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Re: Turtles and Crocodylians are not Reptiles - no? What are they?



On Mon, Jul 21, 2008 at 7:54 PM, Erik Boehm <erikboehm07@yahoo.com> wrote:
> On the subject of differentiating reptiles from mammals, but including birds 
> with reptiles, I have to ask about one distinction between birds and mammals 
> not touched upon yet.
>
> WZ vs XY sex chromosomes.
>
> Do all the extant members of the traditional reptile group have WZ sex 
> chromosomes, where the heterozygote(WZ) is female, and the homozygote(ZZ) is 
> male, in contrast to mammals (XY=male, XX= female).

Well, in turtles as well as in crocodilians, we have temperature
dependent sex determination. Crocs are the extant closest relatives of
birds - and probably turtles are the extant closest relatives of
archosarus (birds + crocs).

[]s,

Roberto Takata