More fossil specimens of Diplodocus have been discovered than of just about any other sauropod, making this huge plant-eater one of the world's best-understood dinosaurs. Here are 10 facts you may or may not have known about Diplodocus. (See also a gallery of Diplodocus pictures.)
1. Most Diplodocus museum specimens are gifts from Andrew Carnegie.
Early in the 20th century, the wealthy steel baron Andrew Carnegie donated casts of complete Diplodocus skeletons to various European monarchs--the result being that you can see Diplodocus at a dozen museums worldwide, including London's Natural History Museum, the Museo de la Plata in Argentina, and, of course, the Carnegie Museum of Natural History in Pittsburgh (the last consisting of the original bones, not reproductions).
2. Seismosaurus may have been an unusually large species of Diplodocus.
As is the case with many dinosaurs, it can sometimes be hard to distinguish between genuinely new genera and species of existing sauropods. A case in point is the long-necked Seismosaurus ("earthquake lizard"), which some paleontologists believe should be classified as an unusually large species of Diplodocus, Diplodocus hallorum. (Wherever it winds up on the sauropod family tree, Seismosaurus was truly gigantic, measuring over 100 feet from head to tail and weighing 100 tons!)
3. Diplodocus wasn't the smartest dinosaur on the Jurassic block.
Sauropods like Diplodocus had almost comically tiny brains compared to the rest of their bodies. Extrapolating the IQ of a 150-million-year-old dinosaur can be tricky, but it's a sure bet that Diplodocus was only slightly smarter than the plants it feasted on (though if this sauropod roamed in herds, as some experts speculate, it may have been slightly smarter). Even still, it was probably smarter than the contemporary Stegosaurus, which had a brain the size of a walnut.
4. Diplodocus' neck and tail consisted of almost 100 vertebrae.
The greatest part of Diplodocus' length was taken up by its neck and tail, which differed slightly in structure: its long neck was scaffolded on about 15 elongated vertebrae, while its tail comprised about 80 vertebrae. This dense skeletal arrangement hints that Diplodocus may have used its tail not only as a counterbalance to its neck, but as a supple, whiplike weapon, though the evidence for this is far from conclusive.
5. The name Diplodocus means "double beam."
The paleontologists of the late 19th century weren't quite as creative as their modern counterparts. Diplodocus was named not for its enormous size, but for an obscure anatomical feature, the "double beamed" bones on the underside of its tail. (By the way, the correct pronunciation of this dinosaur is dip-LOW-doe-kuss, not dip-low-DOE-kuss, though even seasoned paleontologists sometimes prefer the latter)
6. Diplodocus may have held its long neck level to the ground.
Paleontologists have had a hard time reconciling the (presumed) cold-blooded metabolism of sauropods with the idea that they held their necks high up off the ground (which would place an enormous amount of stress on their hearts). Today, the weight of the evidence is that Diplodocus held its neck in a horizontal position, sweeping its head back and forth to feed on low-lying vegetation, though not everyone subscribes to this theory.
7. Diplodocus was probably a "branch stripper."
The odd shape and arrangement of Diplodocus' teeth, combined with the lateral flexibility of its neck, has led paleontologists to conclude that this sauropod was a "branch stripper"--that is, it seized low-lying branches with its weak jaws and methodically stripped them of leaves, without much (if any) chewing involved. Whatever the case, Diplodocus' metabolic requirements would have been truly massive, amounting to hundreds of pounds of food per day.
8. Estimates of Diplodocus' weight have been vastly exaggerated...
Despite its imposing reputation, Diplodocus was actually rather svelte compared to other sauropods, attaining a top weight of "only" 20 or 25 tons. However, it's possible that some superannuated individuals (or separate Diplodocus species) weighed more, in the neighborhood of 30 to 50 tons, and then there's the outlier of the group, the 100-ton Seismosaurus (the exact heft of which is still a matter of speculation).
9. ...but it's still the longest dinosaur that ever lived.
From the end of its snout to the tip of the tail, an adult Diplodocus could attain a length of over 175 feet. To put this number into perspective, a full-length school bus measures about 40 feet from front to back, and a regulation football field is 300 feet long. A full-grown Diplodocus would stretch from one goal line to the other team's 40-yard-marker, which presumably would make the game very difficult to play.
10. Diplodocus' front limbs were shorter than its hind limbs.
All sauropods were pretty much alike, except for the big differences. For example, the front legs of Brachiosaurus were significantly longer than its hind legs--and the exact opposite was true of Diplodocus. The low-slung posture of this sauropod lends weight to the theory that it browsed on low-lying vegetation rather than the tops of tall trees, though there might be another reason for this adaptation (perhaps having to do with the requirements of mating).