Deep Time: Integrating Paleobotany and Phylogenetics
Doyle, James A. , Endress, Peter K. .
Integrating Early Cretaceous fossils into the phylogeny of Recent angiosperms.
Many Early Cretaceous angiosperm flowers and pollen types have been compared with living taxa, but few such comparisons have been tested with phylogenetic methods. We have used a morphological data set for living basal angiosperms (including basal eudicots and monocots) to assess the relative parsimony of placements of early angiosperm fossils on a Recent tree based on morphological and molecular data and investigate implications for character evolution. This analysis confirms proposed relationships of several fossil taxa. Flowers with Asteropollis pollen are linked with Hedyosmum (Chloranthaceae), Anacostia is nested in Austrobaileyales, and Archaeanthus is linked with Magnoliaceae. Among Albian eudicots, Sapindopsis, Nelumbites, and Spanomera appear related to Platanus, Nelumbo, and Buxaceae, respectively. Affinities of dispersed pollen types are less robust, but our data support relationships of Walkeripollis tetrads with Winteraceae and Liliacidites (monosulcates with finer sculpture at the ends of the grain) with monocots. However, other fossils seem less closely related to previously suggested relatives. Virginianthus may be sister to either Calycanthaceae or the remaining Laurales; either result implies that reticulate rather than psilate monosulcate pollen was ancestral for Laurales and eumagnoliids as a whole. Mauldinia may be sister to both Lauraceae and Hernandiaceae rather than Lauraceae alone. Couperites (with “Clavatipollenites” pollen) may be related to Chloranthaceae, but positions in the basal ANITA grade are equally parsimonious. Plants with coarsely reticulate Pennipollis pollen appear related to Chloranthaceae rather than monocots, while Appomattoxia (with pollen resembling Chloranthaceae but with a continuous tectum) is more parsimoniously placed near Chloranthaceae or Amborella than in Piperales. Our analysis does not address the possibility that Archaefructus is basal to all living angiosperms, but its most parsimonious position within angiosperms is with Hydatellaceae, recently linked with Nymphaeales, indicating an early trend toward floral reduction in an aquatic habitat.
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1 - University of California, Davis, Section of Evolution and Ecology, One Shields Ave., Davis, California, 95616, USA
2 - University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, 8008, Switzerland
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 4/Hilton
Date: Monday, July 9th, 2007
Time: 1:30 PM