Craniomandibular osteology of <i>Macrocollum itaquii</i> (Dinosauria: Sauropodomorpha) from the Late Triassic of southern Brazil

Several new sauropodomorphs have been described in recent years, including the unaysaurid sauropodomorph <i>Macrocollum itaquii</i> (Late Triassic, Brazil). This study presents a detailed description of the craniomandibular anatomy of <i>M. itaquii</i> based on the holotype, a paratype and a newly referred specimen. A phylogenetic analysis using an updated dataset is performed to test a previous hypothesis regarding the affinities of this taxon and its potential influence in the phylogeny of Triassic and Early Jurassic sauropodomorphs. The taxon is supported as a member of Unaysauridae. This clade is recovered as the basal-most group within Massopoda rather than the sister group to Plateosauria. However, the position of <i>M. itaquii</i> (and unaysaurids) is likely to be highly labile due to specific, transitional aspects of its anatomy. The most recently discovered <i>M. itaquii</i> specimen, in conjunction with other newly discovered specimens, serve to elucidate the transition from slender basal sauropodomorphs to more robust derived members within this group.