April 17, 2012
Sauropods were swamp monsters. At least, that’s what books, movies, and illustrations taught me when I first encountered the huge dinosaurs. If Diplodocus and Brachiosaurus didn’t actually spend most of their time in the water, then the dinosaurs always stayed close to watery refuges where they could escape from Allosaurus and other predators.
But starting in the 1960s, a renewed scientific interest in dinosaurs overturned this cherished imagery. Sauropods were wholly terrestrial creatures. These giants did not possess any features related to an aquatic or amphibious lifestyle—Apatosaurus and kin were often plunked down into bogs and lakes in reconstructions because that environment seemingly answered nagging questions about the biology of these animals. But early 20th century paleontologists didn’t think that all sauropods were equally adept at life in the water. Rather than take the line that all sauropods were skilled swimmers, paleontologists identified at least one Jurassic sauropod that probably spent more time on land.
In 1920, a trio of American Museum of Natural History scientists published a pair of short papers on the sauropod Camarasaurus. This dinosaur, with a blunt head and spoon-shaped teeth, was one of the better-known members of the classic Morrison Formation fauna, and the AMNH paleontologists had just completed a major reexamination of the dinosaur’s remains. In the first note, Henry Fairfield Osborn and Charles Mook briefly summarized the results of their study, and in a second, accompanying missive, William Gregory outlined the dinosaur’s life habits.
Camarasaurus didn’t seem suited to a life wallowing in a Jurassic lake. While Gregory mentioned that the dinosaur “might well have been an efficient wader,” the dinosaur was also “positively devoid of special adaptations for swimming.” The dinosaurs limbs, shoulders and hips were clearly suited to supporting the animal’s bulk, and Gregory considered the “relatively small and feeble” tail of Camarasaurus to be of no help in swimming. While Gregory did waffle on the habitat the dinosaur preferred, the overall picture was of a relatively straight-limbed dinosaur that carried its body high off the ground. Sauropods did not drag their bellies through the Jurassic mud, as other paleontologists had suggested under the supposition that sauropods were like lizards or crocodiles, writ large.
The following year, when Osborn and Mook published their massive revision of sauropods collected by Edward Drinker Cope, they similarly cast Camarasaurus as a dinosaur that was “terrestrial in gait but adapted to an amphibious life.” And the plates of that paper present some of the restorations and reconstructions previously mentioned in the PNAS papers. A model of Camarasaurus, created by artist Erwin Christman under Gregory’s direction, showed the dinosaur walking on land with slightly bent forelimbs, similar to how the museum mounted its great “Brontosaurus” skeleton years before. Christman and Gregory also collaborated on a pair of skeletal reconstructions—one with the head of Camarasaurus held high, and the other in a droopy pose, with neck and tail slung low.
Osborn, Mook and Gregory’s insistence that Camarasaurus was an amphibious dinosaur, or at least frequently waded, is puzzling. The paleontologists didn’t justify this part of their argument. Sauropods were simply considered synonymous with warm, luxuriant swamps. Contrary to this belief, the experts explicitly pointed out evidence that Camarasaurus walked tall and had a skeleton well-suited to holding up the animal’s weight while walking on land. Even before the “Dinosaur Renaissance” forever changed dinosaurian imagery, early 20th century paleontologists were already cataloging the same evidence. They just saw that evidence differently, in the context of a lazy Mesozoic world filled with shuffling, basking sauropods.
Gregory, W.K. 1920. Restoration of Camarasaurus and life model. PNAS. 6, 16-17
Osborn, H.F., Mook, C.C. 1920. Reconstruction of the skeleton of the sauropod dinosaur Camarasaurus Cope (Morosaurus Marsh). PNAS. 6, 15
Osborn, H.F., Mook, C.C. 1921. Camarasaurus, Amphicoelias, and other sauropods of Cope. Memoirs of the American Museum of Natural History, new series, 3, 247-387 (plates LX-LXXXV).
Taylor, Michael P. 2010. Sauropod dinosaur research: a historical review. pp. 361-386 in: Richard T. J. Moody, Eric Buffetaut, Darren Naish and David M. Martill (eds.), Dinosaurs and Other Extinct Saurians: a Historical Perspective. Geological Society of London, Special Publication 343.
August 23, 2010
A few weeks ago, someone decapitated the dinosaur standing outside Norman, Oklahoma’s only Sinclair station. The sculpture—put in place five years ago and named “Dino”—was a beloved local landmark, and fortunately the head was eventually recovered. This wasn’t the first time a dinosaur’s head has been stolen, but, in an odd way, it is a case of vandalism imitating one of the most frustrating aspects of dinosaur paleontology.
More often than not, sauropod dinosaurs are found without heads. Whereas their thick limb bones and complex vertebrae have often made it into the fossil record, their small and often fragile skulls are exceedingly rare. Any discovery of a sauropod skull is cause for celebration.
The rarity of sauropod skulls has had a major influence on what scientists have thought some dinosaurs were like. Take, for example, the search for the head of Apatosaurus as recounted by Keith Parsons in the book Drawing Out Leviathan: Dinosaurs and the Science Wars. Even though O.C. Marsh had published a full restoration of the dinosaur—called Brontosaurus at the time—in his famous reference book The Dinosaurs of North America, no skull had actually been found. What kind of noggin Brontosaurus had was up to speculation, and Marsh used a Brachiosaurus skull (thought to belong to Camarasaurus at the time) found at a different site to complete his restoration.
Marsh was reluctant to create a reconstruction of his nearly complete sauropod, but the next generation of paleontologists was not so reticent. The American Museum of Natural History, the Field Museum, and the Carnegie Museum all competed with each other to find exquisite specimens of large, Jurassic dinosaurs suitable for mounting in their exhibition halls. Of these institutions, the Carnegie had some of the best luck, including the discovery by fossil hunter Earl Douglass of the fossil jackpot in northern Utah known today as Dinosaur National Monument.
Among the most promising specimens Douglass found was what appeared to be a nearly-complete Brontosaurus. The first parts to be uncovered were portions of the hip, hind limb and spine, but perhaps—all the way at the end of the vertebral column reaching into the rock—there was a skull, too. As Douglass began to uncover the skeleton in September and October of 1909, he frequently wrote back to the Carnegie museum staff that he was confident that he would eventually find a skull at the end of the long chain of vertebrae, but in a November 11 letter, he reported defeat. The dinosaur’s neck had been thrown backwards over the middle part of its body—a very common condition among dinosaur skeletons—and when Douglass excavated the front portion of the neck he did not find any skull. The neck ended just a few vertebrae short of where the head should have been, a discovery Douglass reported was “disappointing and sickening.”
Doulgass continued his work at the Utah site, eventually recovering a Diplodocus skull, and it was this skull that led the fossil hunter to wonder if he had been looking for the wrong thing all along. In a letter to the museum’s director, W.J. Holland, Douglass wondered, “has a skull or part of a skull of Diplodocus ever been found in such a position that we can be positively sure that it belongs to Diplodocus?” The particularly robust Diplodocus skull Douglass had found was in close association with the Brontosaurus skeleton at the quarry, so, just maybe, the skulls which had been called Diplodocus really belonged to a different dinosaur. Douglass’ supervisor was clearly struck with this line of argument. In December 1914 Holland delivered a lecture to the Paleontological Society of America in which he asserted that the large “Diplodocus” skull Douglass had found really belonged to the Brontosaurus body. At long last, Brontosaurus had a head.
Curiously, however, Holland did not immediately install a head on the Brontosaurus at the Carnegie Museum. The skeleton, given the designation Apatosaurus today, remained headless for almost 20 years. Why Holland was so reluctant to install a skull on the skeleton is uncertain. As Holland would later suggest in his own writings, that Marsh was wrong seemed more certain than Holland’s own selection of the Diplodocus-like head for his Apatosaurus, and as long as Douglass was working in the quarry it was possible that a skull found connected to an Apatosaurus skeleton would turn up. If such a specimen was found and Holland was wrong it would certainly be an embarrassment, and in 1934 someone decided to fix the situation by placing a Camarasaurus head on the Carnegie’s Apatosaurus skeleton (especially since the paleontologist C.W. Gilmore was coming to the museum explicitly to examine the skeleton). At the time it was believed that Apatosaurus and Camarasaurus were more closely related to each other than either was to Diplodocus anyway, so it seemed like the reasonable position to take despite the opinions of Douglass and Holland. It would not be until 1979, after an in-depth study by paleontologists David Berman and John McIntosh showed that Holland had been right, that Apatosaurus would be mounted with the right head.