CONICET | Buscador de Institutos y Recursos Humanos

The diagnosis of Dinosauria and interrelationships of the earliest dinosaursrelies on careful documentation of the anatomy of their closest relatives.These close relatives, or dinosaur ?precursors,? are typically onlydocumented by a handful of fossils from across Pangea and nearly all specimensare typically missing important regions (e.g., forelimbs, pelves, skulls)that appear to be important to help resolving the relationships of dinosaurs.Here, we fully describe the known skeletal elements of Asilisaurus kongwe,a dinosauriform from the Middle Triassic Manda Beds of the Ruhuhu Basinof Tanzania. The taxon is known from many disarticulated and partiallyarticulated remains and, most importantly, from a spectacularly preservedassociated skeleton of an individual containing much of the skull, pectoraland pelvic girdles, forelimb and hindlimb, and parts of the vertebral columnincluding much of the tail. The unprecedented detail of the anatomy indicatesthat Asilisaurus kongwe had a unique skull that was short and hadboth a premaxillary and dentary edentulous margin, but retained a numberof character states plesiomorphic for Archosauria, including a crocodylianlikeankle configuration and a rather short foot with well-developed metatarsalsI and V. Additionally, character states present across the skeleton ofAsilisaurus kongwe suggest it is more closely related to Silesaurus opolensisthan to dinosaurs; thus suggesting high homoplasy and parallel trendswithin Silesauridae and within lineages of early dinosaurs. The anatomy ofAsilisaurus kongwe and detailed description of early members of cladesfound outside Dinosauria are clearly needed to untangle the seemingly complexcharacter evolution of the skeleton within avemetatarsalians.

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