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A re-evaluation of the historical 'dinosaur' remains from the Middle-Upper Triassic of Poland
Abstract and Figures
The so-called historical Polish discoveries of Triassic ‘dinosaurs’ have been repeatedly cited in papers and popular science books. Here, we re-evaluate each historical and purported Triassic dinosaur find from Poland. Additionaly, we describe several supposed ‘dinosaur’ bones collected by Polish geologists but only briefly mentioned: in regional geological journals, on collection labels, or in field notes. We attempt to assign all investigated specimens to the least inclusive taxon possible. Our revision indicates that part of this material represents non-dinosaur archosauromorph taxa. Most of the analysed specimens are fragmentary bones or isolated teeth and are indistinguishable from skeletal elements described from other well-known Triassic archosauromorph taxa. We conclude that fossils of dinosauriforms are present in the Upper Triassic of Silesia and Holy Cross Mountains. New analysis of Velocipes guerichi von Huene, 1932 holotype specimen from Kocury shows that it is the proximal part of fibula of a medium-sized theropod (or even neotheropod). Formally undescribed part of dinosauriform limb bone from the Holy Cross Mountains and V. guerichi from Silesia are the only identifiable dinosauromorph skeletal remains recognised in the Polish Triassic discovered prior to the description of Silesaurus opolensis Dzik, 2003 from the Upper Carnian of Krasiejów.
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... The recent excavation site is located east of Kocury village (Skawinśki et al., 2017). It lies in south-western Poland, in the Silesia region, 40 km north-east of Opole and 6 km north of Dobrodzień (Fig. 1A). ...
... The portion of the conglomerate preserved at the proximal tip of the Velocipes guerichi specimen GPIM UH no. 252 collected there in the 19th century (von Huene, 1932;Skawinśki et al., 2017) is similar to that exposed in Kocury during our excavations. Hence, it is plausible that the specimen was collected from the strata similar to these described herein, likely from one of the nearby quarries. ...
... Remarks-The holotype of Velocipes guerichi von Huene, 1932, an incomplete left fibula (GPIM UH No. 252; Fig. 4), was the first bone collected from the Kocury locality in the 19th Century (von Huene, 1932;Skawinśki et al., 2017). It was considered to be a 'coelurosaurian' or halticosaurid theropod (von Huene, 1932Huene, , 1956, podekosaurid (Carroll, 1988), a neotheropod congeneric with Liliensternus (Welles, 1984), an indeterminate ceratosaurian (Tykoski and Rowe, 2004;Weishampel et al., 2004), or an indeterminate vertebrate (Rauhut and Hungerbühler, 1998). ...
Since 1990, several localities within the Keuper (upper Middle to Upper Triassic) strata in southern Poland have yielded remains of numerous terrestrial vertebrate species. Here we report a new Upper Triassic vertebrate assemblage from the rediscovered Kocury locality. An incomplete theropod dinosaur fibula named Velocipes guerichi described in 1932 was found there. The site was then forgotten and not explored until our excavations began in 2012, that yielded material of a lungfish, a proterochersid turtle, and a new typothoracin aetosaur Kocurypelta silvestris gen. et sp. nov. The new taxon is characterized by autapomorphies of the maxilla: an elongated edentulous posterior portion longer than 80% of the posterior maxillary process, a short medial shelf restricted to the posterior portion of the bone, an anteriorly unroofed maxillary accessory cavity, and lack of a distinct groove for choanal recess on the anteromedial surface of the bone. These new finds improve our knowledge on the vertebrate diversity of the Germanic Basin in the Late Triassic, evidencing the presence of yet unrecognized taxa. Additionally, the partial cranial aetosaur material emphasizes the issues with the aetosaurian taxonomy that is focused mostly on the osteoderm morphology
... There have been a variety of theropod and sauropodomorph taxa described from other Triassic sites in southwestern Poland, but few are still considered valid (see the extensive discussion in Skawiński et al. 2016). Velocipes guerichi Huene (1932, GPIM UH No. 252) probably represents the proximal end of a fibula belonging to an early theropod from a clay pit in the 'Lisów Breccia' (Middle Triassic to Upper Triassic) (Fig. 19) near Kocury, and an unnumbered proximal end of a fibula from the Keuper Group (Norian to Rhaetian) near Ostrowiec Świętokrzyski is referred to Dinosauriformes (Skawiński et al. 2016). ...
... There have been a variety of theropod and sauropodomorph taxa described from other Triassic sites in southwestern Poland, but few are still considered valid (see the extensive discussion in Skawiński et al. 2016). Velocipes guerichi Huene (1932, GPIM UH No. 252) probably represents the proximal end of a fibula belonging to an early theropod from a clay pit in the 'Lisów Breccia' (Middle Triassic to Upper Triassic) (Fig. 19) near Kocury, and an unnumbered proximal end of a fibula from the Keuper Group (Norian to Rhaetian) near Ostrowiec Świętokrzyski is referred to Dinosauriformes (Skawiński et al. 2016). Additionally, the taxon Smok wawelski Niedźwiedzki et al. (2012, ZPAL V.33/15) is known from the Lisowice (Lipie Śląskie) clay pit and at Marciszów in southern Poland (Dzik et al. 2008, Niedźwiedzki et al. 2012, Niedźwiedzki and Budziszewska-Karwowska 2018. ...
... In some cases, the presence of dinosauromorphs in Triassic assemblages hinges on such fragmentary fossils that often end up being determined to be other kinds of reptiles. For example, certain purported dinosaur specimens from the Middle-Upper Triassic of Poland represent tanystropheid archosauromorophs (Skawiński et al. 2016) and the purported dinosaur from the Upper Triassic Popo Agie Formation of Wyoming Poposaurus gracilis is actually a non-loricatan pseudosuchian (Gauthier et al 2011, Nesbitt 2011. Using discrete apomorphies to identify fragmentary specimens like those from PEFO reported here allows for unambiguous determinations of the presence of certain clades in their stratigraphic context. ...
Dinosauromorph specimens from Petrified Forest National Park have been recovered from four major collecting efforts since 1982, including the most recent paleontological inventory of new park lands acquired in 2011. Additionally, an emphasis on understanding the stepwise acquisition of character traits along the dinosaurian lineage has helped identify previously collected specimens in museum collections. Here we briefly describe and use apomorphies to identify 32 additional dinosauromorph specimens found at Petrified Forest National Park, bringing the total number of dinosauromorph specimens presently known from the park to 50, a 600% increase since the year 2000. These specimens are all Norian in age and come from the Blue Mesa Member, Sonsela Member, and Petrified Forest Member of the Chinle Formation. These include the proximal end of a tibia that represents the oldest unambiguous dinosaur specimen from the Chinle Formation. We then contextualize these specimens with the dinosauromorph assemblages from the Norian of Utah, Colorado, New Mexico, and Texas, as well as the Carnian and Norian dinosauromorph assemblages from South America, Africa, and Europe. Despite increased sampling we still find no evidence for sauropodomorph and ornithischian dinosaurs in Western North America. An increase in sampling, combined with the use of apomorphies to identify collected specimens, will continue to improve the global dinosauromorph fossil record that can be used to answer questions on biochronology and the evolutionary history of the avian lineage.
... conspicuus, T. antiquus, and T. haasi) or a single incomplete specimen (T. meridensis, T. fossai) (Meyer, 1855;Huene, 1905Huene, , 1907Huene, -1908Wild, 1973Wild, , 1980aRieppel, 2001;Fraser and Rieppel, 2006;Sennikov, 2011;Skawiński et al., 2017). Additionally, isolated remains from Europe, the Middle East, Asia, and North America have been attributed to the genus but have not been determined to the species level (Vickers-Rich et al., 1999;Rieppel, 2001;Dalla Vecchia and Avanzini, 2002;Dalla Vecchia, 2005;Li, 2007;Sues and Olsen, 2015). ...
... Currently, this specimen is considered an otherwise indeterminable caudal vertebra of a theropod dinosaur, and the taxon "Tanystropheus posthumus" is considered a nomen dubium (Rauhut and Hungerbühler, 2000). The T. antiquus material from the Gogolin beds was recently preliminarily revised, and these specimens are considered to be of early Anisian and possibly latest Olenekian age (Skawiński et al., 2017). ...
... Additionally, among the material discussed, specimens previously assigned to "Thecodontosaurus latespinatus", "Thecodontosaurus primus", and "Procerosaurus cruralis" were also considered to very likely belong to the genus Tanystropheus (Huene, 1931; see also the synonymy lists for T. conspicuus and T. antiquus by Wild, 1973, p. 148-149, 151). However, the assignment of "Thecodontosaurus primus" to the genus was recently questioned, and a detailed revision of this material is required to establish its affinities (Skawiński et al., 2017). ...
Tanystropheus represents one of the most characteristic genera of Triassic reptiles and is typified by easily recognizable, hyperelongate cervical vertebrae. First described in 1852, isolated cervical vertebrae and other remains have been referred to the genus and various species have been erected and rejected based on this material. This has resulted in a complicated and convoluted taxonomic history of the genus and confusion as to the validity of species and the referral of specimens. With the exception of the well-represented T. longobardicus, the five other species of Tanystropheus are known from isolated elements or a single, partial specimen. Here, we provide a complete overview of the taxonomic history and a revision of the genus based on first hand observations of the type material of most of the species. From this, we conclude that T. conspicuus and T. haasi should be considered nomina dubia and that T. meridensis constitutes a junior synonym to T. longobardicus. Furthermore, T. longobardicus can be subdivided into two discrete morphotypes that might represent separate species. However, a more detailed study is required to test this hypothesis. Finally, T. fossai is considered distinctly different from the other Tanystropheus taxa and is therefore referred to a separate genus, Sclerostropheus.
... Especially, findings of large isolated teeth of predators are not so rare as cranial or postcranial bones. Many discoveries of isolated large serrated teeth are also known from the Middle-Upper Triassic deposits of southern Poland (Kuhn 1965;Surmik and Brachaniec 2013;Skawiński et al. 2017) and among them is one of the first published remains of an archosaur from Triassic of Poland ("Megalosaurus" cloacinus Quenstedt, 1858) which represents a well-serrated and mediolaterally compressed large predator tooth (Roemer 1870: pl. 15: 5; see also Skawiński et al. 2017). ...
... Many discoveries of isolated large serrated teeth are also known from the Middle-Upper Triassic deposits of southern Poland (Kuhn 1965;Surmik and Brachaniec 2013;Skawiński et al. 2017) and among them is one of the first published remains of an archosaur from Triassic of Poland ("Megalosaurus" cloacinus Quenstedt, 1858) which represents a well-serrated and mediolaterally compressed large predator tooth (Roemer 1870: pl. 15: 5; see also Skawiński et al. 2017). ...
... A recently published results (Sulej et al. 2018, in press) suggest strong similarity of the Woźniki site fauna to that from the Krasiejów site (see Dzik andSulej 2007, 2016) assigned to the early Adamanian (late Carnian in age) land-vertebrate faunachron (Lucas 2010(Lucas , 2015 of a spinicaudatan (Laxitextella), a capitosaur (Cyclotosaurus sp.), a diapsids Ozimek sp., a silesaurid dinosauriform, single-rooted postcanine teeth of a non-mammaliaform eucynodont, rich phytosaur remains (Phytosauria indet.), and the lack of more advanced dinosaurian taxa, which are present in the middle-late Norian/earliest Rhaetian of Poland (see Dzik et al. 2008;Sulej et al. 2012;Niedźwiedzki et al. 2012Niedźwiedzki et al. , 2014Skawiński et al. 2017). The discovery of Smok remains at Marciszów is also significant because it is the second example of the co-occurrence of this genus with a large and tooth-less dicynodont and a unique record of gnawed bones (Budziszewska-Karwowska et al. 2010;Niedźwiedzki et al. 2011Niedźwiedzki et al. , 2012. ...
Two isolated teeth, a dorsal vertebra, fragments of a humerus and femur, a fragmentary pubic “boot” and part of an ischium shaft, identified here as belonging to a large predatory archosaur were discovered in the Upper Triassic site at Marciszów near Zawiercie (southern Poland). Comparisons of the new fossils from Marciszów with the dorsal vertebrae, pubic “boot”, ischium and femur of the theropod-like Smok wawelski from Lisowice (Silesia) reveal that the two taxa are very similar. Nevertheless, due to the lack of more diagnostic elements (e.g., braincase or cranial elements), we prefer to consider all described specimens from Marciszów as Smok sp. Smok sp. shares a low mound-like, anterior trochanter with trochanteric shelf on the femur, a massive pubic “boot” with a distinct depression (= bevelled area), and a transversely lenticular ischium shaft in cross-section with S. wawelski. Some observed characters of the dorsal vertebra (e.g., lack of some lamina, shape and position of zygapophyses), however, are different from S. wawelski and may also suggest that the new findings represent a second species of the genus in the Upper Triassic of Poland. The discovery of Smok sp. at Marciszów is significant because it is the second example of the co-occurrence of this genus with: (i) bones of a large dicynodont; and (ii) record of gnawed tetrapod bones. The discovery of Smok sp. and the lack of significant morphologic divergence from S. wawelski suggest that this taxon is the only large-bodied predator currently known from the Upper Triassic of Poland. This new evidence expands the record of the genus and contributes, in some measure, to our knowledge of the stratigraphical distribution of large predatory archosaurs from the Polish Upper Triassic bone-bearing levels.
... Horizons with numerous remains of vertebrates also occur in the Upper Triassic of the Silesia region (e.g., Krasiejów, Lisowice, Poręba, Woźniki). However, Upper Triassic deposits were formed in freshwater or terrestrial environments and they do not contain marine fish (e.g., Saurichthys, Colobodus, Gyrolepis) or bivalves (Plagiostoma, Entolium) which occur in the studied exposure near Kalety (compare, e.g., [25][26][27]. The Tarnowice Beds and Wilkowice Beds are formed by limestones. ...
The new exposure of the Upper Muschelkalk clays and dolomites located south of Kalety (Tarnogórski District, Silesia, Poland) provided numerous remains of vertebrates represented by teeth, scales, long bones, and coprolites. Despite the influence of hydrothermal processes leading to dolomitization and Zn-Pb deposit formation, the preservation of fossil remains is good. The taxonomic diversity and accumulation of vertebrate debris in the dolomite are similar to other “bone beds” from the Muschelkalk and the Lower Keuper units. The SEM-EDS, EMP-WDS, and XRD analyses confirm that the examined remains consist of hydroxylapatite containing carbonate ions. Most vertebrate teeth as well as some bone fragments show zoning in the BSE imaging. In tooth cross-sections, three or two zones are preserved: (I) the outermost zone, associated with diagenetic mineralization of enameloid apatite, (II) a intermediate zone (orthodentine), and (III) the most porous internal zone (osteodentine). Decreasing P, Ca, Sr in the composition of the apatite which forms successive zones, is visible from the most external to the central part. Selective diagenetic substitution and adsorption of some elements by apatite crystals can allow recognition of the genetic origin of highly damaged or transported fragments scattered in the sedimentary layers. The chemical behavior of bioapatite, from deposition to digenesis, shows its useful role for identification of the formation process and potential, younger changes (e.g., hydrothermal overprint). The X-ray diffraction data, particularly cell parameters “a” and “c”, can determine the degree of crystallinity and/or diagenesis. Moreover, correlation between some elements/ions (e.g., Sr, Ba, Ca, Mg, F, OH) can be helpful for the identification of the fossil type, especially if the bones are small and incomplete.
... This group is characterised by their extremely elongated necks (Spiekman et al., 2020a;Spiekman et al., 2021). Tanystropheids already inhabited the Germanic Basin in the early Anisian as is evidenced by finds from the Upper Buntsandstein of the Black Forest in Germany (Fraser & Rieppel, 2006) and Lower Muschelkalk localities in Upper Silesia (Skawiński et al., 2017;Spiekman & Scheyer, 2019) and Winterswijk (Wild & Oosterink, 1984;. The Buntstandstein material is represented by poorly preserved, partially articulated specimens of Amotosaurus rotfeldensis, whereas the Lower Muschelkalk specimens comprise isolated postcranial elements, mostly cervical vertebrae, which have been referred to 'Tanystropheus antiquus' (Fraser & Rieppel, 2006;Spiekman & Scheyer, 2019). ...
In the aftermath of the Permo-Triassic mass extinction event, several reptile lineages radiated to form major components of marine faunas during the entire Mesozoic. The Lower Muschelkalk, which was deposited within a shallow inland sea in the Germanic Basin during the Middle Triassic, is one of the most important regions for understanding the early evolution of Mesozoic marine reptiles. Here, we present a new specimen from the Lower Muschelkalk of Winterswijk in the Netherlands, comprising an isolated left dentary that is morphologically distinct from any well-known Triassic vertebrate. We provide a detailed description of the jaw and the teeth using histological and micro-computed tomographic analyses. The anterior teeth are fang-like and curved, whereas the posterior teeth are wider and triangular-shaped. Tooth implantation is thecodont and teeth are ankylosed to the base of the alveolus. Replacement teeth are developed directly lingual to the functional teeth, starting with the formation of a resorption cavity on the dorsal surface of the alveolar margin. The replacement pattern cannot be observed in detail but is regular in the posterior part of the dentary with each tooth being alternated with an empty alveolus. The specimen can likely be assigned to Eosauropterygia based on its jaw morphology and dental morphology and replacement pattern, and it is remarkably similar to maxillae referred to the enigmatic Lamprosauroides goepperti from the Lower Muschelkalk of Poland. The dentary from Winterswijk lacks enlarged, ‘alveolarised’ crypts and corresponding distinct dental lamina foramina (DLFs) for the replacement teeth, a configuration that is typical of Sauropterygia, but which was likely not omnipresent in this clade. The specimen also exhibits loosely folded plicidentine at the roots of the teeth, likely representing the first identification of this feature in Sauropterygia.
... The material currently known for Tanystropheus "conspicuus" is undiagnostic at the species level and this taxon is therefore currently considered a nomen dubium (Spiekman & Scheyer, 2019). "Tanystropheus antiquus" is currently insufficiently defined, since much of the type material that was considered to have been lost was recently rediscovered and is in need of revision (Skawi nski et al., 2017;Spiekman & Scheyer, 2019). Therefore, both analyses outlined above (one round excluding ratio characters and treating all characters as unordered, and one round including ratio and ordered characters) were performed once including all 42 OTUs, and once excluding Czatkowiella harae, Tanystropheus "conspicuus", and "Tanystropheus antiquus" a priori. ...
The historical clade “Protorosauria” represents an important group of archosauromorph reptiles that had a wide geographic distribution between the Late Permian and Late Triassic. “Protorosaurs” are characterized by their long necks, which are epitomized in the genus Tanystropheus and in Dinocephalosaurus orientalis . Recent phylogenetic analyses have indicated that “Protorosauria” is a polyphyletic clade, but the exact relationships of the various “protorosaur” taxa within the archosauromorph lineage is currently uncertain. Several taxa, although represented by relatively complete material, have previously not been assessed phylogenetically. We present a new phylogenetic hypothesis that comprises a wide range of archosauromorphs, including the most exhaustive sample of “protorosaurs” to date and several “protorosaur” taxa from the eastern Tethys margin that have not been included in any previous analysis. The polyphyly of “Protorosauria” is confirmed and therefore we suggest the usage of this term should be abandoned. Tanystropheidae is recovered as a monophyletic group and the Chinese taxa Dinocephalosaurus orientalis and Pectodens zhenyuensis form a new archosauromorph clade, Dinocephalosauridae, which is closely related to Tanystropheidae. The well-known crocopod and former “protorosaur” Prolacerta broomi is considerably less closely related to Archosauriformes than was previously considered.
... Teeth belonging to morphotype 4 show similarities to the dentition described as probably belonging to a small, aquatic, tanystropheid protorosaurian, such as Tanytrachelos (Heckert, 2004). Of particular note are the teeth of an early theropod dinosaur (ArM16; Heckert et al., 2012) and morphotypes showing similarities to basal crocodylomorphs (ArM10) and basal sauropodomorphs (ArM13), that could be one of the earliest representatives of these groups in the Polish fossil record, in the case of theropoda representatives from the Late Triassic of Poland, previously described from two other localities Skawiński et al., 2017). Some of the other specimens are similar in dentition to morphotypes, which were described by Heckert (2004), as the teeth of early ornithischians (ArM12, ArM13). ...
... In recent years, numerous vertebrate and invertebrate remains have been found in Upper Triassic continental facies of Upper Silesia (southern Poland), including reptiles, amphibians, fish, bivalves, and mammals (e.g., Dzik et al., 2000;Dzik, 2001;Sulej, 2002;Dzik and Sulej, 2007;Niedźwiedzki and Sulej, 2008;Świło et al., 2014;Lucas, 2015, Skawiński et al., 2017Bodzioch, 2018a, 2018b;Konietzko-Meier et al., 2018;Sulej et al., 2018). These findings are significant in the understanding of animal evolution, especially as the late Triassic marks the dawn of dinosaurs, pterosaurs, and mammals ( Benton et al., 2014). ...
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The numerous discoveries of disintegrated skeletons of large terrestrial vertebrates within several thin levels of the Upper Silesian Keuper initiated broad investigations into the palaeoenvironment and age of the bone-bearing sediments. Despite years of research, the depositional history of the Upper Triassic continental succession and its controlling factors are still poorly recognized. This paper reconstructs the depositional evolution of the Upper Triassic strata in Upper Silesia, Poland, discusses the tectonic and climatic control on deposition, and identifies the sediment provenance. Detailed sedimentological analysis enabled the recognition of three major palaeoenvironments: (1) playa; (2) distal floodplain featured by gilgai micromorphology; (3) fluvial system (sand-dominated meandering, sand- and gravel-dominated braided, and potentially anastomosing river system). The transition from one palaeoenvironment into another reflects climatic changes throughout the late Triassic. The Carnian interval is dominated by gypsum-rich playa mudstones deposited under hot and arid conditions, with only one wet episode recorded as meandering river sandstones (the so-called Carnian Pluvial Event). In contrast, Norian sedimentation was controlled by strong seasonal climatic variations, which is reflected in alternating palaeosol horizons (vertisols and calcisols), thin claystone beds (small water-pond deposits), and conglomerates (rapid flood events). This facies assemblage was formed in a relatively stable floodplain which became the main habitat of numerous vertebrate organisms. The Rhaetian is represented by a gravel-dominated braided river system developed in response to significant climate humidification, with tectonic controls on flow direction. Clast types from Norian and Rhaetian conglomerates revealed that the studied area was fed from the south and south west by the San River and Moesian Massifs. Geochemical analysis of Norian palaeosol horizons suggests mean annual precipitation of ~ 720 mm/yr in agreement with the palaeoclimatic reconstructions for the area, pointing to seasonal sub-humid to semi-arid climate conditions.
... The discovery of S. opolensis helped to identify other problematic dinosauriform remains from the Middle and Upper Triassic of Pangea (i.e. Ezcurra 2006;Nesbitt et al. 2007Nesbitt et al. , 2010Nesbitt et al. , 2013Nesbitt et al. , 2017Kammerer et al. 2012;Niedźwiedzki et al. 2016; Barrett et al. 2015;Skawiński et al. 2017), and demonstrated that the dinosaur lineage appeared earlier than had previously been thought (Brusatte et al. 2011;Niedźwiedzki et al. 2013;Cabreira et al. 2016). ...
Silesaurus opolensis Dzik, 2003 from the Late Triassic (late Carnian) of Poland is a key taxon for understanding the evolution of early dinosaurs. High intraspecific variation observed in the S. opolensis braincase brings caution in taxonomic and diversity studies of early dinosauromorphs. The external and internal osteology of three almost complete braincases of S. opolensis show that this taxon shares several similarities with other early dinosauriforms, which supports a close relationship among these forms. However, the paroccipital processes of S. opolensis are directed ventrally like in birds, reaching the level of the ventral margin of the basioccipital condyle. In dinosauromorphs, these processes usually have an almost horizontal orientation (presumed to be the plesiomorphic condition). Modifications observed in birds and S. opolensis have resulted in the dorsoventral expansion of M. complexus and M. depressor mandibulae, which occupy the dorsolateral part of the posterior side of the skull. In adult birds, these muscles act strongly on the initial upstroke of the head during drinking. Therefore, the inferred condition of these muscles in S. opolensis may imply that Silesauridae evolved toward bird-like feeding behaviour.
Dicynodont therapsids are prominent elements of Triassic continental faunas, but the date of their demise is controversial, linked either to end-Carnian faunal turnover or to end-Triassic mass extinction. The second timing is based on a unique, giant dicynodont-theropod dinosaur fauna from Lipie Śląskie, Poland, thought to be Rhaetian in age, due to conjectural botanical and conchostracan (but not tetrapod) evidence. On the other hand, an age assignment for the Lipie fauna to the mid-Norian (Revueltian) has been demonstrated recently by regional integrative stratigraphic data. To test once more this still debated age assignment, we recall the rationale of Georges Cuvier in the study of the fossil record ('the best documents of Earth's past are fossilized large tetrapods'). This approach was applied successfully 200 years ago to the species extinction dilemma. In light of the worldwide distribution of dicynodonts, the alleged compositional paradox of the 'Rhaetian' fauna from Poland can be significantly reduced by its recognition as a more 'normal' early-middle Norian assemblage. The simple megafaunal correlation appears to be conclusive. Thus, there was a major pulse of dicynodont extinction at the end of the Carnian, with the final extinction of the few remaining species happening in the Norian. ARTICLE HISTORY
The major goal of the project "The evolution of terrestrial environments of the Upper Silesian Keuper as biotopes of vertebrates", granted for Grzegorz Racki by the Ministry of Science and Higher Education (2009–2013), was an exhaustive, integrated study of the bone-enriched middle Keuper interval in terms of stratigraphy, sedimentology, mineralogy and geochemistry. The new website "Bone-bearing Keuper of the Upper Silesia, southern Poland" (http://www.ing.pan.pl/Keuper/Bone-bearing_Keuper-1.htm) presents in English the results of this project. The significant achievements are only a starting point to a comprehensive presentation of the complex Keuper themes, jointly with an extensive repository of regional literature (above 420 full-texted publications since 1790). In addition, the main results of the grant, as well as diversity of their implications for future studies are summarized herein , with emphasis on controversial geochronological aspects in vertebrate paleontology (how many bone-rich levels?), and in a broad historical context.
Newly excavated Middle Triassic reptile Chirotherium, Rhynchosauroides and horseshoe crab Kouphichnium imprints from the uppermost Pelsonian megatracksite Bernburg, Germany (Central Europe) represent different behavioural trackways. The Chirotherium/Rhynchosauroides/Kouphichnium track assemblage of the lower intertidal carbonate flats is dominated by well-known horseshoe crab tracks of various subaquatic benthic movements which were all left on mud-cracked biolaminites in reproduction coastal zones. Most abundant reptile Rhynchosauroides trackways (50 % of reptile tracks) are oriented more beach-parallel (to Rhenish Massif Island) as a result of food searching along the intertidal seismic-influenced coast (16 slickensided biolaminate layers within 2 m biolaminates due to Alpine fold belt and Germanic intracratonic Basin tectonics), most probably for feeding on high abundant horseshoe crab eggs resulting from mating events in the lower intertidal. Large basal archosaur predators (?Ticinosuchus) produced large Chirotherium trackways (25 % of reptile tracks) which are represented in the new material with exceptional unusual trackways (slipping and side steps), but in directions to and from the beach to the Rhenish Massif main land, indicating predation on small reptiles. Finally, medium-sized Chirotherium trackways of subadult animals are present (25 % of reptile tracks). One trackway has a unique “feeding place” area, indicating the unexpected either predation, playing or feeding of a basal archosaur on a horseshoe crab. The horseshoe crab migrations from the North Tethys onto the extended mating intertidal mud flat beaches of the Germanic Basin, and recently known even into Chinese lagoons migrating limulid populations of different horseshoe crab species must have caused a global and seasonal food chain reaction, whereas Macrocnemus reptiles (Rhynchosauroides trackmaker) might have fed only on Millions of their eggs.
We redescribe the holotype of the saurischian dinosaur Staurikosaurus pricei Colbert, 1970 from Late Triassic Santa Maria Formation (southern Brazil), following additional preparation that revealed new anatomical features. A revised diagnosis is proposed and the published synapomorphies for Dinosauria and less inclusive clades (e.g. Saurischia) are evaluated for this species. Some characters previously identified as present in the holotype, including the intramandibular joint, hyposphene-hypantrum articulations in dorsal vertebrae, and a cranial trochanter and trochanteric shelf on the femur, cannot be confirmed due to poor preservation or are absent in the available material. In addition, postcranial characters support a close relationship between S. pricei and Herrerasaurus ischigualastensis Reig, 1963 (Late Triassic, Argentina), forming the clade Herrerasauridae. Several pelvic and vertebral characters support the placement of S. pricei as a saurischian dinosaur. Within Saurischia, characters observed in the holotype, including the anatomy of the dentition and caudal vertebrae, support theropod affinities. However, the absence of some characters observed in the clades Theropoda and Sauropodomorpha suggests that S. pricei is not a member of Eusaurischia. Most morphological characters discussed in previous phylogenetic studies cannot be assessed for S. pricei because of the incompleteness of the holotype and only known specimen. The phylogenetic position of S. pricei is constrained by that of its sister taxon H. ischigualastensis, which is known from much more complete material.
The evidence of the Dinosauromorpha, as defined phylogentically, by Rotodactylus tracks of the Olenekian predates by several million years the first osteological record of lagosuchians in the Ladinian....
Vertebrate footprints occur in the Middle Buntsandstein (Lower Triassic) Labyrinthodontidae Beds exposed at Wiory in the northeastern margin of the Holy Cross Mountains (Poland). They represent the richest footprint assemblage from the Middle Buntsandstein in Europe known to date. This assemblage comprises 11 ichnospecies representing seven ichnogenera attributable to amphibians and reptiles. The following new ichnotaxa are erected: Prorotodactylidae ichnofam. n., Prorvtodactyhis minis ichnogen. et ichnosp. n., Capitosauroides fuglewiczi ichnosp. n., Brachychirotherium wiorense ichnosp. n., hochirotherium gierlinskii ichnosp. n., Synaptichnium kotanskii ichnosp. n., and Rhynchosauroides rdzaneki ichnosp. n. The Prorotodactylus trackmakers possibly represent a systematic group close to that from which the Rotodactylus trackmakers and dinosaurs originated.
Approximately 40% of a skeleton including cranial and postcranial remains representing a new genus and species of basal neotheropod dinosaur is described. It was collected from fallen blocks from a sea cliff that exposes Late Triassic and Early Jurassic marine and quasi marine strata on the south Wales coast near the city of Cardiff. Matrix comparisons indicate that the specimen is from the lithological Jurassic part of the sequence, below the first occurrence of the index ammonite Psiloceras planorbis and above the last occurrence of the Rhaetian conodont Chirodella verecunda. Associated fauna of echinoderms and bivalves indicate that the specimen had drifted out to sea, presumably from the nearby Welsh Massif and associated islands (St David’s Archipelago). Its occurrence close to the base of the Blue Lias Formation (Lower Jurassic, Hettangian) makes it the oldest known Jurassic dinosaur and it represents the first dinosaur skeleton from the Jurassic of Wales. A cladistic analysis indicates basal neotheropodan affinities, but the specimen retains plesiomorphic characters which it shares with Tawa and Daemonosaurus.
Late Jurassic material of small theropod and ornithopod dinosaur footprints are reported from the northeastern slope of the Holy cross Mountains, Poland. the ichnites occur in five lithostratigraphical units of an epicontinental basin in central Poland. Small theropod tracks, Wildeichnus isp. and Jialingpus isp., came from the bałtów Platy Limestones, bałtów coral Limestones and wierzbica Oolite and Platy Limestones. Four specimens of small ornithopod footprints, assigned to Dinehichnus isp., were found in the błaziny Oolite Limestones and wierzbica Oolite and Platy Limestones. a medium-sized ornithopod footprint, identified as cf. Dinehichnus isp., was discovered in the Ożarów Oolite and Platy Limestones. the described footprints from the Upper Jurassic of Poland are smaller than similar types of ichnites from other parts of the world. the Polish Late Jurassic dinosaur community probably represented a diminutive insular fauna.
The material of the earliest poposaurid rauisuchian, Bromsgroveia walkeri, is described from the Bromsgrove Sandstone Formation (Middle Triassic) of the central Midlands of England. The structure of the ilium is less derived than it is in Lythrosuchus and much less so than in Poposaurus (both Upper Triassic, southwestern USA). Teratosaurus suevicus is a rauisuchid on the basis of a referred ilium from the Middle Stubensandstein (Upper Triassic) of Stuttgart, Germany.
A description of new ammonoid specimens (Acrochordiceras aff. damesi, cf. Acrochordiceras sp. indet., Discoptychites cf. dux, ?Paraceratites sp., cf. Balatonites sp. indet., Beneckeia buchi) form the Lower Muschelkalk (Anisian, Middle Triassic) of Silesia (southern Poland) is presented. The detailed stratigraphic position of the new finds is given. The description is supplemented with a list of all species of ammonoids found hitherto in Silesia, which was a southern part of the Germanic Basin during the Anisian. Beneckeia and Noetlingites were typical of epicontinental seas and usually appeared in the early part of transgressions. Other ammonoids entered from the Tethys into the epicontinental sea of the Germanic Basin during the maxima of transgressions. Some of them (balatonitids, paraceratitids, bulogitids, Discoptychites and probably Acrochordiceras) were successful colonizers which established their own populations in the Germanic Basin and evolved towards morphologies typical of epicontinental seas. Other (Beyrichites sp., Paraceratites binodosus, and 'Trachyceras' sp.) are regarded as unsuccessful immigrants or empty shells drifted post-mortem from the Tethys.
The holotype of Plateosaurus engelhardti MEYER, 1837 (very incomplete skeleton, Feuerletten [Trossingen Formation]. upper Middle Keuper, Upper Norian, Germany), the rare species, has two autapomorphies: sacral rib 1 originates from complete length of centrum 1 and rib 2 from the posterior 75% of centrum 2 (referred Ellingen individual has distally straight femur plus two other autapomorphies: ventrally wedge-shaped proximal caudal centra, pubis with open obturator foramen). Three German non-engelhardti species have two synapomorphies in the skull: a medial palatine "peg" and a sub-vertical lamina between the basipterygoid processes. Plateosaurus longiceps JAEKEL, 1913 (numerous specimens, Knollenmergel [Trossingen Formation], Halberstadt) is the valid species, with P. trossingensis FRAAS, 1913 (=P. integer, FRAAS, 1915 = P. fraasianus HUENE, 1932; numerous specimens, Upper Stubensandstein [upper Löwenstein Formation], Trossingen) as a junior synonym. P. erlenbergiensis HUENE, 1905 (incomplete skull and skeleton; Knollenmergel, Erlenberg) is generically indeterminate because the holotype lacks the sacrum, ilium and proximal pubis. Non-engelhardti prosauropod specimens from the upper Norian of most other localities in Germany, France, Switzerland and Greenland are probably referable to P. longiceps. Camelotia borealis GALTON, 1985 (Rhaetian, England) is a valid taxon of melanorosaurid prosauropod but the remaining species of Plateosaurus are nomina nuda or nomina dubia. The third sacral vertebra of P. engelhardti and P. longiceps is a caudosacral; it is a dorsosacral in Ruehleia bedheimensis GALTON, 2001 (several partial skeletons, Knollenmergel [Trossingen Formation], near Römhild, Thuringia).
Vertebrate remains, mostly nothosaurid vertebrae and long bonesarchosaur partially presetted long bones and teeth (probably rauisuchid remains)fish teeth and scalesare described from the Lower Keuper Miedaiy Beds (LadinianMiddle Triassic) of MiedaiySilesiaSW Poland. The analyzed vertebrate fossils were collected from three lithologie ally different types of deposits. The first assemblagewhich contains nothosaurid and fish remainsoccurs in yellowish dolomiteswhere poorly preseved invertebrate macrofossils were also found (marine bivalves and brachiopods). In grey-yellowishsometimes greenish or red claysrare isolated bones and teeth of large archosaur were found. In sandstone intercalations partially preserved and highly disarticulated fish fossils were identified. In all assemblages osteological remains are generally very well preserved. This new interesting vertebrate bones association from the upper part of the Middle Triassic marginal-marine strata of Poland has been correlated with age-equivalents from other regions of Europe.
Many of the best preserved teeth and bones of archosaurian reptiles found in 1834 in an Upper Triassic Rhaetian fissure fill on Durdham Down in Clifton (now in Bristol), southwest England were destroyed in 1940. Based on an 1875 map, the site is positively identified as within Quarry Steps Quarry. This paper includes an annotated catalogue, copies of most of the illustrations from 1840 to 1908, and photos of important extant specimens. Most of the recognizable, mostly unassociated and incomplete bones have long been referred to the basal sauropodomorph dinosaur Thecodontosaurus RILEY & STUTCHBURY, 1836 (as T. antiquus MORRIS, 1843), with gracile and robust morphs of several of the appendicular bones as a sexual dimorphism. The deltopectoral crest of unassociated Clifton humeri is plesiomorphic for basal sauropodomorphs, being anteroposteriorly high and markedly asymmetrical in lateral view with a short edge distal to the very prominent apex. The apex is at 40% (measured perpendicular to long axis of humerus) of total length in gracile ones and +50% in robust ones of the same size. However, the former position is plesiomorphic for sauropodomorphs, the latter derived, and no other basal sauropodomorph species has such a marked dimorphism. The only partial skeleton from Clifton, which includes a forelimb and girdle, has a third humeral morph with a low symmetrical deltopectoral crest with a rounded apex at 25% of length. Whatever the status of the gracile and robust morphs, the characters of referred postcranial bones from Clifton cannot be used to distinguish the species of Thecodontosaurus RILEY & STUTCHBURY, 1836 that, along with T. antiquus RILEY & STUTCHBURY vide OWEN, 1842, may be a nomen dubium. However, T. antiquus is retained for the slender humeral morph pending the description of referred material from a Rhaetian fissure fill at Tytherington Quarry, Avon. In the humerus of Pantydraco (Thecodontosaurus) caducus (Upper Triassic/Lower Jurassic, Wales) the apex of the asymmetrical deltopectoral crest is at 40% of the length and the process is low, a morph that is not represented at Clifton. The Clifton forelimb and girdle is made the holotype of Asylosaurus yalensis n. gen. et sp. The manus shows lateral reduction, so phalangeal formula is 2-3-4-2-71, and the humerus has a large medial tubercle (small in Welsh humerus). The other Clifton bones are identified as either : A. very basal Sauropodomorpha indet (could be Asylosaurus or Thecodontosaurus, includes slender morph bones) ; B. Anchisauria indet (more derived than A, includes robust morph bones) ; or G basal Sauropodomorpha indet (could be A or B). An ilium and two femora are very basal Theropoda (or possibly Dinosauriformes) ; other theropod remains include a small tooth crown with fine perpendicular denticles, a metacarpal I, a slender recurved manual ungual, and an astragalus. A dorsal centrum may be from an ornithischian dinosaur. Rileyasuchus KUHN, 1961 (type species Palaeosaurus platyodon RILEY & STUTCHBURY, 1840), a nomen dubium, is a heterodont crurotarsal phytosaur now represented by two teeth and two humeri. The denticles are angled slightly apically on the expanded mesial blade and perpendicular to the distal edge. Palaeosauriscus KUHN, 1959 (type species Palaeosaurus cylindrodon RILEY & STUTCHBURY, 1840) is based on lost teeth; it is Archosauria indet but may be a valid taxon based on the subcircular cross-section and fine, obliquely inclined denticles. A few bones are none of the above and are Archosauria indet (dentary with teeth, scapula-coracoid) and even Reptilia indet (?prootic, parietal, distal femur, tibia, metapodial).
Apart from characters of the dentary (proportional shortness, also Saturnalia tupiniquim) and vertebrae of proximal third of tail (posterior position of antero-posteriorly short neural spine on arch, absence of ventral furrowing on centra ; both also Efraasia minor), the bones of very basal sauropodomorphs from the Rhaetian (Upper Triassic) fissure fill in Clifton near Bristol (including holotypes of Thecodontosaurus antiquus, Asylosaurus yalensis ; taxon with robust humerus) share no diagnostic characters with those of Pantydraco caducus from the Rhaetian of South Wales. This taxon is diagnosed by four autapomorphies : median fusion of the nasals, prominent medial tubercle from posterior part of surangular, epipophyses of cervical vertebrae 3-5 form flat plates that overhang the posterior margins of the postzygapophyseal facets but do not form raised ridges on the dorsal surface of the postzygapophysis, and the fossae, possibly pneumatic, prominent on the neurocentral suture of cervical vertebrae 6-8 and shallow on the lateral part of centrum 9. The dentary is deep and short, with maximum height of more than 20 % of length (also Saturnalia tupiniquim, Thecodontosaurus antiquus), occupying less than 40% of total mandibular length (also Saturnalia tupiniquim). The ilium is tall with a long anterior process (also Anchisaurus polyzelus) and a short postacetabular process with the plesiomorphic absence of a brevis shelf. Other plesiomorphic characters include the lack of a buccal emargination on the dentary (also Saturnalia tupiniquim) ; teeth all recurved in lateral view; neck short with mid-cervical centra less than three times as long as wide (also Riojasaurus incertus, "Gyposaurus" sinensis); and humerus with a uniquely small tubercle medial to head and an antero-posteriorly low (also Asylosaurus yalensis) asymmetrical deltopectoral crest with the apex at 40 % of humeral length. At least three different sized individuals are preserved and the new skeletal reconstruction, with the posterior region scaled up to match the larger holotype, indicates a more bipedal animal than the more quadrupedal pose based on the incorrect premise that the two main blocks represent one individual. The specimens represent juveniles as indicated by the proportionally large skull with large orbits and short, high snout, slender postorbital bone, separation of most of bones of braincase, large metotic fissure and fenestra ovalis, low maxillary and dentary tooth counts, open neurocentral sutures of cervical vertebrae, and incomplete ossification of distal ends of the femur and metatarsals. The diversity of basal sauropodomorphs from the Rhaetian of Wales and England adjacent to the Severn Estuary is high with five taxa (Pantydraco caducus, three from Clifton, large basal sauropod Camelotia borealis from Somerset).
Mass accumulations of vertebrate fossils in the tetrapod "graveyard" at Krasiejów near Opole, SW Poland, occur in a vast lacustrine marly claystone horizon and claystone lenses of various extent within fluviatile cross-laminated mudstone. These fossil assemblages do not differ from each other in taxonomic composition, but the proportions of aquatic to land animals are dramatically different. We attempted to separate these two components of the assemblages to restore the original composition of the biota. The lacustrine biocoenosis component of Krasiejów includes characean algae, various molluscs and arthropods, ganoid and dipnoan fishes, the phytosaur Paleorhinus, and the temnospondyl amphibian Metoposaurus as the most common vertebrate. The capitosaurid labyrinthodont Cyclotosaurus probably occupied the lake shore. The inland vertebrate community was dominated by the herbivorous aetosaur Stagonolepis and the small herbivorous dinosaur Silesaurus, which probably were the prey for the rauisuchian Teratosaurus. The geological age of the Krasiejów strata can be determined, although with a rather low resolution, based on position of various members of its fauna in their evolutionary lineages. Biostratigraphic and sequence stratigraphy evidence may improve the precision of this dating. The strata seem to correspond with the upper part of the Weser Formation in Germany, believed to be of Late Carnian age.
The fossil record of abelisauroid carnivorous dinosaurs was previously restricted to Cretaceous sediments of Gondwana and probably Europe. The discovery of an incomplete specimen of a new basal abelisauroid, Berberosaurus liassicus, gen. et sp. nov., is reported from the late Early Jurassic of Moroccan High Atlas Mountains. Phylogenetic analysis recovers Ceratosauroidea and Coelophysoidea as sister lineages within Ceratosauria, and Berberosaurus as a basal abelisauroid. Berberosaurus is the oldest known abelisauroid and extends the first appearance datum of this lineage by about 50 million years. The taxon bridges temporal, morphological, and phylogenetic gaps that have hitherto separated Triassic to Early Jurassic coelophysoids from Late Jurassic through Cretaceous ceratosauroids. The discovery of an African abelisauroid in the Early Jurassic confirms at least a Gondwanan distribution of this group long before the Cretaceous.
A partial but largely articulated skeleton of a ‘rauisuchian’ archosaur from Late Upper Triassic strata of the Durham sub-basin, Deep River basin, Newark Supergroup, North Carolina, represents a new species of Postosuchus Chatterjee, 1985. It represents the first record of this taxon from eastern North America. The well preserved specimen includes cranial bones, a largely articulated right manus, right and left pedes, pubes, axis, several postaxial cervical, dorsal, and caudal vertebrae, chevron bones, osteoderms, interclavicle, clavicles, cervical ribs, a sacral rib, and a complete set of gastralia. The skeletal elements are described and compared to those of other ‘rauisuchians’. An apparant autapomorphy of Postosuchus alisonae includes a well developed flange on the proximal portion of metacarpal II fitting into strongly proximally grooved metacarpal I. The new specimen includes many bones previously unknown for Postosuchus and it allows a more complete differentiation of Postosuchus from other ‘rauisuchian’ genera. Diagnostic features of this genus include an axis with two ventral keels; postaxial cervical centra with strongly developed single ventral keels that are anteriorly and/or posteriorly extended into hypapophyses; short ribs on the anterior cervical vertebrae; heart-shaped cervical neural ‘spine tables’; a subrectangular, relatively short coracoid; and proportionately short manus with dorsoventrally compressed, reduced, blunt unguals on manual digits III and IV. Morphological comparisons indicate a close relationship between Postosuchus and Batrachotomus and possibly also Tikisuchus.
Effigia okeeffaee is named based on a well-preserved nearly complete skeleton from the Upper Triassic (?Rhaetian) "siltstone member" at Ghost Ranch, northern New Mexico. The skull is described and compared to other suchian and basal archosaurs. The maxilla and premaxilla are edentulous, and a rhamphotheca was possibly present in life. Effigia conclusively indicates that the skull of Shuvosaurus and the postcrania of "Chatterjeea" belong to the same taxon. Furthermore, the close relationship between Shuvosaurus and Effigia indicates that both taxa are nested within the suchian clade and not within Ornithomimisauria. However, the similarity in features in the skull and postcrania of Effigia and ornithomimids suggests extreme convergence occurred between the two clades. A clade containing Arizonasaurus, Bromsgroveia, Poposaurus, Sillosuchus, Shuvosaurus, and Effigia is suggested based solely on shared derived character states. Additionally, a clade (Clade Y) containing Sillosuchus, Shuvosaurus, and Effigia is well supported by further derived character states. The distribution and temporal pattern of members of Group Y suggest that members of Group Y are present in the early Middle Triassic through the Latest Triassic of North America, and one member of the clade, Sillosuchus, was present in South America.
A new ceratite locality from Goluchowice (Upper Silesia, Poland) is described. Ceratites from the spinosus group found there include Ceratites (Acanthoceratites) cf. praespinosus, found for the first time in Upper Silesia. Five ceratite zones are proposed for that region: pulcher, robustus, compressus, evolutus and spinosus. The taxonomic compositions of individual ceratite zones from Upper Silesia are almost identical to those of corresponding zones from the Holy Cross Mountains. However, ceratite zones in Poland show lower taxonomic diversity than their equivalents in Germany.
Three species are currently recognized within the genus Cymatosaurus from the late Scythian and early Anisian of Europe, vis. Cymatosaurus fridericianus v. Fritsch, 1894, Cymatosaurus latifrons Gurich, 1884, and Cymatosaurus multidentatus (F.v. Huene, 1958). All other previously described species of Cymatosaurus are considered either junior synonyms of Cymatosaurus latifrons or a nomen dubium. Germanosaurus schafferi Arthaber, 1924, is recognized as a separate genus and species within the Nothosauridae, sister-group of the Nothosaurinae. Germanosaurus (Eurysaurus) latissimus (Gurich, 1891) is treated as a nomen dubium. A cladistic analysis based on the critical revision of the genera Cymatosaurus and Germanosaurus improves resolution among Triassic stem-group Eosauropterygia. The resulting cladogram is used as the basis for a comparison of phylogenetic pattern and stratigraphic distribution of the Sauropterygia.
A new genus and species of protorosaur is described on the basis of material originally referred to Tanystropheus antiquus from the Upper Buntsandstein of the Black Forest, Germany. The new taxon is characterized by eight cervical vertebrae that bear markedly elongate cervical ribs, a shagreen of denticles covering the vomers, palatines and pterygoids, a bifurcate second sacral rib, a well-ossified tarsus with three distal tarsals, and an elongate proximal phalanx on digit five. The status of Tanystropheus antiquus is discussed and, while it is retained, its validity is questioned.
Tikisuchus romeri n. gen. and sp. is a rauisuchid thecodontian from the Late Triassic Tiki Formation of India and is the first rauisuchid material to be recorded from Asia. The skull is very large in relation to the presacral length and is equipped with sharp, serrated teeth. The astragalus has a very high dorsal process and the calcaneal tuber is short; the ankle joint is of “crocodile-normal” type.
The rauisuchids were the dominant terrestrial predators during the Triassic and shared similar ecological niches with the emerging theropods. The agility and superior locomotion of theropods may have contributed to their success and to their eventual replacement of the rauisuchids at the end of the Triassic.
Based on new material from the top of the Late Jurassic Shangshaximiao Formation of Xiaogu, Qianwei County, southwestern Sichuan Basin, a new sinraptorid carnosaur Leshansaurus qianweiensis gen. et sp. nov. is erected. It is distinguished from other carnosaurs by supraoccipital with a sharp midline ridge; relatively longer frontal with a ratio of the maximum length to the maximum width about 2. 4; basipterygoid processes of basisphenoid slender; atlantal intercentrum horseshoe-shaped; diapophyses of dorsal vertebrae relatively slender; neural spines of dorsal and sacral vertebrae very thin; ventral keel of sacral vertebrae distinctly defined; ilium with a conspicuous ridge medially along acetabular edge. This new dinosaur was the latest carnosaur presently known in Sichuan Basin. Its discovery extends the horizontal and geographical distributions of the carnosaurs in Sichuan Basin, and is significant in the evolution of the carnosaurs.
This chapter discusses the anatomy, evolution, biogeography, taphonomy, paleoecology, and paleobiology of prosauropaud dinosaurs. Prosauropods have been found on all the major continents, including Antarctica. They were medium- to large-sized, bipedal, facultatively bipedal or quadrupedal sauropodomorphs with long necks and tails. Prosauropods were probably the slowest of the bipedal dinosaurs but better runners than most other quadrupedal dinosaurs. Among prosauropods, Saturnalia and Thecodontosaurus are considered fully bipedal. Riojasaurus and other melanorosaurids were fully quadrupedal and the remaining prosauropods were probably only facultatively bipedal.
A sedimentological and palaeontological analysis of Los Colorados Formation sequence was undertaken in order to interpret the depositional environment and palaeoclimatic conditions. The sequence, characterised by sandstone and mudstone, was deposited by moderately sinuous fluvial systems, and interfingers laterally with and grades into horizontally bedded flood-plain deposits. Towards the top of the sequence, thin-bedded fossil-bearing sandstones and mudstones were deposited in ponds and as crevasse splays in overbank settings. The high abundance of large herbivorous tetrapods (prosauropods), medium- to large-sized browsers with derived masticatory apparatus (dicynodonts), and medium-sized, probably herbivorous, amphibious forms (aetosaurs), together with the sedimentological features of the unit, suggest that the climatic conditions in the area during the Late Triassic were wetter than previously suggested. The lack of a vegetation record in Los Colorados Formation is interpreted as a taphonomic problem related to the oxidizing conditions during deposition.
