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Re: Another mosquito query



At 09:32 PM 4/19/97 EDT, Judy Molnar wrote:

>This would only work if dinosaurs had nucleated red blood cells, too. 
>Birds and reptiles do, mammals don't.  Does anyone know if dinosaurs did?

By the Extant Phylogenetic Bracket method, nonavian dinosaurs almost
certainly had nucleated erythrocytes, as extant dinosaurs (birds) and all
the closest living outgroups to Dinosauria (Crocs, Lepiodsaurs, Turtles) and
more distant outgroups (Lissamphbians, some (most? all?) "fish") do.

The lack of nuclei in red blood cells is a mammalian autapomorphy (a derived
character unique to this group, at least among the amniotes, and possibly
among all vertebrates (as noted above, I don't know the condition in the
various non-tetrapod vert groups).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661