The phylogenetic position of Afromimus tenerensis Sereno, 2017 and its paleobiogeographical implications

Abstract

Afromimus tenerensis Sereno (2017) was recently described on the basis of an incomplete skeleton coming from the Lower Cretaceous of Niger. The specimen was originally identified as a basal ornithomimosaur. This clade of dinosaurs was abundant in North America, Europe, and Asia, but virtually unknown in Gondwana and thus its presence has deep palaebiogeographical implications. However, a critical review of the homologies proposed in the original description indicates instead that it may belong to Abelisauroidea. It shares with the latter clade: tibia with fibular crest continuous with the proximal end, large elliptical scar on posterior tibia, relatively low ascending process of the astragalus which is subrectangular in contour and is fused to fibula, a large iliofibular tubercle of fibula, pedal phalanx lacking flexor tubercle, having a lateral bump, and “V" shaped lateral furrows, distal caudal vertebrae with excavated fossae for prezygapophyses, and chevrons anteroposteriorly narrow with fused pedicels. Phylogenetic analysis here performed resulted in the inclusion of Afromimus within Abelisauroidea, being probably related to the Noasauridae. Afromimus shows several unique features sustaining that it is a valid taxon. The present contribution indicates that there is no incontrovertible evidence of ornithomimosaurs in Gondwana.