Abstract Detail

Campanian-Maastrichtian floras on Laramidia: vegetation trends west of the seaway

Boucher, Lisa [1].

Reconstructing a Late Cretaceous woodland flora from southern Laramidia using fossil leaves and wood.

The Fruitland and Kirtland Formations (Late Cretaceous, 75.5-73 Ma) of northwestern New Mexico contain well-preserved leaf and reproductive macrofossils as well as silicified wood providing information about the plant diversity and ecology along a heterogeneous floodplain landscape. This study will summarize data from over twenty-five sites that have been extensively sampled for compression/impressions, and from well over sixty wood specimens collected from in situ stumps and logs in the same region. The leaf and wood data have been analyzed for paleoclimate variables, and they support subtropical-tropical temperatures with possible environmental disturbances and fluctuations in water availability. Leaf assemblages at some sites are dominated by angiosperms, whereas pteridophytes and conifers are more abundant at others with correlations to different subenvironments along the floodplain. Over 100 morphotypes have been identified including a leaf flora consisting of a variety of basal and eudicot angiosperms, palms, other monocots, araucariaceous and taxodiaceous conifers, and several fern orders including the Osmundales, Schizaeales and Polypodiales among others. Although much of the wood is coniferous (Cuppressinoxylon and Araucarioxylon), several angiosperm xylotypes have been identified such as Palmoxylon, Baasoxylon, and Paraphyllanthoxylon. Most of the larger stumps are conifers, with fewer angiosperms reaching larger tree sizes, and spacing is consistent with open canopy woodlands. Because sites are heterogeneous on small spatial scales, the fossil type, sample size, and depositional setting play key roles in making meaningful comparisons between floral assemblages at different sites locally and globally. However, these data when combined with other sedimentological, microfloral, and geochemical data will provide a clearer picture of the evolutionary and paleoecological trends seen in Late Cretaceous floras.

1 - University Of Texas At Austin, Department Of Biology, 110 Inner Campus Drive F0404, Austin, TX, 78712-1711, USA

Keywords:
Cretaceous
Campanian
paleoecology
fossil wood
leaf macrofossil
landscape heterogeneity
New Mexico
Laramidia
Fruitland Formation
Kirtland Formation.

Presentation Type: Colloquium Presentations
Session: CO3, Campanian-Maastrichtian floras on Laramidia: vegetation trends west of the seaway
Location: Sundance 3/Omni Hotel
Date: Wednesday, June 28th, 2017
Time: 10:15 AM
Number: CO3007
Abstract ID:521
Candidate for Awards:None