Carbonodraco lundi gen et sp. Nov., the oldest parareptile, from Linton, Ohio, and new insights into the early radiation of reptiles

Redescription of the holotype specimen of Cephalerpeton ventriarmatum Moodie, 1912, from the Middle Pennsylvanian (Moscovian) Francis Creek Shale of Mazon Creek, Illinois, confirms that it is a basal eureptile with close postcranial similarities to other protorothyridids, such as Anthracodromeus and Paleothyris. The skull is long and lightly built, with large orbits and a dorsoventrally short mandible similar to most basal eureptiles. Two specimens referred previously to Cephalerpeton cf. C. ventriarmatum from the approximately coeval Linton, Ohio, locality differ significantly from the holotype in cranial and mandibular proportions and tooth morphology. This material and an additional Linton specimen compare favourably to ‘short-faced’ parareptiles, such as Colobomycter and Acleistorhinus, and justify recognition of an acleistorhinid parareptile in the Linton assemblage. The new binomen is thus the oldest known parareptile

Digit and Ungual Morphology Suggest Adaptations for Scansoriality in the Late Carboniferous Eureptile Anthracodromeus longipes

A new skeleton of the exceedingly rare, late Carboniferous eureptile Anthracodromeus longipes (Carroll and Baird, 1972), reveals the presence of a reduced phalangeal count in the manus and pedes and uniquely recurved unguals. With these data, we quantitatively evaluate the locomotor ecology of Anthracodromeus using morphometric analyses of the phalangeal proportions, ungual curvature, and ungual shape. Our findings indicate that the anatomy of Anthracodromeus likely facilitated scansorial clinging to some degree via distally recurved unguals and increased surface area of the large manus and pes. This suggests that Anthracodromeus was among the earliest amniotes to show climbing abilities, pushing back the origins of scansoriality by at least 17 million years. It further suggests that scansoriality arose soon after the origin of amniotes, allowing them to exploit a wide range of novel terrestrial niches

A large brachyopoid from the Middle Triassic of northern Arizona and the diversity of brachyopoid temnospondyls from the Moenkopi Formation

Brachyopoids represent a diverse and late surviving temnospondyl group, lasting until the Early Cretaceous. Here, we report on brachyopoid material previously assigned to Hadrokkosaurus bradyi that represents a distinct brachyopoid taxon, characterised by a smaller number of large, robust mandibular teeth, a feature rarely observed in other temnospondyls. We also revisit an angular previously referred to Hadrokkosaurus potentially belonging to other temnospondyl taxa present in the Middle Triassic of North America. In light of the abundance of material of possible taxa distinct from Hadrokkosaurus, we express the need to re-examine previously collected specimens as new information changes the landscape of palaeontology. Parsimony analyses using exclusively mandibular characters recover the new brachyopoid taxon from the locality in a polytomy with Hadrokkosaurus and Vanastega at the base of Brachyopoidea, adding to a diversity of mandibular morphology of temnospondyls in the Middle Triassic of North America

Le sternum et l’interclavicule d’<i>Aelurognathus tigriceps</i> (Broom & Haughton, 1913) (Therapsida : Gorgonopsia), avec des commentaires sur l’évolution du sternum chez les Thérapsides

La compréhension de l’origine et de l’évolution du système respiratoire unique des mammifères dépend de notre connaissance des changements ostéologiques de l’appareil pectoral (scapulocoracoïde, cleithrum, clavicule, interclavicule, sternum) dans le registre fossile des synapsides. Chez les thérapsides non mammaliens, la documentation de cette anatomie est malheureusement incomplète, avec des groupes tels que les dinocéphales et les gorgonopsiens qui restent mal documentés. Nous présentons ici une description anatomique détaillée d’un sternum et d’une interclavicule articulés d’un spécimen bien préservé d’Aelurognathus tigriceps (Broom &amp; Haughton, 1913) provenant de la formation Madumabisa Mudstone supérieure du Lopingien, dans le bassin de Luangwa en Zambie. La morphologie sternale révèle de nouveaux détails anatomiques sur les sites d’attachement des côtes, montrant trois facettes distinctes, et une dépression précédemment non décrite sur la surface ventrale pour l’articulation avec l’interclavicule. Nous fournissons également une discussion préliminaire sur la variation morphologique de ces éléments au sein de Gorgonopsia et des Therapsida.Understanding the origin and evolution of the unique mammalian respiratory system hinges on our knowledge of the osteological changes in the pectoral apparatus (i.e., scapulocoracoid, cleithrum, clavicle, interclavicle, sternum) throughout the synapsid fossil record. Among non-mammalian therapsids, documentation of this anatomy is woefully incomplete, with groups such as dinocephalians and gorgonopsians remaining poorly documented. Here we provide a detailed anatomical description of an articulated sternum and interclavicle of a well-preserved specimen of Aelurognathus tigriceps (Broom &amp; Haughton, 1913) from the Lopingian upper Madumabisa Mudstone Formation, Luangwa Basin of Zambia. The sternal morphology reveals new anatomical details on the attachment sites for the ribs, showing three distinct facets, and a previously undescribed depression on the ventral surface for the attachment of the interclavicle. We also provide a preliminary discussion of the morphological variation of these elements both within Gorgonopsia and across Therapsida.</p

Antiquity of “Sail-Backed” Neural Spine Hyper-Elongation in Mammal Forerunners

Neural spine hyper-elongation in tetrapods is a unique morphological adaptation that creates a dorsal sail. While this extreme morphology has appeared several times in the evolutionary history of tetrapods, it was first experimented with by the non-mammalian synapsid paraphyletic group known as “Pelycosaurs,” famously represente

Diabloroter bolti, a short-bodied recumbirostran 'microsaur' from the Francis Creek Shale, Mazon Creek, Illinois

The Carboniferous (Pennsylvanian; 309-307 Mya) 'Mazon Creek' Lagerstätte produces some of the earliest tetrapod fossils of major Palaeozoic lineages. Previously, the Mazon Creek record of 'microsaurs' was known from a single specimen. However, the lack of key anatomy, such as the skull, precluded a confident taxonomic assignment, thus only a suggested affinity to the microbrachimorph 'microsaur' Hyloplesion was determined. Recently several new tetrapod specimens collected from Mazon Creek have come to light, of which some have recumbirostran 'microsaur' affinity. Here we describe a new genus and species of short-bodied recumbirostran, Diabloroter bolti, on the basis of a unique combination of autapomorphies. Both parsimony and Bayesian phylogenetic methods recover the new taxon in the Brachystelechidae clade, as sister to a clade including Carrolla and Batropetes. We determine Diabloroter to be the earliest known member of Brachytelechidae and thus establishing a Carboniferous origin of the family. We also provide an updated diagnosis for Brachystelechidae. Finally, we comment on the evolutionary trends in the clade, including dental adaptations for a proposed algivorous diet in derived clade members

New embolomerous tetrapod material and a faunal overview of the Mississippian-aged Point Edward locality, Nova Scotia, Canada

Embolomerous tetrapods, mid-to-large aquatic predators, form a major faunal constituent of Permo-Carboniferous tetrapod communities. Embolomeres are recognized by their distinct circular, bipartite vertebrae. Although traditionally classified as stem amniotes, the inclusion of embolomeres within the tetrapod crown group has recently been challenged. Despite the group’s phylogenetic uncertainty, embolomeres provide an important record of a long-lived tetrapod lineage, spanning ‘Romer’s Gap’ through to the Early Permian. Here we describe embolomerous tetrapod material that was collected in 1915 by W. A. Bell (CMN 10015, herein divided into CMN 10015A, B and C). The material, comprised of numerous disarticulated cranial and postcranial elements, was discovered near Sydney, Nova Scotia, as ex situ beach-float pertaining to a horizon within the Mississippian-aged Point Edward Formation. Of this material, a single left lower jaw of a proterogyrinid is identified, differing from previous embolomere remains from this site identified as ?Pholiderpeton bretonense. We also identify an anterior jaw fragment as a separate taxon from the proterogyrinid, indicating the presence of at least two embolomerous tetrapods in Bell’s collection. Other cranial and postcranial material cannot be directly associated with either jaw and are not diagnostic enough to assign to a specific taxon. Thus, the remaining material is referred to ‘Embolomeri indet.’ until more information is available. Additionally, we summarize the fauna of the Point Edward locality revealing a diverse aquatic Upper Mississippian ecosystem. Finally, the extensive embolomere material described here presents new data that can broadly address embolomere diversity throughout the Carboniferous.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

A large onychodontiform (Osteichthyes: Sarcopterygii) apex predator from the Eifelian-aged Dundee Formation of Ontario, Canada.

The Devonian marine strata of southwestern Ontario, Canada have been well documented geologically, but their vertebrate fossils are poorly studied. Here we report a new onychodontiform (Osteichthyes, Sarcopterygii) Onychodus eriensis n. sp. from the Dundee Formation (Eifelian-Givetian boundary, 390-387 Ma) of southwestern Ontario represented by two well-preserved onychodontiform lower jaws. The most complete specimen consists of a large (28cm), well preserved right jaw with most of the dentition present. The dentary has 50 teeth, not including the parasymphysial tusk whorl, which is poorly preserved but consists of at least three tusks. The anteriormost teeth of the dentary are also not complete, but the second dentary tooth is notably procurved. The posterior teeth are conical and approximately equal in size for much of the length of the tooth row. Onychodus eriensis n. sp. differs from the closely related contemporary species Onychodus sigmoides, and all other onychodonts, in that it has a strong dorsal curvature of the anterior dentary ramus, and marked anterior expansion of the dentary. An expanded phylogenetic analysis of Devonian onychodontiforms suggests that O. eriensis is closely related to Onychodus jandemarrai. The new material indicates that Onychodontiformes is more diverse than previously recognized, and that further analysis of vertebrate remains from southwestern Ontario will lead to additional insights into the diversity of Devonian sarcopterygians.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Varanopid from the Carboniferous of Nova Scotia reveals evidence of parental care in amniotes

Here we report on a fossil synapsid, Dendromaia unamakiensis gen. et sp. nov., from the Carboniferou