BAURUSUCHID CROCODYLIFORMS BEYOND THE THEROPOD MIMICRY

"As soon as the first baurusuchid was described, several theropodomorph features have been recognized throughout its skeleton, most related to a parasagittal gait and fully terrestrial habits that enables the larger species as top predators. It includes compressed and serrated teeth with pseudoampulla (like the ampulla in theropod teeth), rostrum with high profile, binocular orbits, appendicular muscle insertions increasing protractor vector and reducing adduction/abduction and torsional moment, among other. The hypothesis of competition between theropods and Baurusuchidae gained more support over time, when more and most complete specimens were studied. Heretofore occurring only at Santonian-Campanian deposits of the Neuquén and Bauru basins, the following pattern is noteworthy: the scarcer and smallest baurusuchids (skull length until 150 mm) occurs where several small to medium theropods are known: the Bajo de la Carpa Formation, with the tiny _Wargosuchus_ and _Cynodontosuchus_ and a medium-sized unnamed baurusuchids, all represented by fragmentary remains contemporary of _Tratayenia_, _Achillesaurus_, _Alvarezsaurus_, _Velocisaurus_ and _carnotaurine abelisaurs_ among non-avian theropods. Instead, after almost a century of prospection, no more than some isolated theropod teeth and putative fragmentary bones were found in the Adamantina Formation, where a far more diverse baurusuchid record is known: _Gondwanasuchus_, _Campinasuchus_, _Pissarrachampsa_, _Aspletosuchus_, _Baurusuchus pachecoi_, _B. albertoi_, _B. salgadoensis_ and _Stratiotosuchus_, represented by dozens of specimens well preserved, and some surpassing 200 kg in body mass (skull and femoral length between 300 and 500 mm), pointing to a larger biomass in that biocenosis available to be fossilized. Extinct along the Campanian, no Baurusuchidae occur in the overlaying Marília Formation (Maastrichtian), where theropods become more common, including abelisaurid and maniraptoran. The diversity of Peirosauridae crocodyliforms, titanosaur sauropods, besides Ostracoda and Bivalvia, did not change significantly from Adamantina to Marilia times. Therefore, we consider that the high diversity and abundance of baurusuchid contrasting with Theropoda among predators recorded in the Adamantina Formation is not a preservational artefact, but a real condition of that cretaceous ecosystem. Other interpretations already proposed disregard the faunal turnover and fossil record heterogeneity between Adamantina and Marilia formations, just suppose specific environmental condition to each taxon (lowland X highland) or generalizing a behavioural bias to preservation, visions that remain as narratives only. [*FAPEMIG; **CNPq, ***SESu/MEC]