RE: Life of Birds (vertical running)

["Tim Williams" <tijawi@hotmail.com>]

Randall Irmis wrote:

> For dromaeosaurs and troodontids the applications are obvious.  For larger
> animals that are attacking prey with the modified pes, this type of
> locomotion would help keep the individual against the prey while
> running/jumping on to it.  For smaller members of these clades and
> juveniles, the hyperextendable digit could act as a grappling hook to help
> get up a vertical surface in conjunction with this locomotion to get away
> from predators, etc.

Even better: these two scenarios are not mutually exclusive.  The small 
maniraptoran uses the enlarged pedal claw and stiffened tail to help ascend 
trees.  Once up there, it keeps an eye out for ground-dwelling prey.  When 
prey is sighted below, the little predator jumps onto (or close to) the 
prey, using its feathered forelimbs and tail to help negotiate the brief 
descent.  The sickle-claw can then be put to deadly use.

Continue this for long enough, and you reach the _Archaeopteryx_-_Rahonavis_ 
stage of bird evolution.



Tim

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