O gênero Montastraea (Cnidaria, Scleractinia) do Cretáceo, Grupo Santana, nordeste do Brasil

Abstract

Among the sedimentary basins in Brazil, the Araripe Basin is one of the most emblematic due to its quantity of fossils and exuberant paleobiota. It is located in the Northeast region of the country and occupies portions of the states of Piauí, Pernambuco and Ceará. In a recent paleontological incursion carried out in the Araripe Basin, more precisely in the municipality of Simões (western border of the state of Piauí), a sample of fossil coral from the Romualdo Formation (Lower Cretaceous, Santana Group) was collected, here described as a specimen belonging to the genus Montastraea Blainville, 1830, and later listed in the scientific collection of the Picos Paleontology Laboratory of the Federal University of Piauí. The genus is relatively abundant in the Tethys Sea; however this is the southernmost occurrence to date. This study presents descriptive, morphometric and phylogenetic data from the specimen and reinforces the Tethyan affinities of the Araripe biota. In comparative analysis with other specimens of Cretaceous scleractinian corals, Montastraea sp. proved to be different from the other species of the genus due to the small diameter of the colony, the hemispherical shape, the intermediate diameter of the corallites and the distances between the columellae. Despite all these differences, it was preferable not to interpret it as a new species, among other factors, due to the absence of more specimens and possible deformities of characteristics suffered during the taphonomic process. The presence of a fossil coral in the basin indicates a shallow tropical marine biota adapted to clear and probably warm waters.