December 22, 2011
Winter is the season for dinosaur dinners. Both Thanksgiving and Christmas traditionally feature avian dinosaurs as the main gustatory event, and according to paleontological legend, it was this custom that inspired one 19th century naturalist to realize the connection between roasted birds and Jurassic dinosaurs.
Mark Norell, Lowell Dingus and Eugene Gaffney recounted the story in their book Discovering Dinosaurs. “One Christmas Day,” they wrote, “[Thomas Henry] Huxley was carving a turkey for his annual feast. As he dissected the drumstick he was struck by an unmistakable similarity between his Christmas dinner and the fossils of the theropod Megalosaurus back in his office.” From that day on, the story goes, Huxley was convinced that there was a deep genetic connection between dinosaurs and birds. I heard to same story from my Paleontology 101 professor at Rutgers University. It is a charming bit of lore. And it’s also wrong.
I don’t know where the story about Huxley and the Christmas turkey came from. It is one of those stories that seems simply to exist in the academic ether. (Even the Discovering Dinosaurs authors voiced their uncertainty about the tale in their book.) Fortunately for us, though, Huxley’s many scientific papers trace the development of his thoughts about birds and dinosaurs.
Huxley began associating reptiles—including dinosaurs—with birds on the basis of their anatomy in the early 1860s. Both groups appeared to be different variations of a common skeletal blueprint. But Huxley wasn’t thinking about this in evolutionary terms yet. He was primarily interested in the commonalities of structure and did not immediately start drawing evolutionary implications from the anatomical correspondences he recorded. That changed in 1866, when Huxley read the German naturalist Ernst Haeckel’s book Generelle Morphologie, an influential volume that connected organisms in a tangled “tree of life.” In regard to birds and reptiles, at least, Huxley realized that he had already established the basic outline of an evolutionary transition from a dinosaur-like creature—something resembling Compsognathus—to flightless birds and culminating in flying birds.
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. It wasn’t only the small, gracile forms such as Compsognathus that shared skeletal features with birds. Philips himself had been pondering the bird-like characteristics of Megalosaurus even before Huxley arrived, and Huxley’s visit confirmed what Philips had previously suspected. The resulting, updated conception of Megalosaurus was closer to the animal as we know it today—a theropod dinosaur with a short forelimbs, long legs, a long tail for balance and a deep head filled with sharp, recurved teeth.
Huxley’s Christmas revelation is apocryphal. Rather than being instantly struck by the idea that birds and dinosaurs were closely related, Huxley carefully built up an argument over many years that birds evolved from something dinosaur-like. As far as I know, his only sudden realization regarding Megalosaurus involved the rearrangement of bones in Philips’ care at Oxford. And I think this brings up a crucial point often missed or glossed over in accounts of Huxley’s work. Through his efforts to untangle bird origins, Huxley was pivotal in revising the image of dinosaurs into active, bird-like animals. New fossil finds, as well as a new anatomical framework, changed dinosaurs from ugly beasts into graceful, unique creatures during the 1870s, thanks at least in part to Huxley’s efforts. (Too bad that succeeding generations of paleontologists would unravel this vision by casting dinosaurs as dumb, cold-blooded reptiles.) Even if Huxley didn’t say birds are dinosaurs, he certainly made dinosaurs more bird-like.
For more information on Huxley’s thoughts on dinosaurs and birds, please see my paper “Thomas Henry Huxley and the Reptile to Bird Transition” and chapter 5 of my book Written in Stone.
Huxley, T.H. 1870. Further Evidence of the Affinity Between the Dinosaurian Reptiles and Birds. The Quarterly Journal of the Geological Society of London, vol. xxvi. 12-31
Norell, M., Dingus, L., Gaffney, E. 2000. Discovering Dinosaurs: Expanded and Updated. Berkeley: University of California Press. p. 11
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