Saturday, May 31, 2014

[Paleontology • 2014] Aplestosuchus sordidus • An Additional Baurusuchid from the Cretaceous of Brazil with Evidence of Interspecific Predation among Crocodyliformes

Aplestosuchus sordidus 
Godoy, Montefeltro, Norell & Langer, 2014

Aplestosuchus sordidus preying on a sphagesaurid.  

Illustration: Rodolfo Nogueira. DOI: 10.1371/journal.pone.0097138

A new Baurusuchidae (Crocodyliformes, Mesoeucrocodylia), Aplestosuchus sordidus, is described based on a nearly complete skeleton collected in deposits of the Adamantina Formation (Bauru Group, Late Cretaceous) of Brazil. The nesting of the new taxon within Baurusuchidae can be ensured based on several exclusive skull features of this clade, such as the quadrate depression, medial approximation of the prefrontals, rostral extension of palatines (not reaching the level of the rostral margin of suborbital fenestrae), cylindrical dorsal portion of palatine bar, ridge on the ectopterygoid-jugal articulation, and supraoccipital with restricted thin transversal exposure in the caudalmost part of the skull roof. A newly proposed phylogeny of Baurusuchidae encompasses A. sordidus and recently described forms, suggesting its sixter-taxon relationship to Baurusuchus albertoi, within Baurusuchinae. Additionally, the remains of a sphagesaurid crocodyliform were preserved in the abdominal cavity of the new baurusuchid. Direct fossil evidence of behavioral interaction among fossil crocodyliforms is rare and mostly restricted to bite marks resulting from predation, as well as possible conspecific male-to-male aggression. This is the first time that a direct and unmistaken evidence of predation between different taxa of this group is recorded as fossils. This discovery confirms that baurusuchids were top predators of their time, with sphagesaurids occupying a lower trophic position, possibly with a more generalist diet.

Figure 1. Fossil crocodyliformes showing predator-prey interaction.
A, Aplestosuchus sordidus skeleton (LPRP/USP 0229a). Scale bar, 10 cm. B, Area highlighted in “a” with details of the abdominal content, including sphagesaurid remains (LPRP/USP 0229b). Scale bar, 5 cm. C, Reconstructed predator and prey. Reconstruction by Rodolfo Nogueira. Scale bar, 50 cm.

Systematic paleontology

Crocodyliformes Benton & Clark 1988  
Mesoeucrocodylia Whetstone & Whybrown 1983 
Baurusuchidae Price, 1945  

Aplestosuchus gen. nov.

Etymology. From Aplestos (Gr.), insatiate, gluttonous, and souchos (Gr.), after a creature of Egyptian zoomorphism.

Type species. Aplestosuchus sordidus gen. et. sp. nov.

Etymology. sordidus (L.), filthy; in reference to the manifest greedy behavior of the animal.

Holotype. LPRP/USP (Laboratório de Paleontologia, Universidade de São Paulo) 0229a is an articulated, nearly complete skeleton (Figure 1A).

Type locality. Buruti creek area, General Salgado municipality, São Paulo, Brazil (20°34′ 0″ S; 50°27′ 55″ W) (Figure 2). This is the same area yielded the type-specimens of four other crocodyliforms: Baurusuchus albertoi, B. salgadoensis, Armadillosuchus arrudai, and Gondwanasuchus scabrosus.

Godoy, P.L., Montefeltro, F.C., Norell, M.A. and Langer, M.C. 2014. An Additional Baurusuchid from the Cretaceous of Brazil with Evidence of Interspecific Predation among Crocodyliformes. PLoS ONE. 9(5): e97138. DOI:  10.1371/journal.pone.0097138