Swiss Journal of Palaeontology最新文献

{"title":"The first record of a shortnose chimaera-like egg capsule from the Mesozoic (Late Jurassic, Switzerland).","authors":"Yang Zhao, Jordan Bestwick, Jan Fischer, Dylan Bastiaans, Merle Greif, Christian Klug","doi":"10.1186/s13358-025-00352-x","DOIUrl":"10.1186/s13358-025-00352-x","url":null,"abstract":"<p><p>Chondrichthyan egg capsules, fossil and recent, have a taxonomical significance that can provide important insights into the occurrence and reproductive strategy of their producers. However, the rare occurrence of fossil capsules and their sometimes difficult identification hinder our understanding of their systematics and significance. <i>Laffonia</i> from the Late Jurassic of Switzerland and its probable junior synonym, <i>Pseudocaudina,</i> from the Late Jurassic lithographic limestones of southern Germany, have been interpreted in a variety of ways including as a fructification of a plant, a possible egg capsule of a shark or ray, a presumed holothurian, a possible actinarian, or even a ctenophore<i>.</i> Here, we redescribe the holotype of <i>Laffonia</i>, which has a fusiform body that is ornamented with over seven longitudinal ribs and two narrow striated flanges at its lateral edges. These morphological features are incompatible with a diploblast or echinoderm affinity, but highly resemble the characteristics of certain holocephalan egg capsules in several respects. Our phylogenetic analysis places <i>Laffonia</i> within a group containing the Carboniferous fossil capsules <i>Crookallia</i> and <i>Vetacapsula</i>, as well as recent chimaerid capsules. Thus, we suggest that the Mesozoic <i>Laffonia</i> represents an intermediate morphotype between the Carboniferous species and extant chimaerid capsules. <i>Laffonia</i> is the only known fossil chimaerid-like capsule from the Mesozoic so far, which offers novel insights into the morphology and evolution of holocephalan egg capsules.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00352-x.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"8"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11830639/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143450779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Massospondylus</i> embryos and hatchling provide new insights into early sauropodomorph ontogeny.","authors":"Ethan D Mooney, Tea Maho, Dylan C T Rowe, Diane Scott, Robert R Reisz","doi":"10.1186/s13358-025-00382-5","DOIUrl":"10.1186/s13358-025-00382-5","url":null,"abstract":"<p><p>Ontogeny and patterns of growth provide crucial insights into the evolution of dinosaurs and their biology, however, ontogenetic changes of the postcranial skeleton are generally poorly known and restricted to few species. Here, we report on the discovery of embryonic, eggshell, and hatchling material of the Early Jurassic sauropodomorph <i>Massospondylus</i> and provide new insights into the early life stages of early-diverging sauropodomorphs. The embryos described here represent a more advanced developmental stage than previously known embryonic materials and together show eggshells with progressive degrees of resorption correlating to embryonic development. The prominent \"thumb\" typical of early-diverging sauropodomorph dinosaurs also appears to be precociously ossified and ontogenetically variable. Together, these new <i>Massospondylus</i> embryos and hatchling indicate a quadrupedal posture and the resulting growth trajectory points to an important ontogenetically influenced ecological shift predicated on a continuum of locomotory dependent postural change, from obligate quadrupeds to obligate bipeds<i>.</i> Other Late Triassic and Early Jurassic sauropodomorph dinosaurs known from few ontogenetic stages also fit well on the extensive growth trajectory of <i>Massospondylus</i> with only modest variations in skull, neck, and limb proportions. This generally conservative body plan of early-diverging sauropodomorphs likely suggests a similar postural change for the early members of this large clade that preceded the obligate quadruped sauropods.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00382-5.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"44"},"PeriodicalIF":2.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12321941/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144796247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Craniomandibular osteology of a new massopodan sauropodomorph (Dinosauria: Sauropodomorpha) from the Late Triassic (latest Norian) of Canton Aargau, Switzerland.","authors":"Alessandro Lania, Ben Pabst, Torsten M Scheyer","doi":"10.1186/s13358-025-00373-6","DOIUrl":"10.1186/s13358-025-00373-6","url":null,"abstract":"<p><p>Non-sauropodan sauropodomorphs represented the most abundant and diverse herbivore component of the Gondwanan continental paleoecosystems during the Late Triassic. Nonetheless, a constantly increasing diversity has been recovered also from Laurasian formations, such as the Klettgau Formation, which is best exposed at the Gruhalde clay pit (Tonwerke Keller AG) in Frick, Canton Aargau, Switzerland. Despite being renowned for mass-accumulation horizons of the plateosaurid <i>Plateosaurus trossingensis</i>, a new fossiliferous layer was recently discovered above the \"<i>Plateosaurus</i> bonebeds\", yielding the holotype of the neotheropod <i>Notatesseraeraptor frickensis</i> as well as several partial articulated skeletons of an unknown sauropodomorph. The complete craniomandibular anatomy of an articulated skull, SMF 13.5.37, belonging to a partial skeleton, SMF 13.5, referred to this new latest Norian sauropodomorph from the Klettgau Formation is here presented. Micro-computed tomography scans (µCT) as well as segmentation techniques were employed in order to examine inaccessible craniodental features of the snout of the specimen under study. The osteological investigation and the anatomical comparison with related taxa unveiled a unique mosaic-like combination of plesiomorphic and apomorphic craniomandibular features, implying that the cranial anatomy of SMF 13.5.37 is transitional between non-massopodan plateosaurian and massopodan sauropodomorph morphologies, similarly to the Argentinian <i>Coloradisaurus brevis</i> from the mid-to-late Norian of the Los Colorados Formation. An intermixed craniomandibular condition is also reflected in the phylogenetic results, which resolve SMF 13.5.37 as a basal massopodan, branching out either at the first or third node of Massopoda, representing the first Laurasian non-sauropodiform massopodan. Even though the evolutionary trend towards a complete massopodan-like architecture needs to be further tested with the study of the postcranium, SMF 13.5.37 unequivocally represents the skull of a new massopodan sauropodomorph taxon from Switzerland, shedding light on a more diversified herbivorous dinosaurian paleofauna from the Norian comparable to those of South America and Africa, as it represents the fourth officially recognized non-sauropodan sauropodomorph along with <i>Plateosaurus trossingensis</i>, <i>Gresslyosaurus ingens</i> and <i>Schleitheimia schutzi</i>.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00373-6.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"39"},"PeriodicalIF":2.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12321939/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144790802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Delayed skeletal maturity in dwarf, medium and giant Pleistocene insular deer (<i>Candiacervus</i>) indicating a slower life history regardless size shift.","authors":"Felix Snoodijk, Teresa Calderón, George A Lyras, Alexandra A E van der Geer","doi":"10.1186/s13358-025-00413-1","DOIUrl":"10.1186/s13358-025-00413-1","url":null,"abstract":"<p><p>Insular conditions, such as reduced levels of resources, predation and competition, may affect life history traits of island mammal species, promoting a shift towards a slow life history. This pattern has been found in several species of insular dwarf deer but has not been tested for island deer that were subject to gigantism, which may evolve opposite life history shifts. The Pleistocene deer genus of Crete (Greece), <i>Candiacervus,</i> provides an ideal case to test this potential difference, because this endemic genus comprised dwarf as well as giant forms in an otherwise depauperate mammalian fauna. Here, we tested maturation patterns in this genus using a palaeohistological approach. We found that small, medium and larger forms of <i>Candiacervus</i> all demonstrated delayed skeletal maturity compared to their putative ancestor fallow deer (<i>Dama dama</i>) as well as similar-sized mainland deer. This is the first report showing that insular deer that are either subject to gigantism or retained ancestral size, also displayed adaptations to a slow life history similar to insular deer that underwent dwarfism. This research contributes to our understanding of how insular conditions may influence life history patterns in a species radiation of deer.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"78"},"PeriodicalIF":2.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12727720/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145835353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The first occurrence of <i>\"Plesiochelyidae</i>\" marine turtles in the early cretaceous of South America.","authors":"Edwin-Alberto Cadena, Jorge D Carrillo-Briceño, Dylan Bastiaans, Tandra Fairbanks-Freund, Loïc Costeur, Torsten M Scheyer","doi":"10.1186/s13358-025-00394-1","DOIUrl":"https://doi.org/10.1186/s13358-025-00394-1","url":null,"abstract":"<p><p>Thalassochelydians represent one of the earliest radiations of coastal to marine-adapted turtles, spanning from the Jurassic to Cretaceous periods. This study describes <i>Craspedochelys renzi</i> sp. nov., a new thalassochelydian, \"plesiochelyid\" turtle from the Hauterivian stage of the Early Cretaceous in Colombia. It is the youngest and the only known record of \"<i>Plesiochelyidae</i>' outside Europe. The holotype, housed at the Naturhistorisches Museum Basel, was rediscovered after over 60 years and includes a partial shell, hindlimb bones, and caudal vertebrae. <i>C. renzi</i> shares key traits with \"<i>Plesiochelyidae</i>\", including a V-shaped posterior plastral lobe lacking an anal notch; an indentation at the hypoplastra-xiphiplastra contact; an \"intermediate\" bone between neural 8 and suprapygal 1; a fully ossified carapace and bridge; and absence of carapacial fontanelles. Within \"<i>Plesiochelyidae</i>\", it is assigned to <i>Craspedochelys</i> by its broader carapace, with an estimated length/width ratio of 4.12 for left costal 4, similar to other species in the genus; a relatively shorter plastron; and wider hyoplastra. Geological evidence links the specimen to the Moina Formation, a shallow marine deposit from the Hauterivian. This discovery expands the genus' spatial and temporal range, underscoring its evolutionary and paleobiogeographic significance. It highlights the importance of museum collections in re-evaluating long-overlooked specimens, enriching our understanding of past biodiversity and turtle dispersal patterns.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00394-1.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"52"},"PeriodicalIF":2.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12375516/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144980035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A redescription of <i>Glyptochelone suyckerbuykii</i> (Ubaghs, 1879), an enigmatic fossil sea turtle (<i>Chelonioidea</i>) from the Maastrichtian of the Netherlands and Belgium, sheds new light on fossil sea turtle shell variation and neural bone homology.","authors":"Juliette C L Menon, Walter G Joyce","doi":"10.1186/s13358-025-00389-y","DOIUrl":"10.1186/s13358-025-00389-y","url":null,"abstract":"<p><p>We here provide a redescription the Late Cretaceous (Campanian-Maastrichtian) fossil marine turtle <i>Glyptochelone suyckerbuykii</i> to document its anatomy and intraspecific variation. This redescription highlights the complete absence of a nuchal pedestal, presence of a radiating shell surface texture pattern easily differentiated from that of coeval marine turtles, and the presence of interneural elements, a characteristic unique among Late Cretaceous turtles. A phylogenetic analysis suggests that <i>Glyptochelone suyckerbuykii</i> is located at the base of <i>Dermochelyidae</i>, a dubious result likely resulting from missing data. To allow constructing phylogenetic characters based on the presence of supernumerary neural elements, we suggest a revised classification for the midline column of the carapace of turtles based on novel homology criteria as consisting of neurals, which are outgrowths of the neural arches, as opposed to preneurals, interneurals, and postneurals, which are independent bones that form in front, within, and posterior to the neural column, respectively. We suggest use of this novel classification in future phylogenetic analysis.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00389-y.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"62"},"PeriodicalIF":2.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12488835/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145234196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An almost complete cranium of <i>Asoriculus gibberodon</i> (Petényi, 1864) (Mammalia, Soricidae) from the early Pliocene of the Jradzor site, Armenia.","authors":"Hugo Bert, Loic Costeur, Sergei Lazarev, Georg Schulz, Davit Vasilyan, Olivier Maridet","doi":"10.1186/s13358-025-00357-6","DOIUrl":"https://doi.org/10.1186/s13358-025-00357-6","url":null,"abstract":"<p><p>We describe an almost complete fossil cranium of a shrew, identified as <i>Asoriculus gibberodon</i> (Petényi, 1864) from the early Pliocene of Jradzor site, Armenia. The sedimentary unit, which yielded the specimen, is an 11-m-thick package composed of white thinly-parallel-laminated diatomite laying at the base of the Jradzor section. It was dated at 4.29 ± 0.09 Ma based on the magnetostratigraphy and ⁴⁰Ar/³⁹Ar radioisotopic dating of a tephra layer located at the top of the diatomite package. The skull from Jradzor shows several synapomorphies that allow its assignment to the Soricinae subfamily and Neomyini tribe. Among Neomyini, as far as the cranium anatomy is known, the specimen from Jradzor is most similar to that of <i>Soriculus</i> and <i>Episoriculus</i>. Both petrosal bones are preserved and are studied thanks to a 3D modelling of their morphology based on a CT-scan. Compared with other eulipotyphlans, the bony labyrinth of <i>A. gibberodon</i> from Jradzor shows a morphology typical of soricids. Its anatomy also indicates a high-frequency auditory capability similar to that of modern shrews but cannot confirm an echolocation system neither does it shows any feature that can be related to a specific locomotory adaption or ecological characteristic. The discovery of this cranium inside diatomites, corresponding to a distal lacustrine environment, raises the question of the possible semi-aquatic adaptation of this species (this adaptation being known for other extant species of the family). However, <i>Soriculus</i> and <i>Episoriculus</i>, the two genera closest to <i>Asoriculus</i> based on cranial anatomy are not semi-aquatic and are clearly distinguished from semi-aquatic <i>Neomys</i> shrews. The inner ear morphology is more similar to that of terrestrial shrews despite the general similarities among soricids and suggests an echolocation-based orientation using high frequencies to navigate through low vegetation, which is often essential in high metabolic rate organisms to reduce energy expenditure. We therefore propose a terrestrial locomotion for <i>A. gibberodon</i>, consistent with its previously proposed paleoecological model, depicting it was a terrestrial species inhabiting wet or humid environments in close proximity to permanent bodies of water.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00357-6.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"19"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11996986/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144059245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New insights on the shell-crusher shark <i>Ptychodus decurrens</i> Agassiz, 1838 (Elasmobranchii, Ptychodontidae) based on the first known articulated dentition from the Upper Cretaceous of Croatia.","authors":"Manuel Amadori, Sanja Japundžić, Jacopo Amalfitano, Luca Giusberti, Eliana Fornaciari, Patrick L Jambura, Jürgen Kriwet","doi":"10.1186/s13358-024-00340-7","DOIUrl":"10.1186/s13358-024-00340-7","url":null,"abstract":"<p><p>A new lower tooth plate of <i>Ptychodus decurrens</i> from the Turonian (Upper Cretaceous) of the Dalmatian region (southern Croatia) is documented here for the first time. The specimen represents the first articulated dentition of a ptychodontid shark that has been discovered from the Balkan Peninsula and the most complete ever found for the un-cuspidate species <i>P. decurrens</i> up to now. The reconstruction of the entire lower dentition of <i>P. decurrens</i> based on this exceptionally well-preserved dentition shows a wider crushing plate than previously hypothesised with bulgy teeth limited to the central area. Even though a defined cusp is missing, the occlusal surface of the teeth is undeniably raised and bulgy in some un-cuspidate species of <i>Ptychodus</i> (e.g., <i>P. decurrens</i>). This compels us to reconsider the use of terms such as high- and low-crowned as well as cuspidate and un-cuspidate. In addition, specimens previously assigned to dubious species (<i>P. depressus</i>, <i>P. levis</i> and <i>P. oweni</i>) or even varieties (<i>P. polygyrus</i> var. <i>sulcatus</i> and <i>P. decurrens</i> var. <i>multiplicatus</i>) are reassigned here to <i>P. decurrens</i> based on a careful comparison of the type materials. The reassessment of tooth root morphologies provides indicative traits for the identification of different genera of ptychodontid sharks (<i>Paraptychodus</i> and <i>Ptychodus</i>). The taxonomic revision presented here is crucial for securing a stable taxonomy and systematics of the shell-crushing shark <i>P. decurrens</i>, as well as of all ptychodontid sharks. The resulting updated taxonomy, together with the description and reconstruction of the new crushing plate, greatly contribute to a better understanding of one of the most enigmatic families (Ptychodontidae) of Mesozoic elasmobranchs. The detailed investigation of the new dentition of <i>Ptychodus</i> from Dalmatia is also a further step towards the discovery of Upper Cretaceous ichthyofaunas of one of the most palaeontologically important areas of the Balkan Peninsula.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-024-00340-7.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"2"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11711565/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142973448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new seal from the Late Miocene of the Eastern Paratethys highlights the past regional diversity of true seals (Phocidae).","authors":"Pavlo Otriazhyi, Theodor Obadă, Oleksandr Kovalchuk, Davit Vasilyan, Pavel Gol'din","doi":"10.1186/s13358-025-00372-7","DOIUrl":"10.1186/s13358-025-00372-7","url":null,"abstract":"<p><p>True seals rapidly evolved in many forms in the epicontinental basin of Paratethys during the Miocene. However, most of their nominal taxa so far were proposed based on isolated limb bones, and their taxonomy has long been under discussion<i>.</i> Here we describe a new articulated skeleton MCFFM V-150 of a medium-sized seal with pachyosteosclerotic postcranial bones from the Late Miocene of the present-day Moldova and propose a new genus and species for it-<i>Paratethyphoca libera</i>. It is distinguished in the presence of a supraorbital process of the frontal bone in its posterior portion, a long snout, a proportionally long humerus (88% of the skull length), a short deltoid crest of the humerus, and a low supraspinatus fossa of the scapula. We also suggest this taxonomic identification for other Paratethyan seals. Phylogenetic analysis placed <i>Paratethyphoca libera</i> among other stem Phocinae described so far from the Paratethys; however, its close relationship to a living hooded seal <i>Cystophora cristata</i> cannot be ruled out<i>.</i> Additionally, MCFFM V-150 showed tooth wear interpreted as a sign of suction prey capture strategy, shared by another Paratethyan seal <i>Monachopsis pontica</i> and the living bearded seal <i>Erignathus barbatus</i>.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00372-7.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"28"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12162803/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144303619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new pan-chelydrid turtle, <i>Tavachelydra stevensoni</i> gen. et sp. nov., from the lower Paleocene (early Danian, Puercan) Corral Bluffs Study Area in the Denver Basin, Colorado.","authors":"Tyler R Lyson, Holger Petermann, Salvador Bastien, Natalie Toth, Evan Tamez-Galvan, Sadie M Sherman, Walter G Joyce","doi":"10.1186/s13358-025-00375-4","DOIUrl":"10.1186/s13358-025-00375-4","url":null,"abstract":"<p><p>Isolated pan-chelydrid turtle shell fragments are common in Late Cretaceous and early Paleocene sediments across western North America, but more complete and associated specimens are rare, obfuscating our understanding of the group's early evolution. Here we describe a new genus and species, <i>Tavachelydra stevensoni</i>, of stem-chelydrid turtle from the early Paleocene of the Denver Formation (Danian, Puercan I and II) of Colorado based on complete shells, associated pelvic material, and referred cranial material. Our phylogenetic analysis places <i>T. stevensoni</i> as the immediate sister to crown chelydrids based on, among others, a purely ligamentous attachment of the plastron and carapace. The costiform process of the nuchal, an important character complex in chelydroid turtles, shows variation in either ending in peripheral II or III. The <i>T. stevensoni</i> material was mostly found in laminated fine-grained deposits, suggesting this taxon inhabited ponded-water environments. The referred cranial material shows broad triturating surfaces indicating a durophagous diet, further underscoring durophagy as an important feeding strategy during the early Paleocene.</p><p><strong>Supplementary information: </strong>The online version contains supplementary material available at 10.1186/s13358-025-00375-4.</p>","PeriodicalId":56059,"journal":{"name":"Swiss Journal of Palaeontology","volume":"144 1","pages":"46"},"PeriodicalIF":2.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12325531/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144801009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}