Re: Mesozoic-ware

[Jeff Poling <jpoling@infinet.com>]

At 05:33 PM 1/13/96 -0800, pharrinj@PLU.edu wrote:

>> >>    Dinosaurs certainly are reptiles.
>> >
>> >Which definition of "reptile" are you using?  If you mean "amniote minus 
>> >synapsid," I think "sauropsid" would be a better choice.  "Reptile" is 
>> >too connotationally loaded (cold-blooded, scaly, low-energy, egg-laying, 
>> >etc.).  Dinosaurs certainly were not "reptiles" in the vernacular sense 
>> >of the word.
>> 
>>    I use the clade version.  I'm not sure what the demarcation is ... I
>> suspect it isn't amniote minus synapsid as that would include amphibians ...
>
>Amphibians are tetrapods but not amniotes.  Amniotes are those tetrapods 
>that lay shelled eggs (or, for you more strict cladists, all descendants 
>of the last common ancestor of, say, me and a hoatzin).

   I'm still in the process of switching from Linneanism to cladistics.  As
I recally, amniotes are characterized by an egg with a fluid filled
(amniotic) sack.  Would this not, then, include amphibians?  I am assuming
that the choice of "amniota" in cladistics has a similar connotation, even
though it's based on descent rather than physical characteristics.

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