Estrada-Ruiz, Emilio , Upchurch, Garland , Wheeler, Elisabeth , Greg, Mack H. .
Late Cretaceous dicotyledonous woods from the Crevasse Canyon and McRae Formations, south-central New Mexico, USA: Part I.
Late Cretaceous angiosperm woods from the Western Interior, U.S.A., are poorly known relative to palynomorphs and leaf macrofossils. Recently, abundant and diverse angiosperm woods have been reported from the Campanian to Maastrichtian of Coahuila, Mexico, and Big Bend National Park, Texas, but less is known about angiosperm wood diversity in coeval deposits to the north. The Campanian Crevasse Canyon Formation and Maastrichtian McRae Formation of south-central New Mexico, U.S.A., provide an abundant record of silicified woods that expands our knowledge of dicot wood diversity during the Late Cretaceous. The Crevasse Canyon Formation yields woods belonging to Metcalfeoxylon (Malvales) and Paraphyllanthoxylon (probably Lauraceae), two genera previously described from the Western Interior Cretaceous. The Jose Creek Member of the McRae Formation yields the genus Plataninium (Platanaceae) and woods that appear to represent new genera. These latter woods include one species ofCelastraceae, two types of probable Myrtales, and a eudicot of uncertain affinity. A range of plant sizes and life forms is indicated by the woods. Metcalfeoxylonis known from in situ stumps with maximum basal diameters up to 0.75m respectively, and woods of Paraphyllanthoxylon known from other areas come from trunks up to 1 m in diameter. The woods of Celastraceae and possible Myrtales have axis sizes consistent with their derivation from small trees,large shrubs, and/or vines, while the eudicot of uncertain affinity has a small diameter axis and wood anatomy consistent with its derivation from a small plant(low density of small vessels and large quantities of parenchyma). Our work indicates that certain taxa, such as Paraphyllanthoxylon and Metcalfeoxylon,were important angiosperm trees from paratropical regions of North America, and that others may have been more endemic in their distribution and/or plants of smaller stature.
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1 - Texas State University, Department of Biology, 601 University Drive, San Marcos, TX , 78666, U.S.A.
2 - North Carolina State University, Department of Wood and Paper Science, Raleigh, NC, 27695, U.S.A.
3 - New Mexico State University, Department of Geological Sciences, Las Cruces, NM, 88003 , U.S.A.
Crevasse Canyon Formation
Presentation Type: Oral Paper:Papers for Sections
Location: Forsyth Room/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 9:15 AM