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Re: Major new paper on dromaeosaurids, with other significant maniraptoran info
In the history of life on Earth, relatively few predators have required
grasping hands with opposable thumbs for catching prey.
True. But... in the history of life on Earth, relatively few predators are
bipeds. Predatory mammals are quadrupeds, in which the forelimbs are also
used for locomotion. The first dinosaurs were bipeds, which 'freed-up' the
forelimbs for use in predation: siezing, holding and processing prey.
Predatory birds often have a pes designed for grasping. Of course, there
are exceptions: the secretary bird simply pins prey to the ground with its
If groups of _Deinonychus_ did indeed hunt larger prey --
_Tenontosaurus_, apparently -- it is entirely possible that these
dromaeosaurs were unique in these aspects of their hunting style.
I agree with this 100%. The two-handed grasping method proposed for
_Deinonychus_ seems perfect for catching and holding large prey. I am just
not convinced that small maniraptorans like _Microraptor_ and
_Archaeopteryx_ used their arms in the same manner.
Certainly dromaeosaurs could have hooked and snatched up small prey in
one hand with ease, or they could have slapped their clawed hands onto
small prey items prior to delivering killing bites.
I'm not certain that hooking and snatching prey was as easy as you make it
out to be, given the length and relative immobility of the fingers, and the
altered range of motion of the manus courtesy of the 'swivel-wrist'.
Maniraptorans made some big changes to the architecture of the distal
forelimbs, and none of them helped in their ability to grasp and manipulate
small prey. Quite the opposite, in fact.
Most predators today don't even use their forelimbs to catch their prey,
By and large, modern reptilian and mammalian predators are quadrupeds. As
for modern birds... their options are much more limited.
Two handed scooping doesn't sound far fetched to me, as either hand
will snag the intended food item and quickly clap toward the opposing hand
before the animal has a chance to get away. Dromaeosaurs certainly had
long forelimbs, and I would expect they were good for something (aside from
flying and/or gliding in the smaller varieties). What aspect of this two
handed scooping scenario troubles you?
Sure, a two-handed grasping motion might work for snagging and holding prey.
But what was wrong with the grasping and raking manus present in early
theropods? The primitive theropod manus was specialized for handling prey.
Maniraptorans diverged from this condition.
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