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Re: Archie skull pneumatics?



----- Original Message -----
From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com>

> David Marjanovic wrote-
>
> > (3) is wrong,
>
> Why?  Because Scansoriopteryx also has it?

Because both characters are suspiciously widespread. Depending on the
phylogeny, mononykines, *Microraptor* (almost -- it has a few serrations
left), *Byronosaurus* and/or *Incisivosaurus* might be relevant. Didn't know
about *S.* (that book hasn't arrived yet). Of course, "depending on the
phylogeny" is the crucial point.

> > (7) is wrong because of *Microraptor* [...]
>
> But Microraptor has more caudal vertebrae (24-26) than Archaeopteryx (22).

I thought 25 for *A.* and 24 or 25 for *M.*. Right, the new paper says 24 --
26 for *M.*. But only 22 for Archie? Haven't I counted more myself on
photos? ~:-|

> Sinornithosaurus may not (~20) though.

Wow.

> > but could someone give me a broader picture of where
> > these characters occur?

Thanks a lot!!! Cool distributions -- troodontids, alvarezsaurs and "more
obvious birds", oviraptorosaurs and birds except confuciusornithids...

> The condition in Protarchaeopteryx is unclear, though Witmer (2002)
supports
> a lack of serrations.

To be precise, the original authors say 7 -- 10 per mm, and he can't see
this even with his hand lens. One such serration would be the size of a
large *Paramecium* or amoeba, so I doubt the authors were able to see
this... or that Witmer can see them if they are present.
        But... really tiny serrations appear to exist. In the Guimarota book
(Fig. 12.3, p. 85) there is a SEM image of one of the "cf. *Archaeopteryx*"
teeth*. It has 5 serrations or rather crenelations on 1/4 mm, twice the
number for *Protarchaeopteryx*.

* "With an average height of 1.65 mm, the teeth from the Guimarota mine are
considerably larger than those of *Archaeopteryx* from [...] Solnhofen
[...]" (p. 84).

> (Barsbold et al.'s first caudal is fused to the sacrum, so I
> view it as a sacral)

A more common definition seems to be: sacral = vertebra that has sacral
ribs. (Which need, in mammals, not contact the pelvis.)