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Re: a little background



Graydon (graydon@dsl.ca) wrote:

<What do you call the big sickle claws?  They're way overkill for
comparably sized critters.>

  Overkill? For what? No one has evidenciary proof except for
*Velociraptor* using the claw for evisceration -- on a 8 ft
*Protoceratops*. This _proves_ nothing about the use of such a claw in
other dromies or even in *Velociraptor*, just one use. Many perching birds
have such claws ... but do not use them to eviserate larger prey than
themselves.

<Dinurnal owls and bats have huge eyes but it's a retained character from
nocturnal ancestors; all troodonits were not necessarily crepuscular but
the lineage is derived from that mode of life if the eyes are accepted as
evidence of a crepuscular lifestyle at all.>

  Yes, but many non-crepuscular animalsd have these. While it's logical
that the enlarged orbits indicate a crepuscular habit, this id not
indicated by any other fact. Many animals that are diurnal, regardless of
ancestry, especially Primates and other primatomorphs, the diurnal flying
foxes, and generally small mammals and most birds, have fairly large
orbits. This is true of parrots, most of whom are diurnal ... the orbit is
positively gigantic, but exposure of the eye within the lid is small ...
whereas aardvarks are nocturnal and have very _small_ eyes. Orbit size is
not neccessarily an indication of eye or pupil size, and it's really the
latter which counts most in nocturnal/crepuscular arguments, and
unknown/unprovable in the fossils in question.

<I do wonder if the metatarsus is short as an [assistance] to power
transmission in using the sickle claws; it wouldn't apply to oviraptorids,
though.>

  Sickle effect requires the flexor tendons ... which are connected to the
rear-tibial muscles, which have little to do with the ankle itself and
therefore the metatarsus. It acts only as a lever for the pes during
locomotion, and the shortness of the second metatarsal indicates the lack
of effect in the second toe to locomotion, removing effect of the
metatarsus on the second digit. At least according to present research (I
admit to needing more myological knowledge).

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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