Re: Did non-avian dinosaurs guard nests?

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 01:18 PM 10/21/97 -0400, John Bois wrote:

>3. All (except for one)  avian species tend nests.  And most crocodilians
>tend nests.  Can I say anything here about extant phylogenetic bracketing.
>Or can I use this statement as any kind of support?

This is a great case for the extant phylogenetic bracket.  A behavior is
shared by both extant brackets (forms with very different ecologies and body
plans) and is rare among outgroups.  There is a strong case that nest
attendance is a behavioral synapomorphy of Archosauria, and suggestion that
a particular extant or extinct archosaur did not practice said behavior
would require additional evidence.

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