Abstract Detail

Paleobotanical Section

DeVore, Melanie L. [1], Pigg, Kathleen B. [2].

Rethinking the tropical elements of the Eocene temperate forest: the Republic flora.

The Eocene flora of Republic, northeastern Washington has been a touchstone for forming our views on the early evolution of modern temperate groups such as Betulaceae, Acer and Rosaceae. This locality also bears fossils representing families with primarily tropical distributions, making Republic an important flora for understanding the Eocene constriction of widespread, Paleogene floral elements. Primarily tropical families reported from Republic include Bignoniaceae, Icacinaceae, Melastomataceae, Musaceae and Theaceae, as well as fossil cycads. While these occurrences have been discussed widely, most of the fossils upon which they are based have neither been studied in detail nor formally described. In our current work on the Republic flora we are carefully examining these reported occurrences to verify their identities and better understand where they fit within this complex floral assemblage. In some cases, we find that the assignment to tropical families needs to be reassessed. For example, specimens identified previously as the fruits of Ensete (Musaceae) are interpreted by us to be fragmentary receptacles of Nelumbo (Nelumboaceae) containing embedded fruits. In another case, fossil leaves previously assigned to Gordonia (Theaceae) have been found in attachment to stems bearing fruits comparable to Trochodendraceae. In still other cases, families with their greatest distribution in the tropics today, such as Bignoniaceae and Melastomataceae are known also to have living relatives in temperate zones. It is quite possible that this may have been the case in the past as well. We suggest that careful evaluation is needed before conclusively using these fossils to discuss biogeographical histories. Factors such as taphonomy, the size of the region providing the influx of plant material and the possibility for microhabitat bias should be taken into consideration

Broader Impacts:

1 - Georgia College & State University, Biological & Environmental Sciences, 135 Herty Hall, Campus Box 81, Milledgeville, Georgia, 31061, USA
2 - Arizona State University, School of Life Sciences, P.O. Box 874501, Tempe, Arizona, 85287-4501, USA

Keywords:
Republic flora
Eocene
tropical
Icacinaceae
Nelumboaceae
Melastomataceae
Theaceae
Musaceae
cycad
Bignoniaceae.

Presentation Type: Oral Paper:Papers for Sections
Session: 54
Location: 556A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 10:45 AM
Number: 54002
Abstract ID:681