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RE: Monotremes



> -----Original Message-----
> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> Anthony Docimo
>
> > > > > if you say "monotreme"/"monotrema", I know you're talking about a
> > > > > mammal that lays eggs rather than having live birth.
> >
> >But not the other way around. The monotremes have _retained_ the condition
> >of laying eggs. We can be fairly sure that lots of Mesozoic mammals
> >(especially mammals in the wider senses) also laid eggs, "even though" they
> >were not monotremes.
>
> very well....so the next time a kid asks me "what's a word for egg-laying
> mammals?" (and yes, I have been asked this before)....what do I tell him?

If you are at a zoo, or are explicitly talking about modern mammals, then say 
"monotremes".

If you are talking about mammalian evolution, then no: monotremes are no more 
distinguished by laying eggs than humans are for
having five-fingered hands.

> do I say "synapsids"?

Different context. "Synapsids" should be used when you are talking about 
amniotes as a whole. If you are already dealing exclusively
with mammals, then you don't need this term. (Any more than one would use 
"amniotes" or "deuterostomes" or "bilaterians" when
talking about different mammal groups).

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796


>