A New Sebecid from the Paleogene of Brazil and the Crocodyliform Radiation after the K–Pg Boundary

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.

New material of the ziphodont mesoeucrocodylian Iberosuchus from the Eocene of Languedoc, southern France

“…A sebecosuchian affinity was confirmed in Turner and Sertich (2010), and Iberosuchus and Bergisuchus were considered non-sebecid sebecosuchians in other phylogenetic analyses that included other baurusuchid and sebecid taxa Pol and Powell, 2011;Kellner et al, 2013;Pol et al, 2014). Therefore, Bergisuchus and Iberosuchus seem to belong to the Sebecosuchia (Sebecidae + Baurusuchidae) according to Pol et al (2012).…”

“…Their description provides a basis for comparing the genus Iberosuchus to other non-eusuchian ziphodont mesoeucrocodylians from Europe and Gondwana and although the new material does not add a sufficient number of characters for a phylogenetic analysis, its affinities are preliminary discussed with a focus on the Sebecosuchia (Sebecidae + Baurusuchidae sensu Pol et al, 2012) with which it has previously been allied Turner and Sertich, 2010;Kellner et al, 2013) as well as the Peirosauridae, which are allied to the Sebecidae under the phylogenetic hypothesis of Larsson and Sues (2007).…”

Revisão da família Baurusuchidae e seu posicionamento filogenético dentro do clado Mesoeucrocodylia

“…Até o que permite o conhecimento atual, os sebecídeos foram os únicos mesoeucrocodilos não-neossúquios a sobreviverem até o Cenozóico (Gasparini, 1984;Rossmann et al, 2000), e são conhecidas nove espécies sul-americanas, do Cretáceo ao Mioceno (Rusconi, 1946;Langston, 1965;Gasparini, 1984;Buffetaut & Marshall, 1991;Gasparini et al, 1993;Turner & Calvo, 2005;Paolillo & Linares, 2007;Pol & Powell, 2011;Kellner et al, 2014); pelo menos quatro espécies europeias, do Cretáceo e do Eoceno (Kuhn, 1968;Bunzel, 1871;Antunes, 1975;Rossmann et al, 2000;Company et al, 2005); e ao menos três espécies africanas, também do Cretáceo e do Eoceno (Buffetaut 1974;Buffetaut, 1989). O gênero Sebecus já apareceu como pertencente à irradiação Neosuchia (Andrade & Bertini, 2008;Sereno & Larsson, 2009), e também como pertencente à família Peirosauridae (Larsson & Sues, 2007;Sereno & Larsson, 2009;Young & Andrade, 2009;Andrade et al, 2011), basicamente devido a algumas características compartilhadas, como o quadradojugal participando do côndilo mandibular, a forma da fossa perinarial, e semelhanças dentárias.…”

Reptiles Extintos - Volumen en Homenaje a Zulma Gasparini

“…This increase in notosuchian diversity improved our knowledge on the distribution of this clade, both temporally and geographically. The biochron of most notosuchian clades is restricted to the Cretaceous, and ranges from the Aptian (Early Cretaceous) to the Maastrichtian (Late Cretaceous), although a lineage of notosuchians of debated affinities (Sebecidae) is recorded after the K/Pg extinction event, and survived until the Miocene in South America (Gasparini, 1972Kellner et al, 2014). O 'Connor et al, 2010;Sertich and O'Connor, 2014) and Madagascar (Buckley and Brochu, 1999;Buckley et al, 2000;Simons and Buckley, 2009).…”

“…Irrespective of their debated affinities, this distinct clade of notosuchians has its closest relatives in the Cretaceous and therefore must have been originated prior to the K/Pg boundary. This is the only notosuchian lineage that survived the mass extinction event (Gasparini, 1972Kellner et al, 2014) and subsequently became abundant during the Paleogene, especially in South America (Fig. 5.1-2).…”