Re: Paedomorphosis ( Re: BARYONYX' CLAWS )

["Matthew Troutman" <m_troutman@hotmail.com>]

>>1) Acute scapulacoracoid angle. 
>>2) Posteriorly facing coracoid with a peg-like or weakly strut-like 
>>shape.
>>3) Single sternum.

<<Pretty sure _Archaeopteryx_ lacks two out of three of these (1 and 
2--I'm going by Larry Martin's 1991 description here, in which he 
comments on _Archaeopteryx_ as having a "coracoid that does not differ 
greatly from that of other theropods"), while many flightless theropods 
did have (3).>>

     Wellnhofer, in his reconstruction of the scapulacoracoid of 
Archaeopteryx bavarica, showed the coracoid is more rounded and 
strut-like than most authors reconstruct. Plus, the scapulacoracoid 
angle was also shown to be acute ( this is backed up by my observation 
of the specimen ). Norell et Makovivky also state that in theropods 
there are no instances of a complete single sternum.

<< _Archaeopteryx_ certainly was able to fly--though not like modern 
birds fly--so your thesis that flight is impossible without these 
features needs to be reexamined (to say the least). Do not limit 
yourself to describing as "flight" specifically the kind of flight that 
modern avians have; try to imagine what kind of flying dinosaurs such as 
_Archaeopteryx_ and earlier, as yet unknown forms might have been 
capable of.>>

     How can an animal fly without some of the flight characteristics 
seen in birds? Flight muscles exert strong compressive forces (and need 
to ) and these forces need to be supressed. I just keep on thinking 
about the statement that if Daudalus were to be able to fly with his 
wings his torso would have to be six foot thick with muscle and his 
complete wingspan would have to be 140 feet! The only type of flight 
that I can imagine is flapping flight, however primitive it may be.

<<You are rapidly approaching the "flight is a miracle" school of 
current dinosaurology. Of course theropods lacked the well-developed 
flight apparatus of modern birds. It hadn't yet evolved when the typical 
theropod groups began to diverge from the lineage that led to modern 
birds.>>

     I still do not see how the typical theropodian shoulder can make an 
animal capable of flight. Even Archaeopteryx has a pretty sophisticated 
shoulder. Flight can only be possible if the features needed for flight 
evolved for something else and then were exapted for flight ( just like 
how limbs evolved ).

MattTroutman

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