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Abstract Detail


Paleobotanical Section

Mickle, James [1].

Fossil palm trunks from the Late Oligocene of Antigua.

The presence of silicified fossil wood has long been known on the eastern Caribbean Island of Antigua, but this material has remained largely unstudied. Recent collections of fossil wood on Antigua have shown, among other material, well-preserved silicified palm trunks. Antigua is roughly divided into three zones: the western volcanic zone, the central volcanic sediment zone and the eastern limestone zone. Silicified fossil wood specimens occur in the Central Plain Group of the central volcanic sediment zone, which is dated Late Oligocene. Specimens had eroded from sediments and were collected from the surface of the ground in fields (17° 04' 39.29" N 61° 48' 44.37" W) located near the Island Academy International School and were studied by thin section. All specimens recovered are stems. Collateral vascular bundles typically contain two prominent vessels; metaxlyem cells are few. The phloem fiber cap is reniform with the median sinus rounded and rounded auricular lobes. A single phloem strand is present. The f/v ratio is approximately 1.3-2.6/1. A thin fibrous ventral cap is present. Ground tissue parenchyma is thin-walled and compact. Numerous oval to rounded fiber bundle strands are scatted throughout the ground tissue. Stegmata were not observed. Epidermal and cortical features were not preserved. This fossil palm would be placed in Stenzel's group Reniforma. Direct comparisons with living palms is difficult due to incomplete information about both fossil and living palm characteristics. Despite this, the Antiguan fossil palm shows similarities in stem anatomy to subfamily Coryphoideae, tribe Sabaleae, which is native to the southeastern United States and eastern Caribbean islands. Members of Sabaleae and the Antiguan fossil show collateral bundles with two vessels, a single phloem strand and a large sheath in the bundle, as well as densely parenchymatous ground tissue containing scattered fiber bundles, inviting taxonomic comparison. However, lack of data on key comparative stem features and lack of stegmata preclude direct placement within Sabaleae. The Antiguan palm possesses a distinctive suite of features that suggest recognition as a new species within the genus Palmoxylon.

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1 - North Carolina State University, Department of Plant Biology, Campus Box 7612, 2115 Gardner Hall, Raleigh, NC, 27695-7612, USA

Keywords:
palm
Palmoxylon
Oligocene
Antigua
Sabaleae.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM
Number: PPB005
Abstract ID:287


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