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RE: New gliding reptile: Mecistotrachelos
Paula Goodman wrote:
*how do the wings of this new fossil relate to the
maybe-feathers/maybe-scales wings of the Longisquama?
In their description of _Mecistotrachelos_ Fraser &c leave open the question
of where exactly _Mecistotrachelos_ might lie in diapsid phylogeny, though
they tentatively suggest it is an archosauromorph (i.e., closer to birds and
crocodiles than to lizards and snakes). It might even be closely related to
The kuehneosaurs, another group of extinct gliding diapids, are usually
regarded as lepidosauromorphs (i.e., closer to lizards and snakes than to
birds or crocodiles).
_Longisquama_ isn't mentioned in the description, but an analysis of
_Longisquama_ a few years back (Senter, 2004) recovered _Longisquama_ in a
group he called the Avicephala, which also includes drepanosaurids and
coelurosauravids. This group lies somewhere near the base of the Diapsida,
outside both the archosauromorphs and lepidosauromorphs.
So to answer your question, at the moment there does not appear to be any
unique connection between _Mecistotrachelos_ and _Longisquama_. Gliding
abilities appear to have evolved several times independently among small
diapids. Having said that, the precise function and arrangement of the
dorsal structures of _Longisquama_ is not known; it could be a single file,
or a paired structure like _Coelurosauravus_ or _Mecistotrachelos_ or
Nor does there appear to be any connection at all between _Longisquama_ and
birds; the dorsal structures present in _Longisquama_ (which *might* have
been used for gliding) do not appear to be homologous to bird/theropod
feathers. _Longisquama_ is only distantly related to birds; if Senter's
analysis is correct, _Longisquama_ is no more closely related to birds than
to lizards or snakes.
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