Huerta-Vergara, Alma , Calvillo-Canadell, Laura , Cevallos-Ferriz, Sergio , Silva-Pineda, Alicia .
Description and identification of Aptian-Cenomanian Pinaceae and Podocarpaceae from El Chango, Chiapas, Mexico.
Conifers are a group of seed plants included within the gymnosperms, which were abundant and dominant during the Mesozoic. In Mexico the fossil record of the group is little known and studied, although its presence has been documented since the first half of the last century. In Chiapas, Mexico, material representing part of the history of some groups of conifers has been recently collected, including families Pinaceae and Podocarpaceae, in which this study focuses is. The fossiliferous locality El Chango in the southeastern Mexico, belongs to the Sierra Madre Formation, known by the presence of different taxa preserved in its Aptian-Cenomanian sediments, including fishes, arthropods (mainly crustaceans), cephalopods (ammonites) and plants (gymnosperms predominating over angiosperms). Among the plant material vegetative with affinity to Pinaceae include needle-like leaves, short and long twigs with spiral phyllotaxy, as well as male and female cones. In particular a structure is similar to fascicles of extant Pinus. Material with affinity to Podocarpaceae is based solely on impressions of flat, elongated, linear shaped leaves with entire margins, with parallel venation. Although this study focuses on forms from El Chango, Chiapas, it is important mention two specimens recently collected in the state of Sonora that enrich the knowledge of Late Campanian- Maastrichtian Pinaceae. Both specimens have an axis with spirally arranged needles and leaf scars, but a sample also has a female cone, with well preserved ovuliferous scales and bract-like projections, suggesting that this is a compound cone. This material is similar to that described by Weber in the 70's as Pinaceae from the Cretaceous of Coahuila. The description and identification of new material provides historical and geographical information relevant to families Pinaceae and Podocarpaceae in the lower regions of North America, whose history has yet to be elucidated.
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1 - Facultad De Ciencias, UNAM, Biología, Calle 2 #34, Col. Del Maestro; Azcapotzalco, México, D.F., N/A, 02040, Mexico
2 - Instituto De Geología, UNAM, Circuito De La Investigación, Ciudad Universitaria, Coyoacan, N/A, 04510, Mexico
3 - Instituto De Geología, UNAM, Department Of Palentology, Ciudad Univwersitaria, Coyoacan, MEXICO D.F., N/A, 01900, Mexico
4 - Instituto de Geolgía, UNAM, Paleontología, Ciudad Universitaria, C, México D.F., 04510
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Monday, July 9th, 2012
Time: 2:15 PM