Are Goniopholis crassidens and G. simus different species of crocodilians? New postcranial evidence solving a taxonomic riddle

The genus Goniopholis, as currently accepted, includes a considerable number of species, ranging from the Late Jurassic through Early Cretaceous of Europe, Americas and Asia. The type species, G. crassidens (Berriasian, England), was based upon a fragmentary postcranial skeleton and partial mandible (BMNH 3798-99). The putative association of a skull-roof with the type material cannot be demonstrated. Another specimen from the same strata, the isolated skull BMNH 41098, was made the type of a second species of Goniopholis, G. simus. However, relations between both materials remained dubious. As G. simus included skull material, G. crassidens was either largely ignored or considered a nomen dubium and G. simus served widely as a reference for the genus. Goniopholis material from the Berriasian of Germany includes a skull and postcranium (GZG.BA.0061), which allows direct comparison to the British Goniopholis specimens. The German skulls is remarkably similar to BMNH 41098, and all comparable postcranial elements show a very high degree of compliance with BMNH 3798-99. The pelvic girdle of both specimens, GZG.BA.0061 and BMNH 3798-99, share a potential autapomorphy of G. crassidens: the preacetabular edge of the ilium is narrow and dorsally excavated, lacking a distinct preacetabular process. Further, the first sacral rib articulates anterodorsally with a short acute anterior process of the ilium, here considered as not homologous to the preacetabular process of basal Crocodyliformes. Based on the data provided by the new German material, we regard G. crassidens as a diagnosable species, including G. simus as junior synonym, and restricted to the Berriasian of Southern England and Northwestern Germany. Contrary to previous referral in the bibliography, material from the Barremian through Aptian of England and Belgium and the Late Jurassic of Germany cannot be referred to G. crassidens or G. simus. This example illustrates the potential of postcranial morphology to provide meaningful systematic/taxonomic data in Crocodyliformes, particularly regarding the ilium morphology, which exhibits a high degree of interspecific variability.