[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)

I'd like to insert two comments into this discussion:

Auguto Haro wrote:

<In my view, because *Microraptor* is not the outgroup of Avialae, nor does it 
represent the primitive character state for Deinonychosauria, so its 
"tetraptericity" might at best be its autapomorphy.>

  We do not actually know the basal state for Avialae, since the long feathers 
for *Microraptor* are confined to it as a genus (whatever that is). 
*Archaeopteryx* has tarsal feathers with a pinnate structure, although they are 
much shorter; it also appears that Archie may or may not have anything to do 
with the original avialaean condition, since it is technically a derived member 
(as is *Microraptor*). So neither of these taxa are terribly helpful in 
determining what is or is not the basal state -- either may be representative, 
or neither.

<As Cracraft (1971) indicated, femoral position is not always restricted to the 
parasagittal plane in birds, and thus there does not seem to be impedement for 

  Cracraft did not claim that the femur everted laterally as has been claimed 
in *Microraptor* (although revised by Xu et al., it's been seized upon by 
arguments _against_ theropod origin of birds by a very, very small minority). 
Make note, however, that it falls as a positive hypothesis to propose that 
femoral eversion and gliding are related; you will need to actually put forward 
evidence that you feel links femoral eversion to gliding behavior -- which to 
my knowledge has yet to be proposed (since all known legged gliders evert their 
femora is easily argued against, given that they arise in clades in which the 
taxa that surround them possess the same femoral eversion, even during normal 
terrestrial locomotion).


Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)