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RE: _Microraptor zhaoianus_

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Jeff Hecht
> Tom Holtz wrote
> >*The metatarsal I and pedal digit I are very distally placed, and the
> >penultimate phalanx of each of the toes is elongate: Xu et al. interpret
> >this as indicating a climbing habit.
> Xu says that the foot structure indicates a ground-living ancestry.

(Specifically, Xu was referring to the arctometatarsalian nature of the foot
in this context).

> Suppose the common ancestor was a Microraptor-like animal
> adapted for predation both on the ground and in trees, so it never
> truly gave up ground-dwelling but spent a significant part of its
> life in the trees. The ability to glide down from the trees might
> offer an evolutionary benefit, giving an advantage to any dino-bird
> with flight feathers. Perhaps it started by extending pouncing range
> from tree limbs.
> It's just a thought, but I think Xu may be onto something.

Indeed.  Wish I had proposed something like that back at SVP 1994.  Oh,
wait... :-)

(To be fair, others have thought of similar aspects too: recent studies of
the proportiopns of the toes and fingers of maniraptorans near or just past
the origin of birds show a decidedly intermediate aspect to their
proportions: neither fully arboreal nor fully cursorial).

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796