Redécouverte du « crocodile de Sheppey » de Georges Cuvier (Crocodilus delucii Gray, 1831) et signification du « monitor de Sheppey » (London Clay, Yprésien)

Abstract

Unpublished drawings made by Georges Cuvier in 1809, while visiting the collection of the Deluc family in Geneva, reveal the vertebrae of the crocodilian and the so-called “monitor lizard” or serpent of Sheppey that Cuvier briefly described in 1824 in the new edition of his Recherches sur les ossemens fossiles (Research on Fossil Bones). The crocodilian cervical vertebra, holotype of Crocodilus delucii Gray, 1831, was identified at the Natural History Museum in Geneva, where much of the Deluc collection is preserved. This specimen of historical interest does not make it possible to change the status of the species, which is considered as a nomen dubium, in view of the paucity of the diagnostic elements offered by an isolated vertebra. As for the second vertebra, first identified by Cuvier as that of a “monitor lizard”, and then as that of a snake, it appears to belong to the marine snake Palaeophis toliapicus Owen, 1841. This paper confirms that Cuvier is the first to have reported in a published work the presence of crocodilians and squamates in the London Clay Formation (Ypresian).