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Re: Archosaur Origins...was:MESENOSAURUS ERRATA.
On Sat, 25 Aug 2001 Dinogeorge@aol.com wrote:
> With regard to integument, I was referring to that of possible >arboreal
> prolacertiforms<. If pterosaurs are prolacertiform descendants, then it is
> quite possible that some prolacertiforms already had the kind of hairlike
> "pelage" that is well known in pterosaurs.
IIRC, there are possible hairlike structures in _Cosesaurus_.
> This may, in turn, have also appeared other prolaceriforms, such as
> those from which those animals widely known as archosaurs evolved,
Are you using Prolacertiformes as a doubly paraphyletic group of
non-pterosaurian, non-archosauriform archosauromorphs?
Has it ever been defined as a clade? Clade(_Prolacerta_ <-- _Passer_,
_Crocodylus_) might work well, although then it could be synonymous with
> and it may have been preserved in the arboreal
> lineages that led to birds and dinosaurs. Secondary loss of hairlike
> "pelage," or conversion to smooth scutes, might be expected in aquatic
> reptiles such as proterosuchians, so absence of hairlike "pelage" in these
> groups does not preclude its existence in ancestral prolacertiforms.
Interesting, although that doesn't explain the lack of hairlike pelage in
terrestrial forms such as ceratopsids, hadrosaurids, titanosaurs, and
T. MICHAEL KEESEY
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