[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Emus a Model for Dinosaurs?
So if the center of locomotion shifts in neornithes forward from acetabulum
to the knee, as a compensatory shift in the center of mass / gravity (due
primarily to a reduction in the caudal series ), can we assume Caudipteryx
grade animals also may have moved via a knee driven mechanism? Is there
evidence of a reduced 4th trochanter or other modifications in the
morphology of the femora that might support this?
As you point out, although the limb segment length / stride length may vary
amongst taxa (both living and extinct), the relative orientation of the pes,
when contacting the subtrate should be similar, ratites serving as one of
the best living analogs ( and visual models, from the artist's perspective )
around today. Rob Gaston produces a nice cast emu foot, I've used one for
reference in the studio for years !
In all fairness, "quite different" is relative. Neornithes limb mechanics
are very similar to dinosaurs in their articular contacts (even accounting
for fusion of the metapodia and the tibiotarsus). Limb excursion (as Tim
and Jim and Jim noted) is generated somewhat differently (shifting from
the primitive acetabulum based locomotion to the more derived knee-based
limb excursion), but the maximum and minimum ranges of motion are very
similar, including off-axis motion (which is important). And the actual
plantar surface of the feet (and the internal bones, tendons, and
ligaments that create it) of modern cursorial dinosaurs are almost
identical in how they function to their Mesozoic brethren. Certainly much
better than using most extant placental feet to understand the
biomechanics of Mesozoic mammal trackways.
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333
To: firstname.lastname@example.org; email@example.com
Sent: Fri, 27 Oct 2006 8:41 AM
Subject: Re: Emus a Model for Dinosaurs?
Andreas Johansson wrote:
Aren't neornithine leg mechanics quite different from those of
Check out the new AOL. Most comprehensive set of free safety and security
tools, free access to millions of high-quality videos from across the web,
free AOL Mail and more.