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

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

3D model and accompanying dataset related to the publication: A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny

The present contribution contains the 3D model and dataset analyzed in the following publication: Scheyer, T. M., J. M. Neenan, T. Bodogan, H. Furrer, C. Obrist, and M. Plamondon. 2017. A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny. Scientific Reports, https://doi.org/10.1038/s41598-017-04514-x

The braincase, brain and palaeobiology of the basal sauropodomorph dinosaur <i>Thecodontosaurus antiquus</i>

Ballell, Antonio, King, J Logan, Neenan, James M, Rayfield, Emily J, Benton, Michael J (2021): The braincase, brain and palaeobiology of the basal sauropodomorph dinosaur Thecodontosaurus antiquus. Zoological Journal of the Linnean Society 193 (2): 541-562, DOI: 10.1093/zoolinnean/zlaa157, URL: https://academic.oup.com/zoolinnean/article/193/2/541/603272

Aquatic Habits and Niche Partitioning in the Extraordinarily Long-Necked Triassic Reptile Tanystropheus

Tanystropheus longobardicus is one of the most remarkable and iconic Triassic reptiles. Mainly known from the Middle Triassic conservation Lagerstätte of Monte San Giorgio on the Swiss-Italian border, it is characterized by an extraordinarily long and stiffened neck that is almost three times the length of the trunk, despite being composed of only 13 hyper-elongate cervical vertebrae [1-8]. Its paleobiology remains contentious, with both aquatic and terrestrial lifestyles having been proposed [1, 9-12]. Among the Tanystropheus specimens, a small morphotype bearing tricuspid teeth and a large morphotype bearing single-cusped teeth can be recognized, historically considered as juveniles and adults of the same species [4]. Using high-resolution synchrotron radiation microtomography (SRμCT), we three-dimensionally reconstruct a virtually complete but disarticulated skull of the large morphotype, including its endocast and inner ear, to reveal its morphology for the first time. The skull is specialized toward hunting in an aquatic environment, indicated by the placement of the nares on the top of the snout and a "fish-trap"-type dentition. The SRμCT data and limb bone paleohistology reveal that the large morphotype represents a separate species (Tanystropheus hydroides sp. nov.). Skeletochronology of the small morphotype specimens indicates that they are skeletally mature despite their small size, thus representing adult individuals of Tanystropheus longobardicus. The co-occurrence of these two species of disparate size ranges and dentitions provides strong evidence for niche partitioning, highlighting the surprising versatility of the Tanystropheus bauplan and the complexity of Middle Triassic nearshore ecosystems.© 2020 Elsevier Inc. The attached document is the author(’s’) final accepted/submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

Major evolutionary transitions, in which animals develop new body plans and adapt to dramatically new habitats and lifestyles, have punctuated the history of life. The origin of cetaceans from land-living mammals is among the most famous of these events. Much earlier, during the Mesozoic Era, many reptile groups also moved from land to water, but these transitions are more poorly understood. We use computed tomography to study changes in the inner ear vestibular system, involved in sensing balance and equilibrium, as one of these groups, extinct crocodile relatives called thalattosuchians, transitioned from terrestrial ancestors into pelagic (open ocean) swimmers. We find that the morphology of the vestibular system corresponds to habitat, with pelagic thalattosuchians exhibiting a more compact labyrinth with wider semicircular canal diameters and an enlarged vestibule, reminiscent of modified and miniaturized labyrinths of other marine reptiles and cetaceans. Pelagic thalattosuchians with modified inner ears were the culmination of an evolutionary trend with a long semiaquatic phase, and their pelagic vestibular systems appeared after the first changes to the postcranial skeleton that enhanced their ability to swim. This is strikingly different from cetaceans, which miniaturized their labyrinths soon after entering the water, without a prolonged semiaquatic stage. Thus, thalattosuchians and cetaceans became secondarily aquatic in different ways and at different paces, showing that there are different routes for the same type of transition.Facultad de Ciencias Naturales y Muse

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

© 2020 National Academy of Sciences. All rights reserved. Major evolutionary transitions, in which animals develop new body plans and adapt to dramatically new habitats and lifestyles, have punctuated the history of life. The origin of cetaceans from land-living mammals is among the most famous of these events. Much earlier, during the Mesozoic Era, many reptile groups also moved from land to water, but these transitions are more poorly understood. We use computed tomography to study changes in the inner ear vestibular system, involved in sensing balance and equilibrium, as one of these groups, extinct crocodile relatives called thalattosuchians, transitioned from terrestrial ancestors into pelagic (open ocean) swimmers. We find that the morphology of the vestibular system corresponds to habitat, with pelagic thalattosuchians exhibiting a more compact labyrinth with wider semicircular canal diameters and an enlarged vestibule, reminiscent of modified and miniaturized labyrinths of other marine reptiles and cetaceans. Pelagic thalattosuchians with modified inner ears were the culmination of an evolutionary trend with a long semiaquatic phase, and their pelagic vestibular systems appeared after the first changes to the postcranial skeleton that enhanced their ability to swim. This is strikingly different from cetaceans, which miniaturized their labyrinths soon after entering the water, without a prolonged semiaquatic stage. Thus, thalattosuchians and cetaceans became secondarily aquatic in different ways and at different paces, showing that there are different routes for the same type of transition

Evolutionary Origins, Palaeoecology and Systematics of Placodont Marine Reptiles from the Triassic of Europe and China

ACKNOWLEDGEMENTS I am extremely grateful to my supervisor, Dr. Torsten Scheyer, whose constant support and patience over the years have helped me beyond words. I have learnt a great deal from him: scientific methods, diplomacy, self-confidence and the ability to appreciate fine music and beers. I am incredibly grateful to him for choosing me for this project and consider him a friend as well as a mentor. I am also extremely grateful to Prof. Dr. Marcelo Sánchez for his constant good advice, useful discussions and constructive criticism. I feel truly privileged to have been a member of his working group, and have become a better scientist because of it. Prof. Dr. Hugo Bucher is also thanked for being a supportive, helpful director with a good sense of humour. I would also like to thank all the colleagues from outside the PIMUZ with whom I have had the honour of collaborating: Olivier Rieppel (Field Museum, Chicago), Li Chun (IVPP, Beijing), Da-Yong Jiang (GMPKU, Beijing), Nicole Klein (SIPG, Bonn), Hans Hagdorn (MHI, Ingelfingen), Andrea Tintori (Milan, Italy), Silvio Renesto (Varese, Italy), Franco Saller (Bozen, Italy), Federico Bernardini, Claudio Tuniz (both ICTP; Trieste), and Giuseppe Muscio (MFSN, Udine). Access to specimens was vital for the success of this project, so my deepest thanks go to Heinz Furrer (PIMUZ, Zurich), Joachim Rabold and Stefan Eggmaier (UMO, Bayreuth), Markus Moser and Oli Rauhut (BSPG, Munich), Rainer Schoch (SMNS, Stuttgart), Li Chun (IVPP, Beijing), and Da-Yong Jiang (GMPKU, Beijing), for allowing me to examine specimens and take many of them to be CT scanned. I am also very grateful to Walter Leis (Hochschule Aalen), Hou Yemao (IVPP, Beijing), Nicole Klein (SIPG, Bonn) and Federico Bernardini (ICTP, Trieste), who all assisted in the CT scanning of ACKNOWLEDGEMENTS 6 specimens. Indeed, processing and segmenting the vast amounts of CT data would have been impossible without the help of Lisa Rager (SMNS, Stuttgart) and Constanze Bickelmann (MHUB, Berlin). My deepest thanks also go to those who were always willing to discuss my project and help me with various issues: Robin O’Keefe (Marshall), Nick Fraser, Steve Brusatte (both in Edinburgh), Mike Benton, Tom Stubbs, Aude Caromel (all Bristol), Darren Naish (Southampton), Neil Kelley and Ryosuke Motani (both UC Davis). My sincerest thanks also go to my officemates and very good friends, Christian Kolb and Juan Carillo who have both supported me through the tougher periods of my PhD and have always been available for discussion and advice. I would also like to thank all my other friends at the PIMUZ, who have all made my time here both enjoyable and rewarding: Åsa Frisk, Fiona Straehl, Pat Putzi-Meier, Carlo Romano, David Ware, Morgane Brosse, Marc Leu, Lorena Tessitore, Borhan Bagherpour, Conni Bickelmann, Jorge Carillo, Linda Frey, Maddy Geiger, Markus Hebeisen, Dick Hofmann, Jasi Hugi, Romain Jattiot, Christian Klug, Dai Koyabu, Erin Maxwell, Carole ‘Bronzie’ Naglik, Lisa Rager, Anna Sanson, Beat Scheffold, Madlen Stange, Mirjam Fehlmann, Viv Jaquier, Alex Wegmann, Ingmar Werneburg and Laura Wilson. This thesis would not have been possible without the heroic efforts of Heike Götzmann, who has the ability to solve any problem without breaking a sweat, and Heini Walter, who can fix any IT-related issue. Nor could have I survived my time here without the love and support of Artemis Treindl and Christa Finkenwirth, who have both been incredible friends to me. Finally and most importantly, I would like to thank my family, Jane, Mike and Jordan for being incredibly supportive, patient and loving over my many years of education

The importance of Winterswijk for understanding placodontiform evolution

Placodontiformes are basal, semi-aquatic sauropterygians that mostly preyed upon hard-shelled organisms and often had substantial dermal armour. While their fossil remains are rare, they can be found in Triassic sediments throughout Europe, the Middle East and southern China, often in the form of their unusually large, tablet-shaped teeth. Winterswijk, however, boasts one of the most important fossil records for placodontiforms in the world, with two unique genera that are not currently known from anywhere else: Palatodonta bleekeri and Pararcus diepenbroeki. Other than these, more widespread genera are probably also represented in the form of Placodus sp. and Cyamodus sp

With plates and spikes - the heavily armoured Eusaurosphargis aff. dalsassoi

Besides the wealth of nothosaur and pachypleurosaur fossils from the Vossenveld Formation, there are fi ndings of bones that show very peculiar shapes, not easily attributable to the aforementioned groups. Among these are vertebrae with very long transverse processes, curved dorsal ribs with broadened portions known as uncinate processes, and peculiar shaped dermal armour (generally referred to as osteoderms), usually in the form of small bony cones. For a long time, the identity of these bones remained obscure, but lately, there is increasing evidence that all those materials belong to a single enigmatic diapsid, Eusaurosphargis, known from several European fossil localities

The cranial anatomy of Chinese placodonts and the phylogeny of Placodontia (Diapsida: Sauropterygia)

Placodonts are Triassic marine reptiles that inhabited the eastern and western margins of the Tethys Ocean (modern South China and Europe/Middle East). Although the crania of European taxa are relatively well understood, those of Chinese taxa have not been extensively studied, and most of them have not been incorporated into a compre- hensive phylogeny. Here we present the first reconstructions of all known Chinese placodont holotype skulls using micro-computed tomographic (μCT) scanning and/or detailed anatomical study. We also present the first phylogenetic analyses that incorporate all placodont genera using a general diapsid matrix that includes postcranial charac- ters, and a placodont-only cranial matrix. Results vary between the matrices; however, both support a monophyletic Placodontia with eastern taxa interspaced throughout, indicating no major separation between the eastern and western Tethyan realms. Support is strong for a western Tethyan origin of Placodontia, although the highly nested Placochelyidae first appear in the upper Middle Triassic of the eastern Tethys. Thus, all placodont clades appear to have originated in a period of intense speciation during the Middle Triassic