Mega fossils of conifers of the upper triassic and the upper cretaceous of mexico and general considerations on the mesozoic conifers of mexico
Universidad Nacional Autonoma de Mexico Instituto de Geologia Revista 4(2): 111-124
The megafossils collected between 1970 and 1979 from the Santa Clara Formation (Upper Triassic, Sonora) and the Olmos Formation (Maestrichtian, Coahuila) enhanced the knowledge of the fossil conifers of Mexico. In the Sonoran Triassic, they are represented by Elatocladus, Podozamites, (Pelourdea and Desmiophyllum). In the Coahuilan Cretaceous, Aachenia knoblochi, Brachyphyllum macrocarpum, Geinitzia sp., Kobalostrobus olmosensis, Sequoia cuneata and Raritania cf. gracilis were found. In the taphoflora of the Early and Middle Jurassic of Mexico, only a few conifer megafossils were recorded. These 3 fossil floras are associated with coal beds, which indicate similar sedimentary environments. Under these conditions allochthonous plant fossils are a component of minor importance. In addition, the available paleogeographic information indicates little elevation above sea level, and probably warm climates for the 3 floras. An attempt is made to explain the relative frequency and diversity of the conifers in the 3 taphofloras.