Dibothrosuchus elaphros, a crocodylomorph from the Lower Jurassic of China and the phylogeny of the Sphenosuchia

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Abstract
Much of a skeleton of Dibothrosuchus elaphros from the Lower Lufeng Group (Lower Jurassic) of Yunnan, China permits a detailed review of the anatomy and relationships of sphenosuchian crocodylomorphs. The skull is strongly built, akinetic, and monimostylic. The quadrate shows three dorsal processes that are firmly sutured to the skull roof and the braincase. The otic capsule is essentially crocodilian, and the tympanic pneumaticities are more elaborate than in extant forms. The animal possessed refined hearing ability and was probably vocal. The coracoid has an extremely elongated, posteriorly directed postglenoid process. The humerus bears an oval depression anteriorly near the head, and the radiale and ulnare are longer than the metacarpals. The limbs are long and slender, adapted for quadrupedal terrestrial gait. The estimated total length was 1.3 m. Phylogenetic analysis of 65 characters indicates the monophyly of the Sphenosuchia. Within the Sphenosuchia, Saltoposuchus (=Terrestrisuchus), Pseudhesperosuchus, Hesperosuchus, and Sphenosuchus are successively closer relatives to Dibothrosuchus. The Sphenosuchia, in turn, are the sister-group of Crocodyliformes.