Re: Archie skull pneumatics?

["Nick Gardner" <ratites637@hotmail.com>]

David Marjanovic wrote-
> But why I'm writing this to the list is that I don't know about (5) and 
> (6). I expect Witmer (who else?) knows what he's writing about here (he 
> also cites
> himself for both), but could someone give me a broader picture of where 
> these characters occur?

Though, I imagine myself as the least likely to have ever responded, I find 
myself doing so regardless.  Reminds me of "The Fellowship of the Ring", 
which I saw for the first time last night.

Do you mean to say that the reflexed hallux was absent in Archaeopteryx, or 
that the character is plesiomorphic for it, perhaps instead synapomorphic 
for Eumaniraptora, in light of *Microraptor* and *Scansoriopteryx*?

The elongated prenarial premaxilla is present in "enigmosaurs" (as David 
noted), spinosaurids (Sereno et al. 1998; Sues et al. 2002), and avians.  I 
never really understood this character but I assume it could be related to 
dietary functions? Help... please.

I was under the impression that *A.* did not have an incomplete postorbital 
bar.  I know that *Shuvuuia* does not (Suzuki et al. 2002), and that the 
contact between the postorbital and jugal is weak in *Bambiraptor* (Burnham 
et al. 2000).

How many non-avian theropods lack dental serrations anyway?  I can only 
think of *Caudipteryx*, *Byronosaurus*, *Compsognathus*, and juvenile 
tyrannosaurids.  I'm sure there must be more, but I can't think of them all. 
 I thought that perhaps *Scansoriopteryx*, *Microraptor*, coelophysids, 
*Dilophosaurus*, and *Shuvuuia* might, but I can't be sure.

As for basal constriction of the teeth in non-avian theropods, I know it is 
present in *Caudipteryx*, *Microraptor*, *Shuvuuia*, segnosaurs, 
troodontids, and perhaps *Protarchaeopteryx*?

Perhaps he meant the enlargement of the cranial cavity relative to body 
size?

According to Xu et al. (2002), the caudal tympanic recess opens into the 
columellar recess in *Archaeopteryx*, *Sinovenator*, and *Shuvuuia*.  
Chiappe (2001) codes it as present in *Archaeopteryx*, *Mononykus*, 
*Shuvuuia*, *Hesperornis*, *Anas*, & troodontids.  All the other avians in 
his analysis are coded as "?".

I cannot say anything much regarding the caudal maxillary sinus, because I 
am not familiar with it.

I agree that the distal reduction of the caudal prezygapophyses does seem 
suspect, especially when you take *Jeholornis* into account.  However, I was 
not aware that *Microraptor* had a caudal count comparable to 
*Archaeopteryx* or other avians.  There are other non-pygostylian theropods 
with very short tails, such as the avian *Jeholornis* (22), the curious 
*Protarchaeopteryx* (23), and *Caudipteryx* (22).

I wish the last character was not so vague...


Nick Gardner

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