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Re: Egg-types and Taxonomy?



>I've been looking through "Dinosaur Eggs and Babies," and hev come across
>Figure 10.2.  This shows the basic types of dinosaur eggs and what groups
>that they've been atributed to.  There are basically three types of Dinosaur
>eggs: Dinosauroid-spherulitic, Dinosauroid- prismatic, and Ornithoid.  The
>D.-S. eggs have been atributed to Sauropods and Ornithischians, the D.-P.
>eggs to some ornithopods and marginocephalans, and the ornithoid eggs to
>theropods and birds (duh).  Anyways... I was thinking, if saurischia really
>was monophyletic, shouldn't sauropod eggs be in a group be themselves,
>different from the theropods' and ornithischians' eggs?  But on the other
>hand... if phytodinosauria was monophyletic shouldn't sauropod and
>ornithischians be more similar to eachother than they are to theropod's
>(which they are)?

If the D.S. egg was the primitive dinosaur condition, the ornithoid a
derived theropod condition, and the D.P. a derived cerapod (ornithopod +
marginocephalian) condition, you would get the patter seen above.  After
all, for every character, there is a primitive state.  Anyone know what is the
condition in dinosaur outgroups?

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