Endocranial anatomy of a marine Crocodylomorpha (Thalattosuchia): a preliminary study

HERRERA Y.

Munich

Congreso; 17th Annual Meeting of the Gesellschaft für Biologische Systematik; 2016

Bayerische Staatssammlung für Paläontologie und Geologie

Thalattosuchians were Mesozoic marine crocodylomorphs known from deposits of the Lower Jurassic through the Lower Cretaceous, and without close extant relatives. Thalattosuchia comprises an assemblage of basal forms, the teleosaurids (shallow coastal forms), and the fully pelagic forms known as the Metriorhynchidae. Their fossil record is abundant, and most of them have been recovered from marine deposits in Europe and South America. Despite their abundant fossil record, the phylogenetic placement of Thalattosuchia in crocodyliform systematics is still debated. During the last few decades digital techniques to study fossils have been used to visualize the internal morphology of the skull, and to generate virtual cast of the internal cavities and/ or bones. Neuroanatomical studies in Thalattosuchia are scarce, even though they are important for two main reasons: they provide further insights into the palaeobiology of these animals and therefore contribute to understand secondary marine adaptations; and, second, internal anatomical exploration provides features of potential phylogenetic value. As part of a project that includes the internal anatomical exploration of several specimens or Thalattosuchia and other crocodyliforms, I studied the teleosaurid Steneosaurus bollensis (SNSB-BSPG 1984 I 258) based on micro-CT scanning. Results show that some endocraneal features that were believed to be exclusive to Metriorhynchidae are present in Steneosaurus bollensis. Their presence in this taxon suggests that certain endocraneal features were more widely distributed within Thalattosuchia and not restricted to Metriorhynchidae. The preliminary information obtained here will be useful to expand character information/sampling related to the braincase anatomy of marine crocodylomorphs.