RE: Peculiar Femoral Feathers

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Waylon Rowley wrote:

> When you imagine the hindlimb folding
> up into the position seen in birds during flight, it
> becomes apparent that the thigh feathers overlap the
> shin and foot, smoothing this area out. Basically,
> just covering the "landing gear". Might have made a
> big difference aerodynamically in a flapping dino. 

As Jim said, a very interesting idea.  However, in the initial/incipient
stages, these aerial forays would have been extremely brief (effectively a
controlled or retarded descent, commonly known as "parachuting").  The time
that elapsed between (a) the animal launching itself into the air and (b)
the animal positioning its hindlimbs for landing on terra firma, may
probably have been minimal, and left little time (or need) for tucking the
legs under the body.  As you said, the lift generating abilities of the
plumage were undoubtedly extremely weak.


>          Another thing that caught my eye about the
> newest dromie (?) from liaoning is the length of its
> legs. Could these be used for launching from a perch
> rather than running? Hmmmmm.....

Ahh, but are the two functions (launching and running) mutually exclusive?
Also remember that, if basal dromaeosaurids are any guide (and I suspect
that they are), then the ancestors of birds were probably not strong runners
(i.e. not highly cursorial).

> I end this late night purge of ideas with an amusing
> quote from John Ruben:
> "How is an animal going to have flight feathers on its
> thighs that are half the length of its tail? How could
> it run or do anything with flight feathers sticking
> out of the back side of its leg? It is borderline
> ridiculous." 

I share Ruben's astonishment.  The sheer audacity of Natural Selection in
putting pinnate feathers on the thighs of non-avian theropods!  

(Actually, most birds have feathers on their thighs.  I know certain ratites
(ostriches, rheas) have naked thighs; but I believe cassowaries have
feathered thighs, as do almost every flighted bird I can think of.  Some
birds even have feathers sprouting from the tibia.  Ptarmigans even have
feathers on their feet.)



Tim

------------------------------------------------------------

Timothy J. Williams

USDA-ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163