From flying reptile to marine turtle: the « pterodactyl » from the Chalk of Lezennes-lez-Lille

In 1874,Charles Barrois reported a pterodactyl tibia,from the White Chalk (?Craie blanche?) which was then exploited in underground quarries at Lezennes (now in the suburbs of Lille). He referred it to Pterodactylus giganteus,a species from the English Chalk. Although no detailed description or illustration was provided,the occurrence of a pterodactyl in the Coniacian Lezennes Chalk was repeatedly mentioned in papers on local geology,as well as in lists of French pterosaurs.A re-examination of the specimen (Musée d'Histoire Naturelle de Lille,MGL 4158) shows that it is an elongate,more or less cylindrical non-pneumatised bone with poorly differentiated articular ends,which bears no resemblance to pterosaur tibia,nor to any other element of a pterosaur skeleton.Comparisons reveal that the so-called pterosaur tibia from Lezennes is in all likelihood a phalanx of a marine reptile. Among Late Cretaceous marine reptiles,plesiosaurs have proportionally much shorter phalanges. In mosasaurs,the phalanges are elongate but more hourglass-shaped than the specimen from Lezennes. The greatest resemblances seem to be with phalanges of marine turtles,which show a comparable degree of elongation and proximal and distal expansion. Incidentally,a turtle shell is known from the Lezennes Chalk.

Disciplines : Paléontologie. Paléobotanique. Paléozoologie,Climatologie
Mots-clés : analyse,biodiversité,biogéographie,climatologie,fossile,paléobiologie,paléoenvironnement,paléontologie,réchauffement climatique
Type de document : image en mouvement
Type de ressource : lecture
Niveau : higher education,master
Publics visés : learner
Auteurs ou éditeurs : Eric Buffetaut,Université Lille 1