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The original AMNH mount of Brontosaurus, reconstructed in 1905. Image from Wikipedia.

“Brontosaurus” will always be special to me. The shuffling, swamp-dwelling dinosaur never really existed, yet, for my younger self, the Jurassic behemoth was an icon of everything dinosaurs were supposed to be. The skeleton mounted at the American Museum of Natural History is what really hooked me on the sauropod. When I first visited the skeleton in the late 1980s—before the museum’s dinosaur halls were renovated in the late 1990s—I was astonished. I had seen illustrations of Brontosaurus before, but seeing the animal’s actual bones was a transcendent experience for me. I already liked dinosaurs, but after standing in the shadow of those column-like limbs and intricate vertebral column, I loved dinosaurs.

Today we know that the specimens once assigned to Brontosaurus excelsus really belonged within the genus Apatosaurus. That issue was settled decades before I was even born, although museums and paleontologists themselves were slow to adopt the change. (It wasn’t until the proper head of Apatosaurus was rediscovered—the specimen was excavated at Dinosaur National Monument in 1909 but confused for a Diplodocus skull for decades—that the move to publicly shun Brontosaurus started in earnest.) Indeed, in 1903 paleontologist Elmer Riggs recognized that Brontosaurus excelsus was extraordinarily similar to the skeleton of another sauropod, named Apatosaurus ajax. Both had been named by Yale paleontologist O.C. Marsh at the height of the Bone Wars era, when many dinosaur specimens, no matter how subtle their differences, were given a new genus or species designation. In this particular case, the fact that the Apatosaurus ajax specimen came from a relatively young animal and the Brontosaurus excelsus specimen was an older animal led Marsh astray. Both forms, Riggs concluded, belonged to the same genus, and Apatosaurus had priority since it was named first.

The American Museum of Natural History mount went up in 1905. The dinosaur was promoted as Brontosaurus, not Apatosaurus. Even though Riggs’ case would eventually win out, AMNH paleontologists Henry Fairfield Osborn and William Diller Matthew didn’t agree with the name change. Exactly why Brontosaurus was allowed to live on—much to Riggs’ frustration—is unclear. But all these little quirks of nomenclature and procedure had a major influence on the popularity of Brontosaurus over Apatosaurus. The AMNH mount was the first reconstruction of this dinosaur ever attempted, and in 1905, it was one of a kind. (The original material Marsh used to describe Brontosaurus was held at Yale, but Marsh never made an effort to publicly display the partial skeleton his crew found at Como Bluff, Wyoming. The specimen, carrying a Brontosaurus name plate and the wrong head, was not reconstructed at Yale until 1931.) The AMNH Brontosaurus mount was the introduction of sauropods to the fascinated public.

William Diller Matthew recounted the process of mounting his museum’s Brontosaurus in an American Museum Journal article and a news item for the Independent. The skeleton was a Frankenstein. The principal part of the mount was an incomplete skeleton found near the Nine Mile Crossing of the Little Medicine Bow River in Wyoming. This one site yielded most of the vertebral column, all the ribs, elements of the shoulders and hips, and a few portions of the limbs from the single sauropod. But quite a few parts were missing, so AMNH paleontologists turned to other specimens. The AMNH Brontosaurus also included various elements from specimens found at Como Bluff and Bone Cabin Quarry, Wyoming, as well as plaster casts made from the Yale Brontosaurus material and other bones already in the AMNH collections.

And, of course, there was a question of the head. No one had ever discovered a Brontosaurus skull articulated or even associated with the rest of the skeleton. (And Earl Douglass’ discovery at Dinosaur National Monument was still four years away.) A skull had to be specially designed for the AMNH mount, and the New York museum followed Yale’s lead.

While all the bones from Marsh’s original Brontosaurus specimen came from Quarry 10 at Como Bluff, there was no skull among the lot. Rather than let the dinosaur go decapitated, however, Marsh identified two skull portions from a more diverse bonebed nearby, known as Quarry 13, as belonging to Brontosaurus. The sections of upper and lower jaws were set with spoon-shaped teeth, and these are the skull portions which make up the head of the famous 1883 reconstruction of the dinosaur Marsh commissioned.

The Como Bluff jaws outlined what the front of the dinosaur’s jaws might have looked like and, assuming that Marsh was correct, indicated that the skull of Brontosaurus was very different from that of Diplodocus. Fortuitously, the same AMNH expeditions to Bone Cabin Quarry which turned up Brontosaurus parts also brought back a complete Camarasaurus skull. Prior to this discovery, no one knew exactly what the head of Camarasaurus looked like. The fact that it seemed to share the spoon-shaped teeth assigned to Brontosaurus meant that the skull was a good model for reconstructing the rest of the missing “thunder lizard” skull. As far as I’m aware, the paleontologists did not consider that the supposed Brontosaurus skull parts, found in a different quarry than Marsh’s original specimen, really belonged to Camarasaurus.

Of course, accumulating all the right bones is just the first step in preparing a mount. Today, huge dinosaur skeletons are the stars of many museums. In 1905, though, such an effort had never been attempted before, and the AMNH paleontologists were not entirely sure how the brontosaur bones should be articulated. Matthew, along with colleague Walter Granger, dissected lizards and crocodiles to investigate how their muscles attached to their limb bones, and used these distant modern analogs to give their Brontosaurus a slightly bow-legged posture.

Mounted an a raised platform, the AMNH Brontosaurus looked like an impressive terrestrial titan. Yet during his study of the bones, Matthew concluded that Brontosaurus was a great amphibious dinosaur. Drawing from the authority of anatomist Richard Owen and paleontologist E.D. Cope, Matthew pointed out that the anatomy of Brontosaurus was so well-suited to life in water that you could tell the approximate depth at which the animal submerged. While the dense, heavy limbs of the dinosaurs acted like the heavy boots of deep-sea divers, Matthew pointed out, the sauropod’s light vertebral column would have been more buoyant. The dinosaur’s back therefore represented a sort of high water line which indicated the depth at which Brontosaurus wallowed in swamps, arcing its long neck to slurp up soft water plants.

Brontosaurus, in Matthew’s estimation, spent life slogging through a warm Jurassic bath. That seemed just as well—the dinosaur’s brain was comically small for its size. This sauropod was not an intelligent, behaviorally complex creature, Matthew argued, but a dim-witted leviathan devoted to a lazy lifestyle. “Hence we can best regard the Brontosaurus as a great, slow-moving animal automaton,” Matthew wrote, “a vast storehouse of organized matter directed chiefly or solely by instinct and to a very limited degree, if at all, by conscious intelligence.”

I am glad that dinosaurs have changed dramatically since Matthew characterized them as idiotic, clumsy piles of flesh. Apatosaurus and the whole rest of the dinosaurian ensemble are far more fascinating now than they were when bound to short and savage lives in steaming jungles and marshes. The true identity of “Brontosaurus” was eventually made clear, sauropods were ushered out of the swamps, butt-brains have been refuted, and paleontologists are able to extract more information about dinosaur lives from old bones than ever thought possible before.

And yet, I still feel some affection for Brontosaurus. This isn’t because I would prefer to see dumb, blunt-headed dinosaurs sloshing through algae-filled ponds, but because the old thunder lizard represented the epitome of true dinosaur-ness when I was a child. The mountain of muscle and bone was a wonderful icon which, in memory, reminds me just how much dinosaurs have changed during the twenty four years since I first saw the sauropod’s bones. I am thrilled that paleontologists sunk Brontosaurus, and the story of the icon’s demise reflects how paleontology has matured from a contest to see who could collect the biggest skeletons to a discipline that is carefully teasing out the secrets of prehistoric lives.

References:

Matthew, W.D. 1905. The mounted skeleton of Brontosaurus. American Museum Journal.V (2), 63-70

Osborn, H.F. 1906. The skeleton of Brontosaurus and the skull of Morosaurus. Nature. 1890 (73), 282-284

Parsons, K. 2001. Drawing Out Leviathan: Dinosaurs and the Science Wars. Bloomington: Indiana University Press. pp.1-21