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Re: birds and avians again



On Fri, 31 Aug 2001, Jaime A. Headden wrote:

>   I beleive both Chelonia and Crocodylia use fossil
> specifiers/anchors, but I cannot recall them off the top of my head.

No, I think they are crown groups. And actually, since _Chelonia_ is also
a genus, I think _Testudinata_ or _Testudines_ would be a preferable name
for the larger clade.

> Tetrapoda as well.

This was once defined as a crown group, but I think that proved unpopular
(much like for _Aves_). I'm not sure what the preferred definition is, but
it might be something like Clade(_Elginerpeton_ + _Homo_) or Clade(_Homo_
<-- _Panderichthys_, _Elpistostega_).

> Amniota is a stem excluding lissamphibians,

I think it's a crown group, _Amniotomorpha_ being the stem.

> and Synapsida is a stem from Sauropsida, or conventionally, Reptilia.
> Reptilia is a crown group clade comprising Chelonia, Lepidosauria
> [incl. snakes and mosasaurs], Crocodylia, and Dinosauria [incl.
> birds]. That these groups are already viable and the vernacular
> applies to them easily,

I would disagree in the case of _Reptilia_, a name that I really wish had
been dropped.

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