Late Jurassic marine vertebrates from Tlaxiaco, Oaxaca State, southern Mexico

This paper provides the first geological and paleontological data of Yosobe and La Lobera, two Late Jurassic vertebrate localities; both localities are part of the marine deposits of the Tlaxiaco Basin, near Tlaxiaco, Oaxaca, Mexico. La Lobera may be included in Cerro de Titania, a historical invertebrate locality inaccurately described, whose Oxfordian-Early Kimmeridgian limestone and marl strata are informally known as "Caliza con Cidaris." La Lobera contains the typical "Caliza con Cidaris" fossils and the remains of a single fish attributable to the genus Scheenstia. Yosobe is a fossiliferous outcrop belonging in the Late Jurassic (Kimmeridgian-Tithonian) bituminous shale strata informally known as Sabinal formation. The fossil assemblage from Yosobe includes microfossils, plants, invertebrates, and vertebrates, many of which are totally or partially tridimensionally preserved within nodules. Yosobe is the most important vertebrate locality along the entire Tlaxiaco Basin due to a highly abundant and diverse grouping of fishes and reptiles. The fossil assemblage from Yosobe reported in this paper includes the first and most inclusive regional record of taxa such as the first North American Pleuropholidae fish, the first Mexican Jurassic Planohybodus shark, the most complete specimens of the pycnodont Gyrodus in Mexico and the Caribbean, ichthyosaurs, thalattosuchian crocodyliforms, turtles, and pliosaurids in a single locality at the Western Tethys Sea Domain and the Hispanic Corridor. Present and future descriptive and systematic studies on some fossils from these localities may have important paleobiogeographic and phylogenetic implications worldwide.