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I am a politically-progressive, ethically-herbivorous anthropoid pursuing a paleontology education in the Los Angeles Basin. I am largely nocturnal, have rarely been photographed, and cannot thrive in captivity.

23 April 2011

Listening To Pterosaurs

Pterosaurs keep pecking at my brain. For months now, they've been haunting me, and it's felt like they were trying to raise a question other than, "who're you calling a dinosaur, bub?" I've been itching to say something on this blog about these fascinating animals, but I couldn't quite put my distal phalange on just what it ought to be.
Credit: Mark Witton, U. of Portsmouth

But Mrs. T has changed all that. Or maybe she's just clarified it for me.

It's her egg that did it. The poor girl died while pregnant, and as she decomposed, her egg was expelled from her body, then fossilized in its own right. And it turns out the egg isn't what we'd expected at all.

For years, researchers thought the reproductive cycle of pterosaurs was like that of modern birds: i.e., they laid eggs with shells that hardened on contact with air; they sat on nests and took care of hatchlings. But we now have solid evidence that that wasn't the case at all.

Mrs. T's egg was small and soft-shelled, like that of modern lizards and snakes. These animals generally bury their eggs after laying them, and the eggs receive moisture and nutrients from the surrounding soil. And what's more, the young reptile hatchlings are far more developed and self-sufficient than baby birds. The similarity between modern reptile eggs and pterosaurian eggs (or, at least, Darwinopterus eggs) indicates that pterosaur reproduction was more reptilian than avian.

In short, pterosaurs weren't dinosaurs, which means they weren't birds, either. And that, in turn, means that modern comparative anatomy tests on pterosaur flight that have tended to exploit and vivisect modern birds were headed in the wrong direction, a fact noted by a rising star of pterosaur paleontology last March:
Avian biomechanical parameters have often been applied to pterosaurs in such research but, due to considerable differences in avian and pterosaur anatomy, have lead to systematic errors interpreting pterosaur flight mechanics. Such assumptions have lead to assertions that giant pterosaurs were extremely lightweight to facilitate flight or, if more realistic masses are assumed, were flightless. Reappraisal of the proportions, scaling and morphology of giant pterosaur fossils suggests that bird and pterosaur wing structure, gross anatomy and launch kinematics are too different to be considered mechanically interchangeable. Conclusions assuming such interchangeability—including those indicating that giant pterosaurs were flightless—are found to be based on inaccurate and poorly supported assumptions of structural scaling and launch kinematics.
The take home point here -- the question the pterosaurs haunting my dreams have been trying to raise -- is, how efficacious is animal testing in paleontology anyway?

I've blogged before about the moral quandary I'm slowly approaching in my studies. I must confess to having set out upon this path with more than a little naivete. Paleontology appealed to me because it allowed me to study animals and evolution without having to hurt any living beings. When I found out this wasn't true, I began cultivating an interest in paelobotany that might still claim my future. For all my paleo-nerdiness and love of science, I am unwilling to harm nonhuman animals, even indirectly, in my pursuit of knowledge.

Still, reliance on modern animals is far less common in paleontology than it is in other life sciences, and I think that with some due diligence and activist pressure from within, the paleo community can and will do a better job of monitoring their sample sources. If I'm lucky, I may get to play a role in that one day.

The incompatibility of pterosaur and bird anatomies can help highlight the ethical point. Pterosaur researchers had become so enamored with birds (not that I blame them!) that they failed to see pterosaurs for who they really were. And this meant, not incidentally, that many modern birds went under the knife in those researchers' quest to crack the "mystery" of giant pterosaur flight.

We now know that those poor birds' sacrifice was in vain. Analogies with birds were taken too far, both scientifically and ethically. Pterosaurs were not dinosaurs, and that means they weren't bird-like, either. We can now add bird experimentation in pterosaur research to the long list of animal testing that was pointless, and arguably more cruel because of it.

I don't want to make too much hay out of it, though. As I've already written, many paleo labs use salvaged animal remains from ethically-clean sources, and absent any evidence to the contrary, I'm assuming this has been generally true of pterosaur research, as well. I'm still heart-broken, however, at the prospect that at least some birds used in that research over the years were the victims of commercial suppliers to whom the birds were mere commodities, not beautiful living things with something important to teach us. Again, if there is cruelty and blame to be assigned here, I'm inclined to place it on the suppliers, not the researchers.

The pterosaurs are calming down now. I think they're happy that I finally figured out what they were trying to say: "we are proof that animal testing is often pointless."

I love them now more than ever.

3 comments:

  1. That's really interesting. I can see how researchers easily fell into the trap of thinking that pterosaurs are similar to birds, but I didn't know there was so much (or any) animal testing involved in paleontology. Thanks for an interesting post, and for sparking some renewed interest in dinosaurs. Glad to see you are back!

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  2. Really interesting, I didn't know animal exploitation was still a big issue in paleontology.

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