I spent most of my childhood with books about dinosaurs that played up the ancient beasties as overgrown lizards. The connection between dinosaurs and birds, while kind of flipping obvious once somebody points it out, was not much discussed among laypeople until I was in my teens. (That would be the 1990s, FYI.)
But, among scientists, the idea of a dinosaur-bird relationship is nothing new. In fact, Thomas Henry Huxley was making that connection back in the 1860s. On the Dinosaur Tracking blog, Brian Switek tells the fascinating story of how Huxley started to realize that dinosaurs and birds were related—a discovery that's all the more impressive because he figured it out without the help of some of the key transitional fossils we have access to today.
Huxley did not suggest that birds were the direct descendants of dinosaurs. So much geologic time was unaccounted for, and so few dinosaurs were known, that Huxley could not point to any known fossil creature as the forerunner of birds. Instead he made his argument on anatomical grounds and removed the issue of time. Dinosaurs were proxies for what the actual bird ancestor would have been like, and flightless birds (such as the ostrich and emu) stood in for what Huxley thought was the most archaic bird type. (We now know that Huxley got this backwards—the earliest birds could fly, and flightless birds represent a secondary loss of that ability.) As Huxley went about collecting evidence for his case, though, he also gave dinosaurs an overhaul. They were not the bloated, plodding, rhinoceros-like creatures that Richard Owen had envisioned. Dinosaurs were more bird-like than anyone had imagined.
In October of 1867, Huxley met with John Philips, an English geologist and a curator of Oxford’s museum. As Huxley related in his 1870 paper “Further Evidence of the Affinity Between the Dinosaurian Reptiles and Birds,” Philips wanted to discuss details of marine reptiles called ichthyosaurs in his museum’s collection, but as he and Huxley made their way over toward the displays they stopped to look at the bones of the carnivorous dinosaur Megalosaurus. Then Huxley spotted something peculiar:
As Prof. Phillips directed my attention to one after the other of the precious relics, my eye was suddenly caught by what I had never before seen, namely, the complete pectoral arch of the great reptile, consisting of a scapula and a coracoid ankylosed together. Here was a tangle at once unravelled. The coracoid was totally different from the bone described by Cuvier, and by all subsequent anatomists, under that name. What then was the latter bone? Clearly, if it did not belong to the shoulder-girdle it must form a part of the pelvis; and, in the pelvis, the ilium at once suggested itself as the only possible homologue. Comparison with skeletons of reptiles and of birds, close at hand, showed it to be not only an ilium, but an ilium which, though peculiar in its form and proportions, was eminently ornithic in its chief peculiarities.
Earlier naturalists had made a mistake. They had misidentified the shoulder girdle, and one part of what was thought to be part of the shoulder was actually part of the hip. Another strange piece, previously thought to be a clavicle, also turned out to belong to the pelvis. This rearrangement immediately gave the dinosaur a more bird-like character.
If you look at the bottom of the image at the top of this post, you can see how much the re-arrangement of megalosaurus' parts changed our conception of what the whole creature looked like. Where other scientists saw a lumpy, obese crocodile, Thomas Henry Huxley saw a saber-toothed chicken.
Image: Ballista via CC
Christie Aschwanden is a science journalist. Last month, she joined a lot of other science journalists at the National Association of Science Writers conference and gave a short Ignite presentation about why people get angry when presented with evidence that their beliefs are wrong. She's posted a storyboard of the presentation to The Last Word on Nothing blog. It's definitely worth a read.
I’m married to an amazing guy. Dave is like those honeybees that always know the way back to the hive. Me, I’ve gotten myself lost in the Hearst building. We’ll be hiking and we’ll come to a split in the trail and I’ll point one way and say, we need to go here. And Dave will say no, actually, this is the right way (as he points in the opposite direction). And I’ll insist that, no, this is the way.
And then he’ll point out that my way peters out below some cliff face. Which only pisses me off. The more evidence he shows me that I’m wrong, the more insistent I become — I’m right and he’s wrong. And it’s not just me. This political scientist named Brendan Nyhan at Dartmouth has documented what happens when you show people evidence that their beliefs are wrong.
So when Dave tells me that his way is right and mine is straight up a cliff, I think, oh yeah? Well I’m smart, independent and capable, so therefore I’m correct. I would never point us in the wrong direction. See, it’s never really about the hiking trail. It’s about some bigger story you’ve told yourself. I’m not taking issue with Dave’s direction. I know he’s right. But the factual mumbo jumbo he’s showing me clashes with the story I’ve told myself. I don’t like what it says about me.
Ouch. I know I've had experiences very much like that one before. I'm sure you have, too. What we believe about ourselves affects how we react to people who show us that we are wrong about something.
What's interesting to me about this, though, is that I don't react this way when I prove my own beliefs wrong. For instance, when I hear about a new study, and then have to dig into the evidence that presents a different perspective than the one I originally came up with. In fact, I kind of like doing that. But, then, challenging my own beliefs makes me feel more capable. It fits the story I tell me about myself.
I came away from this thinking two things. First, maybe we all need more opportunities to comfortably challenge our own ideas. (Although, I'm not sure how to create that space. Especially to cover the things that really matter.) Second, we all (me included) need to remember that being questioned—and being wrong—doesn't mean there's something wrong with us.