Abstract Detail

Paleobotanical Section

Herendeen, Patrick S. [2], Manchester, Steven R. [1].

Fruits and foliage of Cercis from the Late Eocene of Oregon.

The fossil history of Cercideae is of particular interest because this tribe is monophyletic and sister to all other legumes. However, Cercideae are poorly represented in the fossil record as compared to many other groups of woody legumes. As a step in tracing the fossil record of this group, we introduce a new Eocene record for the genus Cercis. The fruits and leaves are preserved as impressions in shale of a late Eocene (ca 36-38 ma) pond deposit known as the Teater Road site in the John Day Formation of eastern Oregon. The legume fruits and leaves exhibit several morphological characters that, in combination, are only found in the genus Cercis. The fruits are membranous with a narrow non-vascularized wing along the placental suture. The leaves are unifoliolate and possess two pulvini--one at the junction of the petiolule with the base of the cordate lamina and the other at the base of the petiolule. This fossil taxon represents the oldest verified representative of the genus Cercis. These fossils occur in a diverse warm temperate assemblage that also includes Salvinia, Acer, Ailanthus, Alnus, Craigia, Dipteronia, Engelhardieae, Eucommia, Koelreuteria, Hydrangia, Mahonia, Paliurus Quercus, Ulmus and the extinct genera Cedrelospermum, Chaneya, and Florissantia. Cercis is the only temperate member of the tribe Cercideae; the other genera are tropical and subtropical. Because several other lineages of legumes are known already from the late Paleocene, we conclude that the Cercideae must have been present, but its early fossil record remains undiscovered or unrecognized.

1 - University of Florida, Department of Natural History, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
2 - George Washington University, Biological Sciences, 2023 G St.NW, Washington, DC, 20052, USA

Keywords:
Eocene
foliage
fossil
Fabaceae
fruits
Oregon.

Presentation Type: Paper
Session: 5-13
Location: Maybird (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 11:45 AM
Abstract ID:624