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Re: Tarsitano's challenges




<<(2) the lack of clear evidence of a fenestra rotundum in coelurosaurs;>>

<This may be present in oviraptorids andtherizinosauroids, or at least an homology to it (Elzanowsky, 1994, 1999?, in press; Barsbold, 1983; Maryanska and Osmolska, 1996)>

_Dromaeosaurus_ exhibits a fenestra pseudorotundum (Currie, 1995). Gauthier (1986) reports a fenestra pseudorotunda in _Tyrannosaurus_. Troodontids (Currie, 1985) apparently show one too.

Tarsitano (1985) identifies the archosaur fenestra pseudorotundum based on whether or not it is bordered caudally by the metiotic strut. However, he seems to reinterpret what a metiotic is when he is discussing theropod braincases.

<<(4) reduced coracoids in all coelurosaurs;>>

<Dromaeosaurs do not have reduced coracoids. Subjective definition of reduction supposes to Tarsitano that birds do not have elongated coracoids, thus supposing the relatively shorter ones in many theropods are altogether different evolutionarily. The coracoids of *Sinornithosaurus* (Xu, Tang, and Wang, 1999), *Velociraptor* (Norell and Makovicky, 1999) and *Bambiraptor* (Burnham et al., 2000) are very avian in having derived coracoid necks and even a possible acrocoracoid process and triosseal canal in the latter. *Unenlagia* and *Bambiraptor* have dorsally elevated glenoid facets, though maybe not as dorsally oriented as previously though (I'm refering to Paul's talk as SVP'99, looking forward to seeing the publication of his latest efforts and Norell and Makovicky's continued introspection of *Unenlagia*).>

Oviraptors and troodontids don't have reduced coracoids either. _Sinornithosaurus_ (Xu et al., 1999) is extremely birdlike in pectoral structure; the scapula is straplike, the scapula and coracoid meet at a right angle, there is a pronounced acrocoracoid process, and the coracoid locks into the sternum. Compare this to _Archaeopteryx_.

<<(6) the presence of the middle temporal arch in coelurosaurs, but its absence in birds;>>

<Confuciusornithids have complete and quite robust
postorbital/jugal, ~/squamosal, jugal/quadratojugal,
quadratojugal/squamosal contacts, *Archaeopteryx* has
been variously interpreted as having complete but
broken or absent a few temporal bones. Matt Troutman
can answer this question better than I can.>

Whetstone (1983) interpreted _Archaeopteryx_ as missing a squamosal or at least not incorporating into the quadrate articulation (the quadrate, in his version, articulated directly into the braincase on the opisthotic). Walker (1985) disputed this, and Elzanowski and Wellnhofer (1996) described the _Archaeopteryx_ squamosal complete with an articulation for the postorbital. What is not known is how far the postorbital extends down, and whether it contacts with the jugal, which seems to lie on the side of the quadratojugal and quadrate.

Matt Troutman
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