Diplodocus

Phylogeny: Dinosauria > Saurischia > Sauropodomorpha > Plateosauria > Massopoda > Sauropodiformes > Sauropoda > Gravisauria > Eusauropoda > Neosauropoda > Diplodocoidea > Diplodocidae > Diplodocinae

Overview: In the 1870’s, the bitter rivalry between American paleontologists Othniel C. Marsh and Edward D. Cope, also known as the “Bone Wars”, was heating up. The two scientists sent teams of fossil hunters into the western United States in search of fossils. In the end, Marsh would describe and name considerably more still valid taxa, Diplodocus among them. Fossils of this sauropod were first unearthed in 1877, with a description of the find coming the following year. The generic name of Diplodocus means “double-beamed”, referring to the chevron bones on the bottom surface of its tail vertebrae. These were double-pronged in form, which at the time was new to Marsh, but in later decades, other sauropods were found with such chevrons. Marsh’s type species, Diplodocus longus, is often seen as dubious today, since it’s based on fairly limited remains. However, a large number of Diplodocus fossils would later be found, including those of other species, most notably Diplodocus carnegii, based on far more complete fossils. Said species, described in 1901, honors the industrialist Andrew Carnegie, who sponsored numerous paleontological expeditions.

With the large number of Diplodocus specimens known, it’s little wonder it would go onto become one of the more well known sauropods to the general public. Numerous mounted skeletons can be found in museums, many of them sent out across the world by Carnegie himself. Its basic anatomy and appearance are well understood. Diplodocus was a long and slender-built sauropod, sporting both an elongated neck and tail. The distal end of the tail grew narrow, like a whip, which some see as a potential weapon to lash out at attacking predators. No skull material has been found, but we have skulls from its close relatives. Its skull was probably relatively small with a narrow snout, the jaws tipped with elongated, pencil-like teeth. Such teeth were better suited for stripping branches of leaves and needles than they were for chewing. Food was mainly processed in the gut, largely by swallowed stones, or gastrolithes. How it held its neck has been debated. Some studies suggest its neck was held mostly out straight from the shoulders, but others find it would’ve held its neck up fairly high.

Diplodocus averaged around twenty-five to twenty-six meters long as an adult. For a long time, the genus was cited as the longest known dinosaur. One species, Diplodocus hallorum, reached lengths of over thirty meters. In the 1990’s, fossils of D. hallorum were used as the basis for a genus called Seismosaurus, but it was later recognized as a junior synonym of Diplodocus. Even with its great potential length, however, Diplodocus was surprisingly lightly built. It was only a fraction of the weight of similarly-long sauropods due to its gracile build. Many of its relatives were also similar, with Diplodocus acting as the namesake of its family – the Diplodocidae. Diplodocids particularly close to it were in the subfamily Diplodocinae, like Barosaurus and Supersaurus, while genera like Apatosaurus and its relative Brontosaurus belonged to the more distantly related subfamily Apatosaurinae (which were usually slightly bulkier animals). Diplodocus is known from the Morrison Formation, dating it to the Late Jurassic. It lived in a semi-arid, seasonal environment feeding on conifers and similar trees. In this same region were famous dinosaurs like Brachiosaurus, Stegosaurus and Allosaurus.