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Abstract Detail


Paleobotanical Section

Smith, Selena Y. [1], Little, Stefan A. [2], Burnham, Robyn [3], Stockey, Ruth A. [4].

A woody axis with liana anatomy from the Cretaceous of Hornby Island, British Columbia.

A variety of fossils have been preserved in calcareous concretions from Cretaceous (Campanian) sediments of Collishaw Point, Hornby Island, British Columbia, including marine birds, mosasaurs, sharks, oysters, clams, ammonites and anatomically preserved plants. Among these plants is an incomplete woody angiosperm stem discovered in a fractured nodule. This stem was sectioned and studied with the cellulose acetate peel technique. The stem segment is 2.5 cm in diameter and 2.8 cm long. The center of the axis and peripheral tissues are incompletely preserved and appear to have been abraded prior to preservation. In transverse sections, one growth increment is seen for the entire axis, and secondary xylem occurs as wedges separated by large rays more than 10 cells wide. Wood is diffuse porous and vessels are solitary or in multiples of two (rarely three or four). Vessels are large, with a mean diameter of 227 µm. In longitudinal sections, vessel elements are long with a mean length of 912 µm forming vessels up to at least 17.2 mm in length, and bear medium to large, crowded, elliptical to flat elliptical, alternate pits. Axial parenchyma has not been observed, however, vessels are surrounded by vasicentric tracheids with pitting similar to vessels. Rays are homocellular and >2 cm tall. Phloem rays are dilated, intrude into the xylem rays, and cells are thick-walled with possible prismatic crystals. Periderm is composed of lignified tissue with sclerotic nests and an outer zone of thin-walled cells. Long, wide vessels, vasicentric tracheids, and tall, wide rays are characteristics of extant liana stem anatomy. There are few known examples of liana wood from the Cretaceous, so this specimen provides additional information about early angiospermous lianas. Because lianas are characteristic of ecologically complex forests, the fossil axis suggests that the terrestrial ecosystem was probably diverse, complementing the marine faunal assemblage of Collishaw Point.

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1 - University of Michigan, Museum of Paleontology and Dept. of Geological Sciences, 1109 Geddes Avenue, Ann Arbor, MI, 48109, USA
2 - University of California Davis, Department of Plant Sciences, One Shields Avenue, Davis, California, 95616, USA
3 - University of Michigan, Ecology and Evolutionary Biology, Museum of Paleontology, 1109 Geddes Avenue, Ann Arbor, Michigan, 48109-1079, USA
4 - University of Alberta, Dept. of Biological Sciences, Edmonton, AB, T6G 2E9, Canada

Keywords:
Cretaceous
Fossil
Hornby Island
liana
wood.

Presentation Type: Oral Paper:Papers for Sections
Session: 32
Location: 555A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 10:45 AM
Number: 32003
Abstract ID:739


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