Abstract Detail

Fossil plants at the intersection of evo-devo and phylogeny: celebrating the contributions of Gar W. Rothwell to biodiversity and evolution

Stevenson, Dennis [1].

Cycads Past and Present.

The Cycadales have a good fossil record beginning in the early Permian with over 20 known fossil genera and 10 extant genera.  There are at least ten autapomorphies defining all extant taxa.  There are at least a dozen autapmorphies that occur with the extant cycads.  All in all, there are 20 of these anatomical such as girdling leaf traces, omega pattern of vascular bundles in petioles, cone domes, etc.  This allows for the identification of fossils as cycads and analyses that include those fossils.  Although the fossils are not known as whole plants, these characters do allow the leaves and stems to be resolved on stem lineages of the extants within the order.  This in turn can be used to generate hypotheses concerning whole plant reconstructions and gives us minimum ages for the clades.  The fact that these structures have persisted through the Triassic and Jurassic to today leads to questions and hypotheses concerning the function and conservation of the autapomorphies.  For example, the cone domes are probably the result the dichotomous branching coupled with cone formation and maturation at the apex

1 - New York Botanical Garden, Science, 2900 Southern Boulevard, Bronx, NY, 10458, USA


Presentation Type: Colloquium Presentations
Abstract ID:253
Candidate for Awards:None

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