[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: [Re: Resting Sauropods]



> From: PTJN@aol.com
> archosaur@usa.net writes:
> << I mean if the above were true then we would have to call birds
cold-blooded
> sprawlers>>
> 
> Gee whiz.  Doesn''t anyone read these posts from start to finish?  This
is a
> totally nonsensical interpretation of my comments.  Please notice that I
> referenced '"tetrapod" reptiles.  What's the latest 4 footed bird you've
seen?

Turning to the _Encyclopedia of Dinosaurs_ glossary, we see that "tetrapod"
refers to either "(1), an animal having four legs or limbs;" or "(2),
amphibians and amniotes."  The same book states that the amniotes "include
modern reptiles, birds, and mammals."  But of course, from the cladistic
perspective, "reptiles" (or Reptilia) are not permitted to be a
paraphyletic (incomplete) taxon, that is, a group of animals which share a
common ancestor, but which does not include ALL animals descended from that
common ancestor.  Hence, the "reptiles" in the cladistic sense would
include many extinct and extant forms commonly referred to as "reptiles,"
but the birds as well, as they share a common ancestor with these forms,
too, and definitely belong within the same phylogenetic taxon, "Reptilia."

So, as you can see, the colloquial (dictionary) meanings of "tetrapod" and
"reptile" differ markedly from the cladistic meanings.  And it is proper to
refer to a bird as a "reptile" and a "tetrapod," whether you feel
comfortable with such labels or not.  I take it that you did not intend for
us to apply the cladistic definitions to your words. 

Sorry about that,

-- Ralph Miller III     gbabcock@best.com