Upchurch, Garland , Mack, Greg , Estrada-Ruiz, Emilio , Wheeler, Elisabeth , Parrott, Joan , Thompson, Dori , Richey, Jon .
Late Cretaceous Plant Macrofloras From South-Central New Mexico: A Preliminary Report.
For two decades Late Cretaceous plant macrofossils have been known from south-central New Mexico. Intensive field and laboratory work over the past two years indicates the presence of abundant and diverse floras that range in age from middle Turonian to late Maastrichtian. This sequence of floras differs from most North American Cretaceous floral sequences in representing one small geographic region and environments that range from coastal plain to alluvial plain and piedmont.
The Carthage Member of the Tres Hermanos Formation is middle Turonian in age and represents coastal plain deposition. Permineralized/petrified wood of conifers and angiosperms is common. At least three types of angiosperm are present, including one species of Paraphyllanthoxylon. The Crevasse Canyon Formation is late Turonian to Campanian in age and documents the regression of the Western Interior Seaway in south-central New Mexico. The lower Coal-Bearing Member is late Turonian to Coniacian in age and represents coastal plain environments. Common leaf impressions and permineralized/petrified wood are known from crevasse splay, pond/lacustrine, and other sedimentary facies .At least one leaf macrofossil assemblage is 100-percent entire margined and has large leaf size, indicating warm, wet conditions. The overlying Ash Canyon Member is Campanian in age and represents alluvial plain environments at least 200 km from the paleo-coastline. Permineralized wood is common in the Ash Canyon Member, including logs of conifers and in situ stumps of the eudicot Metcalfeoxylon. The McRae Formation is Maastrichtian in age and represents alluvial plain to piedmont environments at least 200 km from the paleo-coastline. The lower Jose Creek Member is probably early to middle Maastrichtian in age and was deposited under warm humid conditions. Leaf macrofossils and permineralized wood are abundant and indicate a diverse flora of ferns, conifers,dicots, palms, and other monocots, many of which represent new taxa. The upper Hall Lake Member is late Maastrichtian in age and represents a change from humid to semi-arid conditions. Plant macrofossils are unknown from the Hall Lake Member, but pieces of mineralized coprolites yield a fragmentary flora of conifer shoots, dicot woods, angiosperm cuticle, and pollen.
The new fossil assemblages represent vegetation from the southern Western Interior near the northern shore of the Tethys Ocean. Study of these assemblages will provide important new data on flora during the rise of angiosperms, and climatic changes during the Late Cretaceous.
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1 - Texas State University, Department Of Biology, 601 University Drive, San Marcos, TX, 78666, USA
2 - New Mexico State University, Department of Geological Sciences, Las Cruces, NM, 88003, USA
3 - Texas State University, Department Of Biology, 601 University Drive, Del Carmen Coyoacan, San Marcos, N/A, 78666, Mexico
4 - DEPT OF WOOD & PAPER SCIENCE, 710 Dixie Trail, Raleigh, NC, 27607, USA
5 - 207 Pioneer Trail, San Marcos, TX, USA
6 - 1508 Mockingbird Dr, San Marcos, TX, 78666, USA
7 - 5608 Cougar Dr. #206, Austin, TX, 78745, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Wednesday, July 11th, 2012
Time: 9:15 AM