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Re: You could lead a sauropod to water ...

Jonathan R. Wagner wrote:

... a whole heck of a lot!  Wow, and thanks for throwing your hat in there.

"Careful, there is more to morphology than simple function (although,
I suppose one might argue that there is no morphology without function). It
would be meaningful to explore the phylogenetic signal within the foot
structure of these taxa as well."

Agreed, and this is being done. However, as part of what I'm doing with the phylogenetic signal is tied in with another researcher, I will politely decline to say more until a further date. All I can say is that there is an interesting phylogenetic signal in sauropod feet.

For the simple function from morphology, it is important to note that most folks have just treated the feet of sauropods like slabs of meat on the ends of the limbs that propped them up. The late Jim Jensen actually said in a paper on sauropod rearing that the contribution of the sauropod manus and pes to locomotion was like "the rubber stopper at the end of a crutch." (Jensen, 1988). No joke. Nor, as it turns out, is this a correct assessment.

While it may seem rather odd to many on this list, many dinosaurs, not just sauropods, are poorly understood from a functional perspective. Many things of functional morphology, especially in big, heavy, pain-in-the-ass animals like sauropods, are assumed and for good health reasons -- some answers may require lots of heavy lifting. So far, I've been lucky in avoiding serious back injury. But that is what you're up against even for simple "it moved like this or that" or "it could not do this or that" functional assessments. I am not alone in doing this stuff -- anyone who works on many of the ornithischian or theropod dinosaurs is in the same boat. Nor am I blaming anyone for making certain locomotor assumptions -- sometimes that's all you can do. Case in point: the Alamosaurus specimen at NMNH has salt disease -- you cannot even touch the bones without damaging the limb specimens. So you take what measurements you can and try to imagine how the limb might fit together. Again, this is where newer computer imaging technology would come in ...

"Phylogeny can help us
reconstruct the common starting point, not only morphologically, but also
functionally, and therefore strengthen our hypotheses and point out
inconsistencies in them."

Agreed again. This is why I looked at prosauropod and theropod limbs as well so I had some outgroup comparisons. Sauropods are still weird animals, even among dinosaurs. For the Shunosaurus and Brachiosaurus questions, again I'm afraid I'll have to be quiet on that stuff for now.

Thanks for bringing phylogeny into this. It's important to realize that we never make our functional assessments in a vacuum, and that phylogeny and function play important interchangeable roles in our assessments of locomotion and other dinosaur behaviors.

Matt Bonnan

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