Abstract

The anatomy and phylogenetic relationships of the Las Hoyas gobiosuchid (upper Barremian, La Huérguina Formation, Cuenca, Spain) are discussed on the basis of two fully articulated specimens. Phylogenetic analysis supports the monophyly of Gobiosuchidae, defined by the Las Hoyas taxon, Cassissuchus sanziuami, gen. et sp. nov., as the sister taxon of the Asian clade Gobiosuchus + Zaraasuchus. The family Gobiosuchidae is diagnosed by a large number of synapomorphies, such as the presence of extensively sutured palpebrals, ridges on the dorsal surface of the posterolateral region of the squamosal, a longitudinal ridge along the dorsolateral surface of the surangular, appendicular osteoderms, and closure of the supratemporal fenestra. Specimens attributed to Lisboasaurus estesi, a putative gobiosuchid, are evaluated and the taxon regarded as a nomen dubium. Cassissuchus sanziuami provides new evidence on the anatomy of the pectoral and pelvic girdles and the forelimb morphology in Gobiosuchidae. The phylogeny of basal Crocodyliformes supports the nested sequence of three clades: Protosuchidae, Gobiosuchidae, and ((Shantungosuchus + Sichuanosuchus) + Shartegosuchidae), but their interrelationships are only partially solved. The early evolution of Crocodyliformes is further characterized by the high number of phenotypic specializations, many of which are related to the dermal skeletal overgrowth of the temporal region, palpebrals, and osteoderms.