Symposia: Emerging Results from Studies of Gymnosperms on the Tree of Life II
Seyfullah, Leyla J. , Hilton, Jason .
The position of pteridosperms as the backbone to seed plant evolution.
When fossils are included in morphological cladistic analysis of seed plant relationships the now 'traditional' anthophyte hypothesis of relationships is produced in which Caytonia, Bennettitales and Gnetales, in various positions, are sister to angiosperms. This long-prevailing hypothesis has been disputed by various molecular analyses that exclude fossil taxa and place Gnetales in a variety of positions from sister to all other seed plants, to sister to conifers, or within conifers. This talk will explore morphological analyses of seed plant relationships using extinct and extant taxa and will present a new analysis based on new taxon selection, new character codings, and integration of previously published matrices. Five important points will be considered, namely (1) the effect of outgroup selection and the benefits of matrix expansion to include progymnosperms, (2) taxon selection within pteridosperms and over or under-representation of known groups, (3) the top-down effect exerted by angiosperms and taxon selection within this group, (4) taxon selection and relationships within conifers, (5) the effect of paedeomorphism resulting in more derived positions of key taxa.
Log in to add this item to your schedule
1 - University of Birmingham, Earth Sciences, School of Geography, Earth and Environmental Science, Edgbaston, Birmingham, B15 2TT, U.K.
Presentation Type: Symposium or Colloquium Presentation
Location: Ballroom C/Convention Center
Date: Monday, August 2nd, 2010
Time: 9:00 AM