UC Davis UC Davis Previously Published Works Title Angiosperm clades in the potomac group: What have we learned since 1977? Permalink https://escholarship.org/uc/item/5z89c18z Journal Bulletin of the Peabody Museum of Natural History, 55(2-3) ISSN 0079-032X Authors Doyle, JA Upchurch, GR Publication Date 2014-10-01 DOI 10.3374/014.055.0203 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Angiosperm Clades in the Potomac Group: What Have We Learned since 1977? James A. Doyle1 and Garland R. Upchurch, Jr.2 1 Corresponding author: Department of Evolution and Ecology, University of California, Davis CA 95616 USA —email:
[email protected] 2 Department of Biology, Texas State University, San Marcos TX 78666 USA —email:
[email protected] ABSTRACT In their 1977 study on Potomac Group angiosperms, Hickey and Doyle made only broad com- parisons with living taxa. Newer data, especially discoveries of fossil flowers in the Potomac and coeval deposits and increasingly robust molecular phylogenies of living angiosperms, allow more precise phylogenetic placement of fossils. Hickey and Doyle compared most early Potomac leaves (Aptian–early Albian) with “magnoliids,” a paraphyletic group as then defined, but several clades can now be recognized. Leaves and dispersed cuticles share epidermal features with woody mem- bers of the basal ANITA grade, and in some cases crown group Austrobaileyales, whose presence is confirmed by flowers called Anacostia. Aptian–Albian flowers (Monetianthus, Carpestella) and whole plants (Pluricarpellatia) are nested in crown group Nymphaeales; Potomac reniform leaves could belong to this clade. Several Potomac leaves have chloranthoid teeth, venation, and oppo- site phyllotaxis consistent with Chloranthaceae, while Aptian to Cenomanian flowers reveal the presence of both crown group Chloranthaceae (Asteropollis plant, near Hedyosmum) and stem relatives of this family and/or Ceratophyllum (Canrightia, Zlatkocarpus, Pennipollis plant, possi- bly Appomattoxia).