Late Cretaceous vertebrate diversity at Fazenda Três Antas Site (Campina Verde-MG): Adamantina Formation at Triângulo Mineiro

AGUSTIN MARTINELLI; MARINHO, THIAGO S.; FABIANO IORI; LUIZ CARLOS RIBEIRO

Congreso; XXV Congresso Brasileiro de Paleontologia; 2017

The Fazenda Três Antas site (FTA; Campina Verde Municipality, Triângulo Mineiro) was first known due to the discovery of several specimens of the baurusuchid Campinasuchus dinizi. Continuous field works at this locality and surrounding areas have provided a noticeably taxonomic diversity of vertebrates still in stage of study. At the FTA there were discovered a partial crocodyliform egg from the Campinasuchus?s level, a putative lens with abundant fish remains and an abelisaurid tooth, and the first occurrence of the genus Caipirasuchus (Notosuchia, Sphagesauridae) in Minas Gerais State. Near this latter specimen, a cluster of 5 eggs was also found. These fossils came from Adamantina Formation (Late Cretaceous, Bauru Basin), consisting predominantly by red sandstones deposited by fluvial streams. The abundance of fish remains is conspicuous, being a monotypic assemblage of Lepisosteiformes. They are represented by jaws, skull and appendicular fragments, vertebrae and scales. The jaws are antero-posteriorly short and medially convex as seen in Atractosteus and Cuneatus and the subopercular bears a denticulated distal edge as in A. falipoui from the Lower Cretaceous of Africa. The specimens at FTA possibly represent a new species of Atractosteus in continental settings of the Bauru Group. The specimen of Caipirasuchus sp. comes from the lower level of the exposed sequence at FTA and is not associated to Campinasuchus. The new specimen includes an almost complete skeleton with a total body length of 70 cm. It has a combination of features that does not allow its inclusion in any of the hitherto known species. Those differences are: last two maxillary teeth located posterior to anterior edge of infraorbital fenestra, elongated lateroventral maxillo-jugal suture ? about ½ the anteroposterior maxillar length?, large facial process of premaxilla, contact between posterior crest of quadrate and posterior end of squamosal forming an almost 90° flaring roof of the squamosal. These features are interpreted as of taxonomic value and this specimen represents the fourth species of the genus. Field works at the west portion of Triângulo Mineiro are providing new clues on the diversity of the Late Cretaceous communities of the Bauru Group, and at present, this assemblage is the most diverse of the Adamantina formation at Minas Gerais