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

Re: Sauropod Necks



I know I shouldn't bite at this Matt-bait, but here are a few "BRIEF" comments (well, not really all that brief).

Scott Hartman says:

But actually, the dinomorph project itself is not yet very scientific.

But scientific enough to get published in Science? I would argue the dinomorph project is scientific because it allows us to test hypotheses, propose new ones, make predictions, and, when they get it out to everybody like they plan, it is and will be repeatable. And the results are definitely falsifiable.


Don't get me wrong, I think it is by far one of the most promising ideas for research into functional osteology, and I think the results published so far are probably pretty good. But no one has published the results of a study using the dinomorph techniques on an extant animal with a known range of motion, in order to asses the accuracy of the results. Until then, we are peeing into the proverbial wind, with this phenominally powerful tool on our hands, but no metric to correlate it against.

Although they haven't published it, they did test DinoMorph out on a giraffe cervical series, and they achieved similar movements that are seen in living giraffes. I know they presented this at one of the SVP meetings, I believe the 1996 one in New York, but unfortunately this result is not printed in their abstracts (which is too bad). In any case, more of this sort of work is planned to test the accuracy of the model.


Furthermore, Parrish and Stevens recognized that for all vertebrates, the two areas of motion between verts occur at the zygapophyses and the centra. If any of you on the list have ever taken a human anatomy course, you have worked with models or real vertebrae that you can connect together and play with the motions. Has anyone ever connected neck verts together and gotten a total strange neck angle? With the soft tissue missing, can the verts be made to bend into grotesque contortions? And human verts don't have the ball-and-socket joints of sauropods that further constrain possible motions.

Parrish and Steven are just linking the bones together based on joint geometry with a few restrictions based on analysis of extant vertebrate necks. This is the most basic way of explaining what DinoMorph does and its a basic exploration tool rooted in the joint surfaces of the verts. What "metric" is lacking here? "Peeing into the wind"??????

Let me take this moment to suggest, if anyone decides to do this, that this is one of those rare opertunities in paleontology were we could do a double-blind study.
Get a student who knows the dinomorph software, but isn't an expert in osteology (specifically, someone who couldn't determine the species from a cervical series) and have them take and enter the measurements from a wide range of large and medium sized vertebrates.

Sure. And when desktop versions of the software become available, this can be done.


However -- Parrish and Stevens were just as surprised as everyone that the necks of the diplodocids were far more horizontally oriented than predicted. It's not as if they went in with a bias looking for a particular neck orientation. They had this new tool, they used it to explore the feeding envelopes of sauropods, and they got an unexpected result that they have shared with everyone and showed how they got it.

And with all the popular media depictions of sauropods with vertical necks, how could you be sure your subject for the double-blind experiment, a person not chosen at random because they have to be familiar with the DinoMorph program, would be unbiased toward the vertical orientation? How is this double-blind?

The point is, the movements between the vertebrae are being constrained in the program by the morphology of the joint surfaces, not by a predisposed bias.

See what comes out. If I had any grant money, I would personally donate it to see what the results would be.

Please do! =) You can send me a big old wad of cash anytime -- do I have to show all my expenses? =P


Matt Bonnan

"Come on and wring my neck ..."
-- Faith No More, "Midlife Crisis"
________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com