A stegosaur tooth (Dinosauria, Ornithischia) from the Early Cretaceous of southwestern France

Abstract

International audienceThe spotty nature of the terrestrial fossil record for the Mesozoic hinders a more complete understanding of dinosaur diversity. For stegosaurs (Ornithischia), the plated dinosaurs, only a few and fragmentary remains are reported from the Early Cretaceous of Europe. A recent revision concluded that only a partial vertebra of the nomen dubium Craterosaurus (?Aptian, England) could be considered as stegosaurian. Here we report on a stegosaur tooth from the Early Cretaceous (Berriasian) Purbeckian deposits of Cherves-de-Cognac (Charente), southwestern France. This tiny tooth was examined in detail using microtomography. Comparisons being limited by the rarity of stegosaur tooth rows material (e.g., from the skull of the holotype of Stegosaurus stenops) and dental material, notably from Europe, we observed new material of cf. Stegosaurus armatus and Hesperosaurus mjosi from the Upper Jurassic Morrison Formation of Wyoming (USA). The tooth shows the most similarities to the Late Jurassic genera Stegosaurus and Hesperosaurus, but differs in having a distinctive downwardly arched (V-shaped) cingulum on the ?lingual face (maxillary tooth hypothesis). It is referred to as Stegosauria indeterminate, a medium-sized quadrupedal herbivore that inhabited an emerged land between the Armorican Massif and the Massif Central. This finding is the first evidence of a stegosaur from the Early Cretaceous of France and a welcome addition to the meagre European record of that time. In addition, it is the second stegosaurian tooth crown reported from Europe. The assemblage of ornithischians of Cherves-de-Cognac shares some similarities with that of the Early Cretaceous (Berriasian) of the Purbeck Limestone Group, southern England. The relative rarity of ornithischian osteological remains in both Purbeckian environments suggests that most of these dinosaurs were mainly inhabitants of inland terrestrial palaeoenvironments

New information about the stratigraphic position and age of the sauropodAragosaurus ischiaticusfrom the Early Cretaceous of the Iberian Peninsula

“…2010), yet this does not mean that they are exclusive to this formation. Indeed, they have been cited at various localities of the European Lower Cretaceous since last century (Galton & Upchurch, 2004; Billon-Bruyat, Mazin & Pouech, 2010). The presence of an isolated dermal spine at the site of La Canaleta in the lower part of the El Castellar Formation at Galve (Pereda Suberbiola et al .…”

Wear patterns and dental functioning in an Early Cretaceous stegosaur from Yakutia, Eastern Russia

“…The examined teeth from Teete can be assigned to the Stegosauria based on the following combination of features: the presence of a slightly asymmetrical crown, the presence of a well-developed and pronounced cingulum which is at about the same level on each crown surface, rounded and not sharply pointed tips of the denticles, and denticles that continue onto the adjacent surface of the crown to varying extent, appearing as semicircular, well-marked ridges in cross section (see stegosaurian dental features in [ 18 , 23 , 26 ]).…”

“…ungulatus from the Upper Jurassic of Portugal [ 31 ]. Later, Billon-Bruyat et al, 2010 [ 23 ] described a small wear facet on the apical tip of a tooth of Stegosauria indet. from the Early Cretaceous of France and similar facets for cf.…”

“…The cheek teeth of stegosaurs have a similar morphology but a slight asymmetry allows to distinguish the mesial and distal ends as well as maxillary from dentary teeth at least in Stegosaurus [18,[23][24][25]. The mesial part of the crown has fewer and larger marginal denticles and a convex outline in labial or lingual view.…”

“…developed and pronounced cingulum which is at about the same level on each crown surface, rounded and not sharply pointed tips of the denticles, and denticles that continue onto the adjacent surface of the crown to varying extent, appearing as semicircular, well-marked ridges in cross section (see stegosaurian dental features in [18,23,26]).…”