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Saltillo, Mexico

Ifrim C.,Staatliches Museum fur Naturkunde | Ifrim C.,University of Heidelberg | Stinnesbeck W.,University of Heidelberg | Garza R.R.,Purcell 884 | Ventura J.F.,Santa Engracia 257
Journal of South American Earth Sciences

Few biostratigraphic data exist from the Parras and La Popa basins, mainly due to the absence of index fossils. This paper describes 19 ammonoid species from 15 genera and 1 nautilid from La Parra, southeastern Coahuila, Mexico. The assemblage consists of Tethyan [(Baculites ovatus, Brahmaites (Anabrahmaites) vishnu, Fresvillia constricta, Hauericeras rembda, Pachydiscus (P.) ex gr. neubergicus, Solenoceras reesidei, Tetragonites cf. superstes], cosmopolitan (Anagaudryceras politissimum, Desmophyllites diphylloides, Diplomoceras cylindraceum, Gaudryceras kayei, Phyllopachyceras forbesianum, Pseudophyllites indra), and cold water taxa [. Fresvillia teres, Hypophylloceras (Neophylloceras) surya, H. (N.) hetonaiense, Pachydiscus (P.) cf. egertoni]. Eutrephoceras sp. and Menuites juv. sp. were not determined to species level. A similar assemblage was recently described from the coeval Méndez Formation at Cerralvo, Nuevo León. Species endemic to North America, particularly the Western Interior Seaway, are absent at La Parra. The ammonoid assemblage and associated planktonic foraminifers allow for precise biostratigraphic assignation to the early Maastrichtian planktonic foraminiferal zone CF 5, and thus provide an important marker level for correlation of the lower Difunta Group. The new biostratigraphic data presented herein allow for the first time precise dating of the Cañon del Tule Formation of the Difunta Group. Their combination with existing sequence- and magnetostratigraphic data improve the correlation of the lower Difunta Group with time-equivalent lithostratigraphic units such as the Cárdenas Formation in Mexico. They also provide new insight into ammonoid migration patterns induced by sea-level changes. Baculites ovatus migrated into the La Popa Basin as a result of the sea-level highstand documented at La Parra. © 2009 Elsevier Ltd. Source

Zell P.,University of Heidelberg | Beckmann S.,University of Heidelberg | Stinnesbeck W.,University of Heidelberg | Flores-Ventura J.,Santa Engracia 257
Boletin de la Sociedad Geologica Mexicana

Here we present the first record of the belemnite Duvalia ex. gr. lata (Cephalopoda, Coleoidea) from Mexico. The unique individual, a well-preserved rostrum, was discovered in Early Cretaceous strata of the Sierra de Parras close to Viesca in southwestern Coahuila. Duvalia ex. gr. lata was previously known from the Mediterranean Tethys. Our report extends the paleogeographic distribution of Duvalia to the western hemisphere and supports the hypothesis that the Hispanic Corridor was open during the Early Cretaceous, allowing for marine faunal exchange and migration between the Gulf of Mexico and the European Tethys. Source

Ifrim C.,University of Heidelberg | Stinnesbeck W.,University of Heidelberg | Ventura J.F.,Santa Engracia 257
Journal of Paleontology

The cephalopods from Union y Progreso represent the first fossil assemblage described from the Parras Shale in Coahuila, Mexico. Pseudoschloenbachia (Pseudoschloenbachia) aff. P. (P.) mexicana (Renz, 1936), P. (P.) mexicana (Renz, 1936), Baculites haresi Reeside, 1927, and Menabites (Delawarella) vanuxemi (Morton, 1830) have a geographically restricted occurrence. Didymoceras juv. sp., Menuites juv. sp., Polyptychoceras juv. sp., Pseudoxybeloceras (Parasolenoceras) juv. sp., and Scaphites sp. ex gr. S. hippocrepis (DeKay, 1828) are represented by juveniles and could not be determined to species level. Desmophyllites diphylloides (Forbes, 1846) is the only long-ranging, cosmopolitan species described from this assemblage. Three new species are described: Eutrephoceras irritilasi n. sp., Hypophylloceras (Neophylloceras) arturoi n. sp., and Tetragonites silencioensis n. sp. The morphotype Baculites n. sp. is also inferred to be distinct. The faunal composition of this assemblage indicates a late early Campanian age. This assemblage shows a high degree of endemism. The causes for this endemism are currently unknown and difficult to assess. Nevertheless, the generic composition of the Union y Progreso ammonite assemblage suggests a short-term early Campanian endemic event. Copyright © 2013, The Paleontological Society. Source

Ifrim C.,University of Heidelberg | Stinnesbeck W.,University of Heidelberg | Espinosa B.,Benemerita Escuela Normal de Coahuila | Ventura J.F.,Santa Engracia 257
Journal of South American Earth Sciences

72 specimens of ammonites and the nautilid Eutrephoceras, collected from the upper Cretaceous Parras Shale at Saucedas in southern Coahuila, Mexico, are here assigned to twelve genera and fourteen species. The assemblage represents three to four upper Campanian biozones reaching from the Western Interior lower upper Campanian Exiteloceras jenneyi to the uppermost Campanian Tethyan Nostoceras hyatti biozone. Eutrephoceras irritilasi and Trachyscaphites sp. are endemic taxa, while Baculites taylorensis is restricted to the northern Gulf of Mexico Coast and E. jenneyi, Oxybeloceras crassum and Solenoceras elegans are Western Interior Seaway elements. Didymoceras donezianum is a southern Euramerican species, while Bostrychoceras polyplocum and N. hyatti occur throughout lower and middle latitudes. Diplomoceras cylindraceum and Phyllopachyceras forbesianum are cosmopolitan taxa with their main occurrences in the Maastrichtian; their record at Saucedas is the oldest of these species in North America. A clear paleobiogeographic signal is identified in the upper Campanian ammonite assemblages at Saucedas by a change from restricted towards geographically widespread faunas. This suggests gradual disappearence of faunal barriers which separated the Gulf Coast from the rest of the world. © 2015 Elsevier Ltd. Source

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