Dentes fósseis de arcossauros da formação feliz deserto (cretáceo inferior), Bacia de Sergipe-Alagoas

Abstract

The Cretaceous of the Sergipe-Alagoas Basin is updated by the abundance of fossiliferous marine deposits, predominantly invertebrate forms such as bivalves, cephalopods, gastropods and echinoderms. There are also records of microfossils, the most abundant among them being foraminifera and ostracods. The continental portions, on the other hand, have scarce records of plant remains, bivalves and scales generally attributed to the genus Lepidotes and, more recently, spinosaurids. The outcrops of the Feliz Deserto Formation originating from a deltaic lacustrine system have shown a great fossiliferous potential, presenting records of fossil vertebrates including spinosaurids and crocodyliform teeth. This study aimed to report, describe and identify fossil teeth of the Feliz Deserto Formation, located in the municipality of Japoatã (SE), collected between 2019 and 2020. For the identification of teeth, morphological features of the external and internal structures were observed when possible, such as, enamel texture, presence or absence of carina, presence or absence of flutes, plane of curvature, presence or absence of enamel, presence or absence of serrations. After collection, the teeth were described and classified based on comparisons made with studies already published in the specific literature and were separated into three distinct morphotypes. The morphological features of the assigned teeth were enough to safely identify some distinct taxa within the group of archosaurs that were identified as belonging to Crocodyliformes clade, the Spinosauridae family and the subfamilies Spinosaurinae and Baryonychinae. These classifications represent the first record of a Crocodyliformes for the Sergipe-Alagoas Basin, the second occurrence of a Spinosaurinae for the Feliz Deserto Formation and the first occurrence of a Baryonychinae in South America.