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Diggin' For Dinosaurs - National Museum of Natural History, Part 2
Next to the roadkill, visitors can spot another example of an ancient injury. The right hip bone of an ornithopod called Camptosaurus has a large hole, caused by an injury that never completely healed during the animal's lifetime. Major leg muscles would have originated from the damaged bone, so the injury must have impaired this dinosaur's ability to move.
The second jewel of the collection lurks on the other side of the aisle from Camptosaurus. There, visitors can find a specimen of the late Jurassic species Ceratosaurus, a predatory dinosaur displayed nowhere else in the world. A theropod far more primitive than Allosaurus and Tyrannosaurus, Ceratosaurus had an unusual horn on its snout. The Smithsonian's specimen of this animal has both a skeleton and a skull.
Nearby, another prize hangs against the wall. It's a specimen of Corythosaurus, a duckbilled dinosaur with a large bony crest on its head, as though it had been given a haircut in the "mohawk" style. The resemblance may be more than superficial. Experts think Corythosaurus and other crested hadrosaurs used their odd-shaped head ornaments to attract attention, particularly from members of the opposite sex. Curators cherish this specimen because impressions of the animal's skin are preserved between some of the tail vertebrae, something rarely seen with dinosaur fossils. Known as "the mummy," this fossil shows that Corythosaurus had skin with a scaly, pebbly texture.
The specimen of Triceratops next to Corythosaurus is a patchwork affair, composed of bones from many individuals. It harbors a secret mistake. When Charles W. Gilmore mounted the skeleton in 1905, he used the hind feet from a hadrosaur - like putting a pig's foot on the skeleton of a bull. Even if it had the right feet, the skeleton would still look a little funny by today's standards. The fossil was mounted at a time when palaeontologists thought Triceratops had sprawling limbs, like those of a crocodile. Researchers now believe that this dinosaur, as well as most others, stood on erect limbs, rather like an elephant or rhinoceros.
Other outdated ideas show up in the giant Diplodocus, an 87-foot-long specimen put on display in 1931. Like most sauropods, Diplodocus was built like a suspension bridge, with a long neck and tail extending horizontally from its central trunk and pillar-shaped legs. The Smithsonian version has its tail draped on the ground, but researchers now think that pose is incorrect. Diplodocus wouldn't have dragged its tail. If you're a dinosaur, especially in a herd, and you drag your tail, you've got a broken tail. In fact, the anatomy of the tail suggests that it went straight back.
Smithsonian curators are currently redesigning some of the mounts. Visitors can sometimes watch as the skeletons are taken apart and reconfigured.
Dinosaur cognoscenti may find some of the exhibit text a bit stale. The Smithsonian last renovated the hall in the early 1980s, and the explanatory panels hail from that era. But the dated descriptions don't subtract too much from the grandeur of these celebrated fossils, residents of an ancient world that transcend all time.