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


In a message dated 95-12-05 15:33:44 EST, Robert.J.Meyerson@uwrf.edu (Rob
Meyerson) writes:

>Although difficult to prove one way or another, the second possibility
> weaker.  If BCF is correct (I'm on the fence at this point as far as=
> whether I agree with BCF or not), then the wings would have reverted
> into a grasping arm.  The arm would still reasonably show wing-like=
> characteristics, so if there is no evidence of the dromey arm being used
> a wing, then BCF is no longer valid.

The semilunate carpal is a winglike characteristic of dromaeosaurid
forelimbs. Remember that the wings of _Archaeopteryx_ retained a good
grasping function; the digits were all separate and movable (although there
may have been ligamentous locking mechanisms that kept them extended straight
when the wings were being flapped). So a flightless descendant of
_Archaeopteryx_ or a similar dino-bird would likely have retained the
grasping function, too.

The main problem I've always had with the BADD/ground-up scenario is getting
a 20-50 kg theropod with relatively small forelimbs to evolve into a 2-5 kg
dino-bird with grasping wings. It _could_ happen, but in my opinion it is
_far_ less likely than having a 2-5 kg dino-bird with grasping wings to
evolve into a 20-50 kg theropod.