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

Re: 11th specimen of Archaeopteryx

Don Ohmes <d_ohmes@yahoo.com> wrote:

> I am not sure what you mean by "over-extension", or why you wish to avoid
> it, but this point stands -- a tree-roosting, ground-foraging animal does
> not *require* a "long, reverted first toe", especially when parachuting down
> is an option -- as to perching, Wood Ducks (Aix sponsa) have webbed feet,
> and both nest and intermittently roost in trees, seemingly coping well, even
> challenging woodpeckers for nest sites.

Good point.  Even more notable is that the wood duck does this without
the benefit of a long hallux.  Although the hallux is reversed, it
tends not to be used for perching.  It's my understanding that the
wood duck favors very sturdy branches, which it grips with the three
forward-pointing toes.

> It is a lifestyle that is under-appreciated relative to flight evolution in
> small theropods, in my view -- trees are generally easier to climb than to
> get down from, and a parachuting capability is advantageous.

Again, agreed.  The old "trees-down" versus "ground-up" dichotomy
doesn't give enough credit to the ecological versatility that
paravians were possibly capable of.  I don't picture elevated
vegetation as places that basal paravians roosted or nested in; more
as a source of food.

> The potential to evolve wings and an Archaeopteryx-style body is obvious.

As a presumed insectivore, the forelimbs of _Archaeopteryx_ were not
much use for catching insects or other small prey.  So the forelimbs
were freed up to be used for other things - such as aerial locomotion
or display (or both).

The phylogeny provided in the _Xiaotingia_ paper further suggests that
the line to modern birds included herbivores (or at least omnivores).
This provides further support to the view that targeting seeds and
fruits was much more important in the evolution of avian flight than
carnivory or predation.