The recapitation of Brontosaurus

With the discoveries of dinosaurs in the Western Interior of the USA during the late nineteenth century, box-car-loads of brand-new, but often incomplete, sauropod skeletons were shipped back east to places such as New Haven and Philadelphia. It was Yale's O. C. Marsh who described one ofthese new sauropods as Apatosaurus in 1877. With further shipments of specimens and more studies, Marsh again named a "new" sauropod in 1879 - Brontosaurus.

Years went by and - thanks to the burgeoning popularity of many kinds of dinosaurs - the public came to know the name Brontosaurus much better than it did the earlier-discovered Apatosaurus. Nevertheless, there was the suspicion by many sauropod researchers that Apatosaurus and Brontosaurus were the same kind of sauropod. In fact, this case was made in 1903 by E. S. Riggs, ofthe University ofKansas. Since then, most sauropod workers have regarded Brontosaurus as synonymous with Apatosaurus. If Apatosaurus and Brontosaurus are two names for the same sauropod, the older name, Apatosaurus, should be applied to this Late Jurassic giant.

But the more interesting story is not in the names, but in the heads. Again we go back to O. C. Marsh. Lamenting in 1883 that his material of "Brontosaurus" (now Apatosaurus) had no head, he made his best guess as to the kind of skull this animal had: one like Camarasaurus. And it was thus that Apatosaurus donned the short-snouted profile of its Morrison Formation cohort.

Enter H. F. Osborn, curator ofvertebrate paleontology and powerbroker ofthe American Museum of Natural History in New York, and W. J. Holland, curator of fossil vertebrates at the Carnegie Museum of Natural History in Pittsburgh and equally stalwart in his pursuit of "getting it right" about sauropods. Contemporary dinosaur researchers in the early part of the twentieth century, these two skirmished over the issue ofwhose head should reside on the neck of Apatosaurus. Osborn followed Marsh and had his mount ofthis majestic sauropod topped with a camarasaur head (Figure B8.2.1a), while Holland was strongly persuaded that Apatosaurus had a more Diplodocus-like head (based on a somewhat removed yet associated skull found near an otherwise quite complete skeleton at what is now Dinosaur National Monument in Colorado). But Holland gained no adherents and his mount of Apatosaurus in the Carnegie Museum remained headless in defiance of Osborn's dogma. After Holland's death, however, the skeleton was fitted with a camarasaur skull, almost as if commanded by Osborn himself.

Whose head belongs to whom was finally resolved in 1978 by Carnegie Museum Curator of Paleontology D. S. Berman and sauropod authority J. S. McIntosh. Through some fascinating detective work on the collection of sauropod specimens at the Carnegie Museum, these two researchers were able to establish that Apatosaurus had a rather Diplodocus-like skull - long and sleek, not blunt and stout as had previously been suggested. As a consequence, a number ofmuseums that display Apatosaurus skeletons celebrated the work ofBerman and McIntosh (and Holland) by conducting a painless head transplant - the first ever in dinosaurian history (Figure B8.2.1b).

Figure B8.2.1. (a) "Brontosaurus" on display at the American Musuem of Natural History in the early 1970s. This dinosaur was a chimera with a camarasaur head on an Apatosaurus body. (b) Apatosaurus being readied for display at the American Museum of Natural History in the mid 1990s.
Early Skeleton Brontosaurus

Sauropodomorphs were the largest terrestrial life forms of their times and indeed of all time. We often think of Brachiosaurus, from the Late Jurassic of the western USA, as well as from Tanzania (see Figure 8.14), which captured several decades' worth of people's imaginations as the largest land-living animal of all time (measuring 23 m long and

Figure 8.22. The skeleton of

Camarasaurus.

Figure 8.25. The diplodocoid sauropod Amargosaurus, from the Early Cretaceous of Argentina.
Figure 8.26. Osteoderms reconstructed along the back ofthe Late Jurassic North American diplodocoid, Diplodocus.

weighing in excess of 50,000 to 60,000 kg). Now supplanted by the likes of Argentinasaurus and Seismosaurus, Brachiosaurus nevertheless is still by far the best known of all of these earthly giants.

Yet sauropod evolutionary history is not entirely one of getting bigger. In Transylvania is found the sauropod Magyarosaurus, a creature 5-6 m in length, much smaller than contemporary sauropods elsewhere in the world. These smaller forms were dwarfs living on islands, a common phenomenon in the Mesozoic as now.

Sauropods were the fast-growing, yet slow-paced high-browsing giants of the Mesozoic. Today we view them as evolutionary marvels, as they continue to baffle, surprise, and inspire with biomechanical and evolutionary consequences of "living large."

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