Abstract
A new crocodyliform, Sahitisuchus fluminensis gen. et sp. nov., is described based on a complete skull, lower jaw and anterior cervical vertebrae collected in the São José de Itaboraí Basin of Rio de Janeiro, Brazil. The specimen is one of the best preserved crocodyliforms from Paleocene deposits recovered so far and represents a sebecosuchian, one of the few clades that survived the Cretaceous-Paleogene biotic crisis. The new taxon is found in the same deposit as an alligatoroid, a group that experienced large diversification in the Paleogene. The sebecosuchian record suggests that after the Cretaceous-Paleogene biotic crisis, the less specialized members of this clade characterized by a higher number of teeth compared to the baurusuchid sebecosuchians survived, some having terrestrial habits while others developed a semi-aquatic life style (e.g., Lorosuchus). Starting in the Eocene, sebecid sebecosuchians became specialized with a more accentuated oreinirostry as observed in Sebecus and in Langstonia, but not showing the typical reduced dentition developed by the Cretaceous baurusuchid sebecosuchians. The basal position of Barinasuchus arveloi, a high-snouted Miocene sebecid, indicates the occurrence of an independent lineage sometime after the K-Pg biotic crisis that developed accentuated oreinirostry, suggesting a more complex history of the post-K-Pg crocodyliform radiation.
Highlights
Crocodyliforms are worldwide distributed in tropical and subtropical regions in relative low numbers and diversity, consisting of 24 to 30 species (e.g. [1])
Phylogenetic Analysis In order to access the phylogenetic position of Sahitisuchus fluminensis gen. et sp. nov., a phylogenetic analysis was performed using the data matrix published by Pol et al (2012) [17]
Specific name fluminensis is a latinization of fluminense, designation of citizens born in the Rio de Janeiro State
Summary
Crocodyliforms are worldwide distributed in tropical and subtropical regions in relative low numbers and diversity, consisting of 24 to 30 species (e.g. [1]). Crocodyliforms are worldwide distributed in tropical and subtropical regions in relative low numbers and diversity, consisting of 24 to 30 species During the Cretaceous, the diversity of those reptiles was much higher and they occupied several distinct niches. [5,6]), there are only a limited number of Paleocene specimens described so far, most of which are fragmentary and poorly preserved [4,7,8,9]) This contrasts with the high abundance of Late Cretaceous crocodyliforms, in Brazil, which is even higher than in other Gondwanan areas
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