A complete skull of Allodaposuchus precedens Nopcsa, 1928 (Eusuchia) and a reassessment of the morphology of the taxon based on the Romanian remains

Abstract

ABSTRACT A new eusuchian skull from the Maastrichtian locality of Oarda de Jos in the southwestern Transylvanian Basin of Romania represents the best-preserved known specimen of Allodaposuchus precedens Nopcsa, 1928. This new fossil allows us to clearly characterize the skull morphology of A. precedens and to reject the idea, as recently suggested, that the taxon could be considered a nomen dubium. Parsimony analysis confirms earlier phylogenetic hypotheses based on the fragmentary holotype from the Maastrichtian of Valioara in Hat¸eg Basin (Romania), as well as on putative conspecific remains from approximately coeval localities in Spain and France: A. precedens is a non-crocodylian eusuchian. However, some relevant morphological traits differ from what was previously reported for this taxon: the external naris is large and anterodorsally directed; the lateral profile of the skull is not festooned in dorsal view; the suborbital fenestrae reach the eighth alveolus; the postorbital bar is not massive and inset from the jugal margin; the skull table is approximately planar or medially concave and does not markedly overhang the supratemporal fenestrae; the exoccipitals are not significantly involved in the basioccipital tubera. Because the condition of most of these characters was unknown in the holotype, the morphology of the taxon was previously evaluated on non-Romanian remains only. The morphological discrepancies between Romanian and western European fossils could suggest the presence of different taxa, possibly of infra-generic rank. Allodaposuchus and presumably Hylaeochampsa are the only eusuchians showing a laterally open cranioquadrate passage.