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Computed microtomography investigation of the skull of Cuvier's famous ‘opossum’ (Marsupialiformes, Herpetotheriidae) from the Eocene of Montmartre

2016; Oxford University Press; Linguagem: Inglês

10.1111/zoj.12495

1096-3642

Charlène Selva, Sandrine Ladevèze,

Amphibian and Reptile Biology

Two centuries ago, Georges Cuvier, the father of vertebrate palaeontology, described an almost complete skeleton of a small 'opossum' from the Montmartre Gypsum (late Eocene): Peratherium cuvieri. His description of the visible bones remains famous, as it was an unequivocal demonstration of his principle of correlation of parts. With the state-of-the-art technology of X-ray microtomography (computed tomography scanning), it is now possible to extend the investigation of the Cuvier's 'opossum', one of the most iconic specimens of the Muséum national d'Histoire naturelle (MNHN). Beneath the visible upper cheek teeth the skull is damaged and fragmented, but provides significant new data, with the most complete and informative structures being the paired petrosal bones. Comparisons with the didelphid Marmosa murina (Linnaeus, 1758) and three other fossil herpetotheriids [Amphiperatherium minutum Aymard, 1846, Herpetotherium cf. fugax Cope, 1873, and Peratherium elegans (Aymard, 1846)] suggest that dental features alone are not sufficient to discriminate between the different species, being based on highly variable, polymorphic features of the stylar shelf. The anatomy of the petrosal bone, which has yet to be described for P. elegans or A. minutum, reveals marked differences between P. cuvieri and H. cf. fugax, however, which brings into question the monophyly of Herpetotheriidae. Further investigation of petrosal characters for herpetotheriids would therefore shine new light on the phylogenetic affinities of Herpetotheriidae, in terms of both the relationships within the family and the position of Herpetotheriidae within Metatheria as a whole.