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Since 1967, Palaeovertebrata has published original research on all aspects of vertebrate paleontology, including taxonomy, phylogeny, paleobiogeography, functional anatomy, biostratigraphy, paleoecology, and taphonomy.

 The new on-line version of Palaeovertebrata aims to meet a critical need for easier access to research outputs within the field of vertebrate paleontology, by providing the first "diamond open access" journal. All Palaeovertebrata articles are peer reviewed to ensure they meet the journal’s high quality standards. Palaeovertebrata’s primary objective is to accelerate the publication of high quality papers and provide immediate access to its published articles at no cost to its authors or readers. We anticipate that Palaeovertebrata will gain an Impact Factor in due course.
 

Designating a lectotype for Mesacanthus pusillus (Gnathostomata: Acanthodii)

Matthew Baron and Kevin Seymour

The early gnathostome genus Mesacanthus is well represented in both Lower Old Red Sandstone and Middle Old Red Sandstone assemblages of northern and central Scotland. This ‘acanthodian’ taxon is currently thought to comprise two valid species: M. mitchelli and M. pusillus. Although the whereabouts of the holotype of M. mitchelli (NHMUK PV P560) is known, the syntype material for M. pusillus has long been thought lost. Here we identify at least one specimen that formed part of the original syntype material for M. pusillus, albeit in a slightly different condition than when it was originally figured. This specimen is ROM 25872, which is here designated as the lectotype. A second specimen – ELGNM 1978.191.1 – could represent another of the syntype specimens, but poor preservation quality makes it impossible to be certain. 

Latest Early-early Middle Eocene deposits of Algeria (Glib Zegdou, HGL50), yield the richest and most diverse fauna of amphibians and squamate reptiles from the Palaeogene of Africa

Jean-Claude Rage, Mohamed Adaci, Mustapha Bensalah, Mahammed Mahboubi, Laurent Marivaux, Fateh Mebrouk and Rodolphe Tabuce

HGL50 is a latest Early-early Middle Eocene vertebrate-bearing locality located in Western Algeria. It has produced the richest and most diverse fauna of amphibians and squamate reptiles reported from the Palaeogene of Africa. Moreover, it is one of the rare faunas including amphibians and squamates known from the period of isolation of Africa. The assemblage comprises 17 to 20 taxa (one gymnophionan, one probable caudate, three to six anurans, seven ‘lizards’, and five snakes). Two new taxa were recovered: the anuran Rocekophryne ornata gen. et sp. nov. and the snake Afrotortrix draaensis gen. et sp. nov. The locality has also yielded the first confirmed anilioid snake, the first Palaeogene gymnophionan, and probably the first caudate from the Palaeogene (and possibly from the Tertiary) of Africa. The presence of a caudate at that time in Africa would be of particular interest; unfortunately, the available material does not permit a definitive identification. The fauna comprises Gondwanan and more specifically West Gondwanan vicariants, probably autochthonous groups and a Eurasian immigrant (assuming that the identification of the caudate is accurate). The fauna from HGL50 is clearly distinguished from the few other Eocene assemblages of Africa. However, if this results largely from differences in geological ages, geographic positions of the localities and mainly differences in environments took a part in the composition of the faunas. 

The digital endocast of Necrolemur antiquus

Arianna Harrington, Gabriel Yapuncich and Doug Boyer

The study of endocasts, or casts of the endocranial space, have played an important role in shaping understanding of mammalian, and particularly primate, brain evolution. Recently, the reconstructions of three-dimensional virtual endocasts from high-resolution computed tomography images have allowed for the visualization and quantification of endocasts in several Paleocene and Eocene primate species. Here we present the virtual endocast of MaPhQ 289 (informally known as the Montauban 9 skull), a specimen of Necrolemur antiquus Filhol 1873, a middle to late Eocene European primate of the family Microchoeridae. The virtual endocast of MaPhQ 289 reveals a lissencephalic surface morphology with expanded temporal poles and minimal overlap of the cerebellum or olfactory bulb by the cerebrum, which closely resembles the morphology of the endocast of its contemporary relative, Microchoerus erinaceus (Primates, Microchoeridae). MaPhQ 289 yields an endocranial volume (ECV) of 2.36 cm3, about 60% smaller than the volume of the most commonly cited ECV of N. antiquus. Thus, the size of the brain of N. antiquus relative to its body size is likely to be smaller than has been reported in previous literature, highlighting the importance of corroborating older ECV estimates with new evidence using 3-D imaging techniques. 

The skull of Tetraceratops insignis (Synapsida, Sphenacodontia)

Frederik Spindler

Tetraceratops insignis is known from a single, crushed skull from the Lower Permian of Texas. Its unique proportions and osteological details gained central meaning in the question of the origins of Therapsida since this early synapsid has been determined as the oldest and less derived therapsid. Apart from Tetraceratops, the ‘mammal-like’ Therapsida and their sister, the pelycosaur-grade Sphenacodontidae, are separated by one of the longest ghost lineages in tetrapod fossil record. However, the minor, though well justified critique faced insistent publication regarding the therapsid hypothesis. A carefull re-evaluation of the holotypic skull reveals that therapsid traits cannot be supported, including a rejection of the formerly supposed adductor shelf in the temporal fenestra. Increased understanding of ‘pelycosaur’ character variation underlines a haptodontine-grade or, less likely, sphenacodontid position for Tetraceratops. 

New material of “Eurysternidae” (Thalassochelydia, Pan-Cryptodira) from the Kimmeridgian of the Swiss Jura Mountains

Christian Püntener, Jérémy Anquetin and Jean-Paul Billon-Bruyat

The region of Porrentruy (Swiss Jura Mountains) is known for its rich and diverse assemblage of Late Jurassic coastal marine turtles (Thalassochelydia). Dominated by the “Plesiochelyidae”, this assemblage also includes representatives of the two other thalassochelydian groups, the “Thalassemydidae” and “Eurysternidae.” In this study, we present new shell-based material from Porrentruy referable to eurysternids. One specimen represents a juvenile individual or a relatively small taxon, and is notably characterized by a well fenestrated plastron exhibiting a wider than long central plastral fontanelle. Two other specimens are much larger and possibly represent the largest eurysternids known to date. The fourth specimen is characterized by a unique plastral morphology otherwise only known in very small juveniles. This is the first time this unique plastral morphology is known to persist in an adult or subadult. The new material described herein represents at least three distinct taxa, all of them probably new. However, we refrain from naming new species based on this incomplete material in order to avoid adding confusion to an already complex taxonomical situation. This study provides new insights into the great diversity of eurysternids during the Late Jurassic. 

Difficulties with the origin of dinosaurs: a comment on the current debate

Matthew G. Baron

The origin and early evolutionary history of the dinosaurs is a topic that has recently gone through a period of renewed interest and academic debate. For 130 years, one way of classifying the various dinosaur subgroups persisted as the accepted model, with increasing levels of research in the past quarter-century also providing evidence for the hypothesis that dinosaur origination occurred in the Southern Hemisphere, particularly in South America. It is, after all, from within the Late Triassic strata of countries like Argentina and Brazil that we get some of the very best early dinosaur specimens; many of these specimens are the earliest known representatives of some of the major dinosaur subgroups, such as the theropods and sauropodomorphs. However, some recent analyses have brought about a shift in terms of what is currently accepted and what is now disputed regarding the origin of dinosaurs – the Southern Hemisphere origination hypothesis was questioned (although this was based upon observations and not with quantitative analysis techniques), as has the shape of the dinosaur tree. Responses to the new hypothesis were numerous; many further supported a Southern Hemisphere point of origin. Whilst the interrelationships between the major dinosaur clades remains to be resolved, the current data does seem to comprehensively answer the question of where the dinosaurs first originated. However, it is arguable whether the current data that is being used in such palaeobiogeographical analyses is sufficient to provide an answer to the question of where specifically the dinosaur clade first appeared. This short communication urges a degree of caution about the current consensus and what steps may need to be taken to ensure that more meaningful results are produced in the future. 

The geologically youngest remains of an ornithocheirid pterosaur from the late Cenomanian (Late Cretaceous) of northeastern Mexico with implications on the paleogeography and extinction of Late Cretaceous ornithocheirids

Eberhard D. Frey, Wolfgang Stinnesbeck, David M. Martill, Héctor E. Rivera-Sylva and Héctor Porras Múzquiz

Ornithocheirid pterosaurs were the largest of the toothed pterodactyloids and had a worldwide distribution, although their fossil record is fragmentary, with the exception of the north-eastern Brazilian Crato and Santana Formations (Aptian, ?Albian, Early Cretaceous). With Istiodactylidae, they were also the only toothed pterosaurs that survived into the Cenomanian (Late Cretaceous), becoming extinct at the end of this period. Here we report on an ornithocheirid metacapus from the Late Cenomanian laminated limestone of north-eastern Mexico discovered about 120 km north-west of Ciudad Acuña, northern Coahuila at the south banks of Rio Bravo. The specimen comprises a fragmentary distal syncarpal, a crushed but complete metacarpal IV, two fragmentary preaxial metacarpals and a possible fragmentary terminal left wing finger phalanx. It represents the geologically youngest known ornithocheirid worldwide. We suggest that ornithocheirid pterosaurs may have become extinct because of massive sea level fluctuations during the mid to late Cretaceous that may have obliterated their breeding sites on coastal plains and low lying islands.