Junggarsuchus sloani, an Early Late Jurassic Crocodylomorph with Crocodyliform Affinities Open Access
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The holotype of Junggarsuchus sloani, from the early Late Jurassic of Xinjiang, China, consists of a nearly complete skull and the anterior half of an articulated skeleton, including the pectoral girdles, nearly complete forelimbs, vertebral column, and ribs. This taxon shares many features with a cursorial group of crocodylomorphs, known as ‘sphenosuchians’ whose relationships are poorly understood. However, it also displays several derived crocodyliform features that are not found among members of this group. A phylogenetic analysis corroborates the hypothesis that Junggarsuchus is closer to Crocodyliformes than Dibothrosuchus and Sphenosuchus, but not as close to crocodyliforms as Almadasuchus and Macelognathus, which includes extant crocodylians, and that the “Sphenosuchia” are a paraphyletic assemblage. Two other species of “sphenosuchians,” Dibothrosuchus elaphros and Sphenosuchus acutus, are hypothesized to be more closely related to Crocodyliformes while the rest of the ‘Sphenosuchia’ form several smaller groups and are largely unresolved. We find that Dibothrosuchus is not as closely related to crocodyliforms as Junggarsuchus, but also possesses several unique autapomorphies. We also report an elongate blade-like coronoid in Junggarsuchus that is also widely present in ‘sphenosuchians’.