This paper provides the first geological and paleontological data of Yosobé and La Lobera, two Late Jurassic vertebrate localities; both localities are part of the marine

The Huehuetla quarry is a new fossiliferous site located near the town of the same name, into the region of Sierra Norte, northern Puebla, Mexico. This work represents the formal beginning of paleontological research on this site. This quarry occupies an area of about one hectare that is scarcely exploited with commercial purposes. The rocks rarely extracted in this site are slabs of nice jet-black carbonated shales with microscopic crystals of pyrite; which also are resistant, oily and stinky. The fossils recovered in these slabs belong to different marine vertebrate taxa, which include complete and articulated specimens as well as isolated bones. When it is preserved, the calcium phosphate of these bones is softened and filled with large calcite and pyrite crystals. Taxa represented in Huehuetla quarry constitute a peculiar assemblage that includes Nursallia aff. tethysensis, Tselfatia formosa, Goulmimichthys roberti, Hastichthys, indeterminate species of Enchodus and Clupeidae, as well as an indeterminate mosasaur. This is the first report of the pycnodontid N. tethysensis and of the dercetid Hastichthys fish all over America. This work provides evidence supporting the taxonomical validity of the species G. roberti. Based on its fossil content and lithology, it is determined that the fossil bearing strata of the Huehuetla quarry are part of the Turonian marine deposits of the Agua Nueva Formation.

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-IGM 9026 is a singular fossil collected at the beginning of the 20th century in an improperly documented site within the Tlaxiaco Basin, near to Tlaxiaco town, Oaxaca, Mexico. The age of the site was suggested as being early Cretaceous. This specimen is the holotype of Plesiosaurus (Polypticodon) mexicanus, which later was identified as a possible late Jurassic marine crocodylomorph of the family Metriorhynchidae, and consequently it was referred as ?Cricosaurus mexicanus. The present study provides a re-description of this fossil based on a microscopic analysis and the use of white and UV lights; these analyses led to the discovery of peculiar dental characters diagnostic of the genus Torvoneustes. This finding supports the re-classification of IGM 9026 under a new nominal combination as Torvoneustes mexicanus. Along the Tlaxiaco Basin, the fossil preservation mode and lithological composition observed in IGM 9026 only occur in the marine vertebrates recently discovered in Yosobé, a Kimmeridgian shale outcrop characterized by clay calcareous nodules that belong to the Sabinal Formation, near Tlaxiaco town. This peculiarity suggests that T. mexicanus could represent an additional element of the Kimmeridgian vertebrate assemblage recovered in this geological unit. The two nominal species of Torvoneustes were collected in Kimmeridgian marine deposits of England; hence, this finding expands the geographical distribution of Torvoneustes all along the Tethys Sea, from its Eastern/European to western/ Caribbean domains. Keywords:Torvoneustes, Plesiosaurus mexicanus, hispanic corridor, Kimmeridgian, Tlaxiaco Basin, Sabinal Formation. RESUMO -O exemplar IGM 9026 é um fóssil singular coletado no princípio do século 20 em um sítio pouco conhecido da Bacia Tlaxiaco, situado próximo a cidade de Tlaxiaco, Estado de Oaxaca, sul do México, cuja idade foi vagamente sugerida como do Eocretáceo. Originalmente, este único exemplar é holótipo do plesiossauro Plesiosaurus (Polypticodon) mexicanus. Mais tarde, ele foi identificado como um possível crocodilomorfo marinho do Jurássico Superior da família Metriorhynchidae, e portanto, foi referido como ?Cricosaurus mexicanus. O presente estudo proporciona uma nova descrição deste fóssil baseado em uma análise microscópica, uso de luzes brancas e UV, que levou à descoberta de caracteres dentários únicos neste exemplar, que coincidem com aqueles do gênero Torvoneustes. Este achado apoia a reclassificação de IGM 9026 a partir de uma nova combinação nominal como Torvoneustes mexicanus. Ao longo da Bacia de Tlaxiaco, o modo de conservação dos fósseis e a composição litológica observada em IGM 9026 somente se repetem nos vertebrados marinhos da Formação Sabinal, recentemente descobertos nas proximidades de Tlaxiaco. Esta peculiaridade sugere que T. mexicanus poderia representar um elemento adicional da associação de vertebrados fósseis do Kimmeridgiano da dita unidade geológica. As duas espécies nominais de Torvoneustes foram coletadas em jazimentos Kimeridgianos da Inglaterra, de f...

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