Abstract Detail

Themes of land plant evolution, a celebration of the contributions of Leo J. Hickey

Stromberg, Caroline [1], HilleRisLambers, Janneke [2], Wing, Scott [3].

Neo-ecology in deep time: Reconstructing plant paleo niches in the Late Cretaceous of Wyoming.

It has commonly been assumed that, prior to their rise to ecological dominance in ecosystems, flowering plants differed from other plant groups in their ecology. For example, based mainly on phylogenetic comparative analyses, functional morphology, and broad facies associations, it has been suggested that these 'early' angiosperms preferentially occupied disturbed habitats. However, the fine scale information needed to determine whether angiosperms occupied fundamentally different niches than coexisting taxa is not typically preserved in the fossil record. The Late Cretaceous (~73 Ma) Big Cedar Ridge (BCR), Wyoming, constitutes an exception. Preserved at the base of an ashfall, this unique flora records the spatial location of individual plants in a landscape where dicots were still very rare. The dataset consists of 122 taxa censused at 100 sites along almost four kilometers of outcrop, and quantitative measurements of four environmental characteristics (e.g., paleo-elevation, paleosol Total Organic Content (TOC)) at each site. We applied statistical methods used in modern ecology to quantify the environmental niches of co-occurring 'dicots', ferns, monocots, conifers and cycads, focusing specifically on differences in abundance, niche optima and niche breadth relative to flooding and/or pH (as indicated by TOC). Analyses showed that dicots were generally less abundant than co-occurring monocots, conifers, cycads and ferns. Also, dicots typically occupied lower TOC values than other functional groups. Finally, dicots tended to have narrower environmental niches than co-occurring taxa. In all, this indicates that most dicots in this Late Cretaceous ecosystem either had narrow physiological tolerances or were competitively inferior to co-occurring plant groups. Importantly, dicots varied greatly in abundance, niche optimum and niche breadth. This pattern indicates that, at a time when dicots were still ecologically marginal, they were both diverse and distinct in ecological strategy.

Broader Impacts:

Related Links:
Stromberg lab website

1 - University of Washington, Biology & Burke Museum, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195-1800, USA
2 - University of Washington, Biology, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195-1800, USA
3 - Smithsonian Institution, Dept. of Paleobiology NHB 121, PO Box 37012, WASHINGTON, DC, 20013-7012, USA

Keywords:
Paleobotany
paleoecology
Angiosperms
ecological niche
Cretaceous.

Presentation Type: Symposium or Colloquium Presentation
Session: C6
Location: Belle-Chasse/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 2:30 PM
Number: C6004
Abstract ID:652
Candidate for Awards:None