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Re: How did dromaeosaurs use their arms?
Jaime "James" A. Headden wrote a response to my question about how dromaeosaurs
used their arms. I would like to make some questions, which I'll place under
short pieces of Jaime's text:
> Ostrom (1976) showed the arm supination/pronation
> was limited, due largely to the wrist, whereas in less
> derived theropods, such as allosaurs, it was more
> capable of s/p. Such ways, the wrist was constantly
> held in line with the proximal ends of the
> ulnae/radii. Such a structure would allow the wrist to
> fold easily against the forearm, pulling it out of the
> way, and allowing sufficient leverage for a powerful
> forward "swap" of the hand, to be simplistic.
Supination/pronation means folding the wrist upwards and downwards, not
> is turned dorsomedially, and the first phalanx was
> "twisted" slightly along the axis with the distal
> articular turned medially, so that the digit would
I didn't quite understood this. I know that "dorsal" means the upper half of an
animal, "medially" probably something like "in the middle" and "in axis with
something" in turn that a thing has the same direction as something else.
> have faced partially inward with the arm extended, or
> down when flexed. The other two digits would have
> faced down in the former, and inward inward in the
> latter, though the third finger may have been much
> more mobile.
What do we mean here with "inward" and "down"? I think that if I hold my manus
horizontally, so that the inside of it faces down, the fingers II-V of mine
face BOTH down AND inward. The thumb of mine, in turn, faces as wuch inward as
it faces downfard. I am not trying to point out any kind of functional
analogies here, just making sure that we mean the same things with same words.
Soittoäänet ja ikonit matkapuhelimeen! http://www.iobox.fi/