Hudson, Patrick J. , Boucher, Lisa .
Taxonomy and paleoclimate analysis of Late Cretaceous wood from New Mexico.
THE Fruitland-Kirtland Formation of northwestern New Mexico contains abundant and well-preserved macrofloras from a Late Cretaceous (Campanian-Maastrichtian) floodplain. These macrofloras preserve a valuable record of woody angiosperms radiating into floodplain subenvironments previously dominated by conifers. This project examines permineralized wood from these sites with two objectives: to classify the taxa with secondary growth, and to use their anatomical characters as paleoclimate indicators. A total of fifty specimens comprising twelve dicots, five monocots and thirty-three conifers were analyzed using cellulose-acetate peel technique in conjunction with light microscopy and scanning electron microscopy. The twelve dicot remains yielded four morphotypes, with possible affinities to the Laurales and several orders within the Eurosids I. The anatomical characters of the five monocot specimens indicated that they belong to the form genus Palmoxylon. The majority of conifer specimens have anatomical characters designating them as the Cupressinoxylon/Taxodioxylon-type; the others are of the Araucarioxylon-type. Values generated from mean sensitivity analysis of the growth rings and interruptions in the conifer wood ranged from 0.34 to 0.58, indicating that these plants inhabited a seasonally stressful environment. Based on the presence of Palmoxylon and other data relating climate to leaves and wood anatomy, the growth rings and interruptions were most likely due to fluctuations in precipitation rather than temperature.
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1 - University of Nebraska Omaha, Department of Biology, 114 Allwine Hall, Omaha, Nebraska, 68182-0040, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 2:30 PM