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Re: Protoavis



Patrick Norton wrote:

<why would a theropod have such an advanced flight related structure>

and Larry Febo wrote:

<<I believe there are Coelurosaurs outside of Avialae that possess an
acrocoracoid tuberosity, so I'm not sure it is necessarily a flight
related feature.>>

  In the concepts of BCF and 2ndF'lessness, such a feature would be
tell-tale signs of a common, early origin of flight. Or in BAMMness,
it would be a sign of a development for something that was exapted
into a flight structure. Doesn't mean "flight"; pterosaurs and bats
lack such a feature and fly pretty darn well, as I'm sure Matt and
other bird-types will say.

and Pat Norton replied:
<Just to follow up (I just found the article I was thinking about)
Gauthier (1986) found a pronounced coracoid tuberosity among the
Deinonychosauria as well as Avialae.>

  It argues a well-supported clade between troodontids and
bird-related theropods, because oviraptors also have an acrocoracoid
process/tuberosity, and their scapulocoracoids are virtually identical
to dromaeosaurids. It seems to support a clade where troodontids are
the closest outgroup to the Oviraptorosauria + (Dromaeosauridae +
Avialae) clade. Wait 'til we find furculae in troodontids. Given
Mongolia's excellent preservation, that shouldn't be long if they're
there, but troodontids have always been fragmentary finds, and no,
*Saurornithoides* does not preserve a furcula: what's there are two
"clavicle"-like fragments on each side of the pectoral girdle, as in
*Segisaurus*, and may represent an ill-ossified furcula.

  Have fun,

==
- Often, it is the man who is brought
  down the path to the end who does
  not see his own steps. -

Jaime A. Headden

Qilong, the website, at:
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