archosauriformes) during the Triassic was a critical event in the evolutionary history of tetrapods. This radiation led to the dinosaur-dominated ecosystems of the Jurassic and Cretaceous, and the high present-day archosaur diversity that includes around 10,000 bird and crocodylian species. The timing and dynamics of this evolutionary radiation are currently obscured by the poorly constrained phylogenetic positions of several key early archosauriform taxa, including several species from the Middle Triassic of Argentina (Gracilisuchus stipanicicorum) and China (Turfanosuchus dabanensis, Yonghesuchus sangbiensis). These species act as unstable 'wildcards' in morphological phylogenetic analyses, reducing phylogenetic resolution.
Results
We present new anatomical data for the type specimens of G. stipanicicorum, T. dabanensis, and Y. sangbiensis, and carry out a new morphological phylogenetic analysis of early archosaur relationships. Our results indicate that these three previously enigmatic taxa form a well-supported clade of Middle Triassic archosaurs that we refer to as Gracilisuchidae. Gracilisuchidae is placed basally within Suchia, among the pseudosuchian (crocodile-line) archosaurs. The approximately contemporaneous and morphologically similar G. stipanicicorum and Y. sangbiensis may be sister taxa within Gracilisuchidae.
Conclusions
Our results provide increased resolution of the previously poorly constrained relationships of early archosaurs, with increased levels of phylogenetic support for several key early pseudosuchian clades. Moreover, they falsify previous hypotheses suggesting that T. dabanensis and Y. sangbiensis are not members of the archosaur crown group. The recognition of Gracilisuchidae provides further support for a rapid phylogenetic diversification of crown archosaurs by the Middle Triassic. The disjunct distribution of the gracilisuchid clade in China and Argentina demonstrates that early archosaurs were distributed over much or all of Pangaea although they may have initially been relatively rare members of faunal assemblages.
Wildfires in the late Palaeozoic and Mesozoic of the Southern Alps—the Anisian and Ladinian (Mid Triassic) of the Dolomites (Northern Italy)
Authors:
Uhl et al
Abstract:
Based on anatomical studies of fossil charcoal fragments the first evidence for palaeo-wildfires is presented for the Anisian and Ladinian of the Dolomites (Northern Italy). These charcoals are from the localities Kühwiesenkopf/Monte Prà della Vacca (middle-upper Pelsonian, upper Anisian) and Ritberg/Ju Rit (Longobardian, upper Ladinian), and they help to fill a gap in our current scientific knowledge on the fossil record of Triassic wildfires worldwide. Charcoal reflectance values from Kühwiesenkopf are surprisingly high, indicating a palaeo-wildfire temperature of approximately 650 °C.
A potential record of a procolophonid parareptile from the Triassic of the Iberian Peninsula
Authors:
Fortuny et al
Abstract:
Cranial and postcranial remains from the Middle Triassic of the NorthEastern part of the Iberian Peninsula are reported and tentatively assigned to Procolophonidae. The finding is the first occurrence of a procolophonid parareptile in the Iberian Peninsula, representing the southernmost record of the group in Europe. The fossil bearing locality is dated as Anisian (Middle Triassic) and includes three tooth-bearing bones, two cranial bone fragments and one interclavicle. The mandible described herein includes nine teeth. No cusps or complete crowns are preserved, but sections of the teeth are available. The three anterior teeth progressively decrease in size from front to back, while the teeth from the fourth to the eighth position present the opposite trend. The last tooth (the ninth) is clearly reduced in comparison to the previous ones. A close relationship with Anomoiodon-Kapes is suggested, however, more material is required in order to assess the exact taxonomical determination of the Iberian remains. This finding is expected to shed some light on the geographical distribution of procolophonines.
The monophyly of Euparkeriidae (Reptilia: Archosauriformes) and the origins of Archosauria: a revision of Dorosuchus neoetus from the Mid-Triassic of Russia
Authors:
Sookias et al
Abstract:
Euparkeria capensis is resolved as the sister taxon to Archosauria in many cladistic phylogenies and provides a key outgroup which may approximate the ancestral archosaur morphology. Several other taxa have been referred to the family Euparkeriidae, but the monophyly of this taxon remains doubtful and largely untested. To test this monophyly, the archosauriform and putative euparkeriid Dorosuchus neoetus from the Mid-Triassic of Russia is re-examined in the light of recent work on the evolution of stem archosaurs. Dorosuchus neoetus is found to possess a number of morphological features that place it close to Archosauria, including a sigmoidal femur with a clear attachment region for the m. caudifemoralis musculature, but no unambiguous archosaurian apomorphies. Dorosuchus neoetus is included for the first time in a numerical cladistic analysis and is recovered as the sole sister taxon to Archosauria + Phytosauria. A monophyletic Euparkeriidae including D. neoetus and E. capensis is slightly less parsimonious. In addition, a mandible and pterygoid that were previously referred to D. neoetus subsequent to the original description of the species are also included separately within the phylogenetic analysis and are recovered within Archosauria, possibly raising questions as to their correct taxonomic referral. However, this phylogenetic placement is based primarily on the absence of palatal teeth, but the presence or absence of palatal teeth exhibits considerable homoplasy within Archosauriformes. Based on other aspects of their morphology, we do not reject the referral of these elements to D. neoetus.
A new capitosauroid temnospondyl from the Middle Triassic upper Fremouw Formation of Antarctica
Authors:
Sidor et al
Abstract:
We describe a new capitosauroid temnospondyl, Antarctosuchus polyodon, gen. et sp. nov., on the basis of a large and relatively complete skull from the upper Fremouw Formation of Antarctica. The new species is characterized by its possession of numerous, extremely small maxillary, palatine, and ectopterygoid teeth, a dental pattern that suggests specialization on small prey items, possibly invertebrates. The taxon is also characterized by a parachoanal tooth row that extends far posterior to the choana and occipital condyles set close to the midline. A combination of features, including a flat skull and low occiput together with well-developed sensory canals, suggests an aquatic lifestyle. We address the phylogenetic relationships of Antarctosuchus by adding it to a recent cladistic analysis of Capitosauria. The revised data set includes 27 taxa and 53 characters. The results of this analysis place Antarctosuchus within a clade of derived Triassic stereospondyls as the sister taxon to Paracyclotosaurus crookshanki from the Triassic Denwai Formation of India. To date, the upper Fremouw Formation has yielded two endemic temnospondyl species (viz., Kryostega collinsoni and Antarctosuchus polyodon), although indeterminate remains referred to benthosuchids and a cranial fragment assigned to Parotosuchus sp. have also been noted. In contrast to the broadly distributed therapsid taxa recognized from the Middle Triassic of Antarctica (e.g., Cynognathus, Diademodon), the temnospondyl fauna suggests more limited interchange with other coeval southern Pangean basins (e.g., Karoo, Luangwa, Ruhuhu, Waterberg).
A well preserved skull of Cymatosaurus (Reptilia: Sauropterygia) from the uppermost Buntsandstein (Middle Triassic) of Germany
Author:
Maisch
Abstract:
A sauropterygian skull from the uppermost Buntsandstein (earliest Anisian, uppermost Röt-Formation, Cölestinschichten) of Wogau (Thuringia, eastern Germany) is described in detail and assigned to a new species of Cymatosaurus, Cymatosaurus erikae. Cymatosaurus erikae n. sp. differs from all other species of the genus by a unique combination of dental and cranial features, including nasals that do not reach the external naris or the anterior margin of the orbit, frontals that do not enter the orbital margin and closely approach but do not enter the temporal fenestra, at least two maxillary teeth anterior to the fangs, a long parietal that extends up to the orbit and narrows posteriorly without forming a sagittal crest, unfused vomers, narrow and elongate palatines, and inclined quadrates and quadrate condyles. The new specimen shows a completely closed palate as in nothosaurids, but retains an open occiput. A small lacrimal (recorded here for the first time in Cymatosaurus) is probably present. These features are plesiomorphic for sauropterygians. This combination of features makes it conceivable that Cymatosaurus might actually be a stem-nothosaur rather than a stem plesiosaur, as previously suggested. A phylogenetic analysis of Cymatosaurus species indicates that C. erikae is the sister-taxon of C. latifrons and C. fridericianus. Cymatosaurus gracilis (Schrammen, 1899) is reconsidered and re-established as a valid species of the genus, contrary to previous suggestions.
