Crioceratites (Gerth, 1925) report with a description of C. tepehuaensis n. sp. from EastCentral México and some biostratigraphic appoints

Abstract

This manuscript reflects some efforts on the Otomí-Tepehua range, by reporting an outcrop in the east-central of Mexico with a new Crioceratites named C. tepehuaense. Although C. andinus Gerth, 1925, is similar to this new species among all of the known Crioceratites, it also presents enough specific differences in the ribs and spines to support C. tepehuaense. The fossil is assigned to the Berriasian/Valanginian with support of chronostratigraphic calpionellids previously reported: Tintinnopsella carpathica, T longa, Calpionellites darderi and Calpionellopsis oblonga, in contrast with reports of subfamily level that limit it from Lower Hauteriviano to Upper Aptian. The Berriasian/Valanginian lapse can be correlated with the Taraises Formation in Zacatecas, Mexico and it is discussed in the report of oil exploration wells of Pemex/IMP from the coastal planes of the Gulf of Mexico with regard to the Crioceratites, assigned to the Lower Tamaulipas Fm. Nevertheless, the taxonomic proximity with C. andinus, the finding of C. tepehuaense assigned to Lower Valanginian of the Mexican strata, opposes to the correlation with the Early Hauterivian of the cretaceous pacific South American coast. This suggests a differential dispersion of the Family and Genus. The chronostratigraphy boundary of Taraises Formation's strata transit from the Jurassic (Tithonian) and therefore still need precise delimitation; this finding contributes to the afore mentioned limit. Even more important, the richness of new genus and species of the interval Berriasian/Valanginian, presented before by Cantú-Chapa (2009), and now this new taxa, suggest high endemism with an entire new fauna for this interval and therefore open possibilities for the provincialism on the Caribbean Paleoprovince.