Baurusuchus

''Baurusuchus'' is an extinct member of the ancestral crocodilian lineage, which lived in Brazil from 90 to 83.5 million years ago, in the Late Cretaceous period. Technically, it is a genus of baurusuchid mesoeucrocodylian. It was a terrestrial predator and scavenger, about long and in weight. ''Baurusuchus'' lived during the Turonian to Santonian stages of the Late Cretaceous Period, in Adamantina Formation, Brazil. It gets its name from the Brazilian Bauru Group ("Bauru crocodile"). It was related to the earlier-named '' Cynodontosuchus rothi'', which was smaller, with weaker dentition. The three species are ''B. pachechoi'', named after Eng Joviano Pacheco, its discoverer, ''B. salgadoensis'' (named after General Salgado County in São Paulo, Brazil) and ''B. albertoi'' (named after Alberto Barbosa de Carvalho, Brazilian paleontologist). The latter species is disputed (see phylogeny section). Its relatives include the similarly sized '' Stratiotosuchus'' from the Adamantina Formation, and ''Pabweshi'', from the Pakistani Pab Formation.

Paleoecology

''B. salgadoensis'' is seen as a terrestrial predator, living in a hot and arid climate. The position of the external nares was unsuited for an amphibious lifestyle like in modern crocodilians and the snout and teeth are laterally compressed like in theropods. Both of this supports the terrestrial hypothesis. The hot environment hypothesis is based on the lifestyle of modern crocodilians and the stratigraphy of ''Baurusuchus''. ''B. salgadoensis'' was found in fine massive sandstones which are interpreted as a floodplain area in hot and arid climate. ''Baurusuchus'' was likely able to dig holes for finding water in dry seasons or, like modern alligators do, for thermoregulation. The occurrence of very complete skeletons in correlated stratigraphic levels supports this. Such a strategy would have made it less water-bound than most modern crocodiles, allowing it to live in more continental climate. The strongly bent pterygoids suggest a powerful bite and that ''Baurusuchus'' could close its jaw very quickly. The skull and tooth morphology indicates that the biting strategies of ''Baurusuchus'' were similar to a Komodo dragon which include ambushing the prey, biting it and pulling back the serrated, blade-like teeth. ''Baurusuchus'' likely played an important role in its ecosystem, competing with the abelisaurids for food.

Classification

''Baurusuchus'' is the type genus of the family Baurusuchidae, a family consisting of crocodilians with elongated and laterally compressed skulls. Other members of that family from the Cretaceous of South America include '' Stratiotosuchus'' and '' Cynodontosuchus'', but baurusuchids are also known from the Cretaceous of Asia (Pakistan) and the Tertiary of Europe.

A study in 2011 erected a new subfamily called Baurusuchinae. Seven diagnostic features for the group were described which include the moderate size and the broad frontals. The paper referred only ''Stratiotosuchus maxhechti'' and ''Baurusuchus'' to the subfamily, making ''Stratiotosuchus'' ''Baurusuchus closest relative so far. However, a study in the year 2014 referred a new species called ''Aplestosuchus sordidus'' to the subfamily, but supported a closer relationship of ''Baurususchus'' with ''Stratiotosuchus'' than with it. The species ''B. albertoi'' is an exception. The paper does not support its affiliation to ''Baurusuchus'' and views it as a close relative of ''Aplestosuchus''. This is the cladogram they presented:

Sources

* ''In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods'' by Nicholas C. Fraser and Hans-Dieter Sues
* ''The Osteology of the Reptiles'' by Alfred Sherwood Romer

References

{{Taxonbar, from=Q137262

Late Cretaceous crocodylomorphs of South America
Terrestrial crocodylomorphs
Baurusuchids
Fossil taxa described in 1945
Adamantina Formation
Prehistoric pseudosuchian genera