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RE: _Microraptor zhaoianus_
Could we look at this from the BCF point of view, and say that this
form could be a bird descendant whose foot is reverting back for
ground-dwelling, and that the feathers are "degenerating" being no longer
needed for flight. Or would this be a "just-so" story that is too
unparsimonious? Seems like you could look at it either way, but perhaps
other evidence imparts some directionality here, one way or the other.
Just speculating, Ken
From: "Thomas R. Holtz, Jr." <firstname.lastname@example.org>
To: <email@example.com>, "Dinosaur mailing list" <firstname.lastname@example.org>
Subject: RE: _Microraptor zhaoianus_
Date: Thu, 7 Dec 2000 09:57:55 -0500
> From: email@example.com [mailto:firstname.lastname@example.org]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,
(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.
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
College Park, MD 20742
Phone: 301-405-4084 Email: email@example.com
Fax (Geol): 301-314-9661 Fax (CPS-ELT): 301-405-0796
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