The genus Montastraea (Cnidaria, Scleractinia) from the Cretaceous in the Araripe Basin, Northeastern Brazil

The Araripe Basin, located in the Northeast Region of Brazil and spanning portions of Ceará, Pernambuco, and Piauí states, is one of the most emblematic sedimentary basins in the country due to its abundance of fossils and the richness of its paleobiota. Concretions can be found in the western region, including Araripina and Trindade in Pernambuco and Caldeirão Grande and Simões in Piauí. During expeditions in Simões, Piauí, we identified the first fossil coral from the Romualdo Formation (Lower Cretaceous, Santana Group), classified within the genus Montastraea Blainville, 1830. This significant discovery advances our understanding of the region's paleoenvironmental history and biodiversity. Although Montastraea is relatively common in the Tethys Sea, this represents its southernmost occurrence to date. This study provides descriptive, morphometric, and phylogenetic data for the specimen, reinforcing the Tethyan affinities of the Araripe biota. The presence of this fossil coral suggests that a shallow, tropical marine environment adapted to clear, likely warm, waters.
Keywords: Fossil, Coral, Romualdo Formation, Paleobiogeography

位于巴西东北部地区，横跨塞阿拉、佩德罗阿兰达库和皮奥伊等州的部分区域，阿拉里佩盆地因其丰富的化石资源及古生物群系的丰富多样性，成为该国最具代表性的沉积盆地之一。在盆地西部区域，如佩德罗阿兰达库的阿拉里皮纳和特兰达德，以及皮奥伊的卡尔德亚尼奥格兰德和西莫埃斯等地，均发现了结核。在皮奥伊的西莫埃斯地区进行的探险活动中，我们首次发现了来自罗慕阿尔多组（下白垩纪，桑塔纳群）的化石珊瑚，该化石珊瑚被归类于蒙塔斯特雷亚属（Montastraea Blainville, 1830）。这一重大发现推进了我们对该区域古环境历史和生物多样性的理解。尽管蒙塔斯特雷亚在泰瑟斯海相对常见，但这标志着其迄今为止最南端的分布。本研究为该标本提供了描述性、形态计量学和系统发育数据，进一步证实了阿拉里佩生物群的泰瑟亚联系。该化石珊瑚的存在表明，一个浅水、热带海洋环境适应了清澈、可能温暖的水域。关键词：化石、珊瑚、罗慕阿尔多组、古生物地理学