Mindell, Randal , Stockey, Ruth A. , Beard, Graham .
Anatomically preserved Castanopsis from the Eocene of Western North America.
Over 70 specimens of anatomically preserved pedicellate, cupulate fruits with seeds have been recovered and studied from the Eocene Appian Way locality on the eastern coast of Vancouver Island, Canada. Internal anatomy was studied using the cellulose-acetate peel technique. Three-dimensional reconstructions of external morphologies of both cupule and nut were generated using Amira 3.1 visualization software. The cupule surrounding these fruits is ornamented with vascularized elongate, forking spines that are also present along the pedicel. Vascular tissue runs along the inner wall of the cupule and branches out into the spines. The single maturing ovary is adnate to the cupule. No clear dehiscence lines have been observed, but the ellipsoid nuts (5-9 mm) are often found in isolation. Outer pericarp tissue is made up of sclerotic, small-diameter cells, while tissue of the inner pericarp is made up of isodiametric, thin-walled parenchyma. A longitudinal partition divides the ovary into two locules, with each half bearing one ovule. A central mass of seed tissue has been observed in mature fruits, suggesting that only one ovule matures. Given this suite of characters, these fruits are most similar to those found in extant Castanopsis (Fagaceae), a genus now restricted to Asia. Fruits belonging to this genus have been described from the Eocene of North America, but the Appian Way specimens represent the most complete fossil record of fruits known in the genus. They are a clear indication that indehiscent spiny cupules, spiny pedicels, single-seeded nuts and a 2-carpelled gynoecium were present by the Eocene.
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1 - University of Alberta, Department of Biological Sciences, Biological Sciences Centre, Cw 405, Edmonton, Alberta, T6G 2E9, Canada
2 - Vancouver Island Paleontological Museum, 151 West Sunningdale, Qualicum Beach, British Columbia, V9K 1K7, Canada
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 2:15 PM