Géraldine Garcia

Dinosaur eggshells as biochronological markers in Upper Cretaceous continental deposits

Abstract European dinosaur eggshells are now well organized in a parataxonomic classification and can be used as reliable biochronological markers for Upper Cretaceous continental deposits. The Rognacian (Campanian–Maastrichtian) continental deposits of southern France can be divided into three successive associations of megaloolithidae taxa. A maximum in ootaxa diversity occurs in Upper Campanian deposits, followed by a decrease at the Campanian–Maastrichtian transition; this correlates with a climatic change recorded in the palynological floras. The stratigraphic distribution of the oospecies demonstrates that the ‘Rognac Limestone’ found in the west and east areas of the Arc basin is diachronic.

A NEW SPECIES OF STRUTHIOSAURUS (DINOSAURIA: ANKYLOSAURIA) FROM THE UPPER CRETACEOUS OF VILLEVEYRAC (SOUTHERN FRANCE)

Abstract A new species of the ankylosaur Struthiosaurus from the Upper Cretaceous (lower Campanian) of the Villeveyrac-Mèze Basin, southern France, is described from a partial skeleton that includes distal dorsal vertebrae, synsacrum and pelvic girdle. Struthiosaurus languedocensis, sp. nov. is a small-sized nodosaurid (less than 3 m length) characterised by distal dorsal centra that are very compressed laterally and hourglass in shape in ventral view; ischium directed immediately caudal from the acetabulum, with a robust shaft that does not taper distally and that is weakly curved in a caudoventral orientation. The synsacrum of S. languedocensis consists of ten co-ossified vertebrae, including five dorsals, four sacrals and a caudal. Among ankylosaurs, only Polacanthus foxii has a similar synsacral count, but there are significant differences in the pelvic structure between Struthiosaurus and Polacanthus. The presence of an ischium lacking a distinct nodosaurid-like ventral flexion appears to be diagnostic for the genus Struthiosaurus, as suggested by additional remains recovered from the upper Campanian of Laño (Iberian Peninsula). Current data suggests that Struthiosaurus is represented by different species in southwestern and central Europe.

The last polar dinosaurs: high diversity of latest Cretaceous arctic dinosaurs in Russia

A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous–Tertiary mass extinction event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10°C), but the climate was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result of temperature decline, caused or not by the Chicxulub impact.

Un nouveau gisement de vertébrés du crétacé supérieur à cruzy (hérault, sud de la France)

Abstract A new locality of Late Cretaceous (probably Early Maastrichtian) age near Cruzy (Herault, southern France) has yielded a varied vertebrate assemblage consisting of lepisosteid fish, albanerpetontid and anuran amphibians, pleurodiran and cryptodiran turtles, squamates (including varanoids), mesosuchian and eusuchian crocodilians, dinosaurs (abelisaurids, dromaeosaurids, titanosaurids and Rhabdodon) and enantiornithine birds. This fauna provides new evidence about the composition of Late Cretaceous European ecosystems.A new locality of Late Cretaceous (probably Early Maastrichtian) age near Cruzy (Herault, southern France) has yielded a varied vertebrate assemblage consisting of lepisosteid fish, albanerpetontid and anuran amphibians, pleurodiran and cryptodiran turtles, squamates (including varanoids), mesosuchian and eusuchian crocodilians, dinosaurs (abelisaurids, dromaeosaurids, titanosaurids and Rhabdodon) and enantiornithine birds. This fauna provides new evidence about the composition of Late Cretaceous European ecosystems.

RELATIONSHIPS BETWEEN EUROPEAN AND INDIAN DINOSAUR EGGS AND EGGSHELLS OF THE OOFAMILY MEGALOOLITHIDAE

Abstract Indian and French dinosaur eggshell oospecies belonging to the oofamily Megaloolithidae are compared and, of the fourteen Megaloolithidae oospecies previously described from the Late Cretaceous of India, seven are considered junior synonyms. Comparisons between nine oospecies from India and France reveal four groupings which show similarities between megaloolithids of these countries: (1) Megaloolithus microtuberculata, M. cylindricus, and M. padiyalensis; (2) M. mamillare and M. jabalpurensis; (3) M. siruguei and M. khempurensis; and (4) M. pseudomamillare and M. baghensis. Five oospecies from India have no French equivalents, whereas the oogenus Cairanoolithus is endemic to France. Updated synonymy Megaloolithus oospecies shows a total of nine distinct oospecies from India: Megaloolithus cylindricus, M. mohabeyi, M. padiyalensis, M. jabalpurensis, M. dholiyaensis, M. dhoridungriensis, M. khempurensis, M. megadermus, and M. baghensis. One oospecies, M. jabalpurensis, is common to India and South America and is considered here to be possibly a senior synonym of M. patagonicus. The similarities in egg taxa suggest close phyletic relationships, as well as the probable existence of a terrestrial connection of dinosaur fauna between India and Europe during the Cretaceous, and between the two gondwanan areas Patagonia and India.

First complete skulls of Elomeryx crispus (Gervais, 1849) and of Protaceratherium albigense (Roman, 1912) from a new Oligocene locality near Moissac (SW France)

ABSTRACT A new fossiliferous locality is reported from southwestern France (Moissac III) that yielded two skulls referred to the anthracotheriid Elomeryx crispus and the rhinocerotid Protaceratherium albigense, and an isolated rodent tooth. The anthracotheriid skull indicates a close relationship with E. borbonicus based on its cranial morphology. The rhinocerotid skull improves our knowledge concerning its anterior dentition, cranial morphology and proportions, and enables a more precise specific diagnosis. We suggest an early late Oligocene biochronological age (Mammal Paleogene European reference level MP25–26) for Moissac III, which is substantiated by the co-occurrence of P. albigense and of the theridomyid rodent Issiodoromys cf. paufflensis. The European stratigraphic range of E. crispus, so far restricted to the late Eocene-early Oligocene interval (MP18-MP22), extends up to the MP25–26, which in turn supports an origination of ‘Miocene bothriodontines’ from a European ancestor.

Nouvelles données sur les coquilles d'œufs de dinosaures Megaloolithidae du Sud de la France : systématique et variabilité intraspécifique

The Megaloolithidae oofamily, frequently found in the Late Cretaceous continental deposits of southern France, is the most diversified oofamily, with eight valid taxa. Several clutches newly discovered in the Arc syncline allow to identify a new oospecies, Megaloolithus microtuberculata, to emend the diagnosis of M. aureliensis, to synonymize Dughioolithus with Cairanoolithus and to discuss the definition of the discretispherulitic morphotype. For each oospecies, the individual morphological variability is established. The weight of erosion weathering and diagenesis on morphological variations is evaluated and it shows that a preliminary analysis of the preservation states is always necessary for the oomaterial determination.

Les oeufs de dinosaures du Cretace superieur du bassin de Villeveyrac-Meze (Herault, France); description d'une nouvelle ooespece de Prismatoolithus

The dinosaurian eggshell localities, found recently in the Villeveyrac-Meze basin allow to precise the datation of the continental levels overlaying the Villeveyrac Campanian series. They also provide information on the oospecies diversity in the Campano-Maastrichtian of southern France. Seven Megaloolithidae species which are already known in the Aix basin have been identified as well as a new prismatoolithid species, Prismatoolithus caboti.

Découverte du premier squelette presque complet de Rhabdodon priscus (Dinosauria, Ornithopoda) du Maastrichtien inférieur de Provence

Abstract The Vitrolles-Couperigne locality has yielded an almost complete skeleton of Rhabdodon priscus . Until now, this taxon was only represented by sparse and fragmentary remains. The flora and fauna associated to the R. priscus remains are briefly described. The position of the locality in the Late Cretaceous stratigraphy of Provence is discussed on the basis of dinosaur eggshell biostratigraphy. New data concerning some hitherto unknown anatomical features of the R. priscus permit discussion of its systematical position within the dinosaurs.

Ichthyosaurs from the French Rhaetian indicate a severe turnover across the Triassic–Jurassic boundary

Mesozoic marine reptiles went through a severe turnover near the end of the Triassic. Notably, an important extinction event affected ichthyosaurs, sweeping a large part of the group. This crisis is, however, obscured by an extremely poor fossil record and is regarded as protracted over the entire Norian–earliest Jurassic interval, for the lack of a more precise scenario. The iconic whale-sized shastasaurid ichthyosaurs are regarded as early victims of this turnover, disappearing by the middle Norian. Here we evaluate the pattern of this turnover among ichthyosaurs by analysing the faunal record of two Rhaetian localities. One locality is Autun, eastern France; we rediscovered in this material the holotypes or partial ‘type’ series of Rachitrema pellati, Actiosaurus gaudryi, Ichthyosaurus rheticus, Ichthyosaurus carinatus and Plesiosaurus bibractensis; a revised taxonomic scheme is proposed. The second assemblage comes from a new locality: Cuers, southeastern France. Both these assemblages provide several lines of evidence for the presence of shastasaurid-like ichthyosaurs in the Rhaetian of Europe. These occurrences suggest that both the demise of shastasaurids and the sudden radiation of neoichthyosaurians occurred within a short time window; this turnover appears not only more abrupt but also more complex than previously postulated and adds a new facet of the end-Triassic mass extinction.