The Mosasaur Prognathodon (Reptilia, Mosasauridae) from the Upper Cretaceous of Belgium

The osteology of the mosasaurs Prognathodon solvayi and P. giganteus is extensively described for the first time. P. solvayi is known from the holotype IRSNB R33, a complete skull and partially preserved postcranial remains as well as from fragmentary material from specimens IRSNB R107 and IRSNB R108. P. giganteus is based wholly on the fragmentary cranial and postcranial remains of the type specimen IRSNB R106. Both species are compared with the North American taxa P. overtoni (KU 950, the holotype), P.? overloni (SDSM 3393), P. rapax (AMNH 1490),? Prognathodon (FMNH PR 165) and "Prognathodon" crassartus (AMNH 1562). P. sotvayi and P. giganteus are less similar to each other than are P. giganteus and SDSM 3393, referred to P. overtoni by RUSSELL (1967), especially with regard to overall shape and size. Because of the very fragmentary holotype material of P. overtoni comparisons with it are restricted. Characters critical in the classification of Prognathodon (such as dentition, zygosphenes, zygantra and haemal arches) are re-assessed. Re-evaluation of these characters induces changes in the generic assignments of the taxa within the Plioplatecarpinae. "Prognathodon" crassartus is reassigned to Plioplatecarpus. The status of FMNH PR 165, referred to Prognathodon by RUSSELL (1970) is questioned on the basis of conflicting diagnostic characters; it is a large plioptatecarpine mosasaur probably more closely related to Selmasaurus or Plioplatecarpus. Dollosaurus IAKOVLEV, 1901 is synonymised wiih Prognathodon. The ecology of Prognathodon and certain other mosasaurs of Belgium is discussed and comparisons are made with other aquatic vertebrates

A new Chinese specimen indicates that 'protofeathers' in the Early Cretaceous theropod dinosaur Sinosauropteryx are degraded collagen fibres

Alleged primitive feathers or protofeathers in the theropod dinosaur Sinosauropteryx have potentially profound implications concerning feather morphogenesis, evolution of flight, dinosaur physiology and perhaps even the origin of birds, yet their existence has never been adequately documented. We report on a new specimen of Sinosauropteryx which shows that the integumental structures proposed as protofeathers are the remains of structural fibres that provide toughness. The preservation in the proximal tail area reveals an architecture of closely associated bands of fibres parallel to the tail's long axis, which originate from the skin. In adjacent more exposed areas, the fibres are short, fragmented and disorganized. Fibres preserved dorsal to the neck and back and in the distal part of the tail are the remains of a stiffening system of a frill, peripheral to the body and extending from the head to the tip of the tail. These findings are confirmed in the holotype Sinosauropteryx and NIGP 127587. The fibres show a striking similarity to the structure and levels of organization of dermal collagen. The proposal that these fibres are protofeathers is dismissed

A new species of <i>Pluridens</i> (Mosasauridae Halisaurinae) from the upper Campanian of Southern Nigeria

The Upper Cretaceous of Africa has produced a diverse fauna of mosasaurs, including the highly specialized, long-jawed Pluridens. The type of Pluridens walkeri comes from the Maastrichtian Farin-Doutchi Formation of Niger, with a second, referred specimen coming from the Campanian section of the Campanian-Maastrichtian Nkporo Shale near Calabar, in southern Nigeria. Comparisons of this referred specimen with the holotype suggest that it represents a distinct and more primitive species. The Calabar jaw resembles P. walkeri in being long and narrow anteriorly with a shallow subdental shelf, and in having small, numerous, recurved teeth with medially positioned replacement pits. However, it lacks many of the derived features that characterize Pluridens walkeri, such as the extremely long and straight jaw, the extreme lateral protrusion and subcircular section of the dentary, strong transverse expansion of the dental thecae, and extreme reduction and increase in number of the teeth. The Calabar Pluridens is therefore referred to a new species, Pluridens calabaria. Following recent studies, Pluridens is considered to represent a highly derived member of the Halisaurinae. The marked differences between the Campanian and Maastrichtian species of the genus underscore the rapid pace of mosasaur evolution during the Cretaceous.</p

New insights on the systematics, palaeoecology and palaeobiology of a plesiosaurian with soft tissue preservation from the Toarcian of Holzmaden, Germany

© Springer-Verlag Berlin Heidelberg 2017. The attached document is the author’s submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it. The final publication is available at Springer via http://dx.doi.org/10.1007/s00114-017-1472-

The tooth, the whole tooth and nothing but the tooth: tooth shape and ontogenetic shift dynamics in the white shark Carcharodon carcharias

Ontogenetic dietary shifts are widespread across the animal kingdom, and often involve associated morphological changes in foraging phenotype. These changes may differ between sexes or vary between individuals, and are important factors in the ecology of species. While such factors have received much attention in terrestrial systems, they are much less well understood in marine taxa. The white shark Carcharodon carcharias is a marine apex predator that is accepted to provide a classic example of an ontogenetic dietary shift, with an associated change in tooth morphology from cuspidate to broad. Our results however, which include measurements obtained using a novel photographic method, reveal significant differences between the sexes in the relationship between tooth cuspidity and shark total length (TL), and a novel ontogenetic change in male tooth shape. Males exhibit broader upper first teeth and increased distal inclination of upper third teeth with increasing length, while females do not present a consistent morphological change. Substantial individual variation, with implications for pace of life syndrome, was present in males, and tooth polymorphism was suggested in females. Sexual differences and individual variation may play major roles in ontogenetic changes in tooth morphology in white sharks, with potential implications for their foraging biology. Such individual and sexual differences should be included in studies of ontogenetic shift dynamics in other species and systems

New ophthalmosaurid ichthyosaurs from the European lower cretaceous demonstrate extensive ichthyosaur survival across the Jurassic–Cretaceous boundary

Background Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. Methodology/Principal Findings Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval. Conclusions/Significance There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous

Morphological and Geochemical Evidence of Eumelanin Preservation in the Feathers of the Early Cretaceous Bird, Gansus yumenensis

Recent studies have shown evidence for the preservation of colour in fossilized soft tissues by imaging melanosomes, melanin pigment containing organelles. This study combines geochemical analyses with morphological observations to investigate the preservation of melanosomes and melanin within feathers of the Early Cretaceous bird, Gansus yumenensis. Scanning electron microscopy reveals structures concordant with those previously identified as eumelanosomes within visually dark areas of the feathers but not in lighter areas or sedimentary matrices. Fourier transform infrared analyses show different spectra for the feathers and their matrices; melanic functional groups appear in the feather including carboxylic acid and ketone groups that are not seen in the matrix. When mapped, the carboxylic acid group absorption faithfully replicates the visually dark areas of the feathers. Electron Paramagnetic Resonance spectroscopy of one specimen demonstrates the presence of organic signals but proved too insensitive to resolve melanin. Pyrolysis gas chromatography mass spectrometry shows a similar distribution of aliphatic material within both feathers that are different from those of their respective matrices. In combination, these techniques strongly suggest that not only do the feathers contain endogenous organic material, but that both geochemical and morphological evidence supports the preservation of original eumelanic pigment residue