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RE: Paleogene Titanosaurs in South America? Paleogene ammonoids in the Persian Gulf? Not quite, but analogous...



> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of evelyn sobielski
> 
> Does anyone know the phylogenetic placement of 
> Corystospermales? I think "seed ferns" are nowadays assigned 
> to 4-5 different lineages, 1-2 of which is/are in the 
> gymnosperm-angiosperm clade. But very little seems known for 
> sure; insofar the new fossil may prove ultimately far more 
> important in a phylogenetic context than in a mass-extinction 
> context. 
> (Ibriefly looked up "seedfern" phylogeny some months ago for 
> a friend, and my impression was that there was a basic 
> agreement on their utter paraphyly, but very little consensus 
> on the actual relationships. They seem to be an 
> anatomical/life-history stage of higher land plant evolution, 
> still quite close to the base, that several lineages passed 
> through independently.)

The key reference in this context is

Hilton, J. And Bateman, R. M. 2006. Pteridosperms are the backbone of seed
plant evolution. Journal of the Torrey Botanical Society 133: 119-168.

Unfortunately I do not have a pdf of this journal (and would appreciate one
from someone with access :-), but I xeroxed part of it. I can't place my
hands on it right now, but the gist of the analysis was that "pteridosperms"
were a paraphyletic grade: they are all spermatophytes that aren't lucky
enough to be angiosperms, bennittataleans, gnetaleans [which might be
conifers...], conifers, cordaitaleans, cycads, or gingkos. So glossopterids
are stem-angiosperms, for instance, while (if I recall correctly)
medullosans were stem spermatophytes (i.e., outside of all living seed
plants). Cannot recall where Corystospermales fit.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Fax: 301-405-0796

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA