Abstract Detail

Systematics Section / ASPT

Rothwell, Gar W. [1], Mapes, Gene [1].

Cladistic relationships of ancient voltzialeans: a paleontological perspective on the initial radiation of conifers.

Until the last few years, fossil voltzialean conifers from Late Paleozoic and Triassic deposits were thought to have been adequately characterized by the mid 20th century work of Florin and others. However, discoveries of new fossil materials and development of new methodologies for reconstructing extinct species of conifer plants have sparked renewed interest and an increased appreciation for the role that voltzialeans may have played in the radiation(s) of modern conifer families. These factors have also led to the proposal of several divergent hypotheses about the systematic relationships among the most ancient fossil conifers and living conifers. To begin to more fully understand the pattern of phylogeny of conifers and coniferophytes, we test competing hypotheses of relationships among walchian Voltziales, voltzialean Voltziales, Cordaitales, and other Paleozoic coniferophytes. Included in the analysis are two cordaitaleans, one vojnovskyalean, Dicranophyllum hallei, two Gondwana species, three Angara species, eight walchian species and five Late Permian and Triassic voltzialean species. The tree is rooted through the seed fern Callistophyton poroxyloides. Results of the analysis resolve ancient fossil conifers as monophyletic, and generally confirm Florin’s initial recognition that lebacheoid walchians are distinct from Ernestiodendron filiciforme. Questions that remain to be addressed are 1) whether extinct + extant conifers are monophyletic or if they represent parallel evolution(s) of the coniferophyte syndrome of characters, 2) what are the sister group relationships of conifers s.l., and 3) what are the sister group relationships of modern conifer families?

1 - Ohio University, Department of Environmental and Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA

Keywords:
Cladistics
Conifers
fossil
systematics.

Presentation Type: Paper
Session: 49-4
Location: Cottonwood C (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 11:30 AM
Abstract ID:531