Facts About Diplodocus

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How Much Do You Know About Diplodocus?

Alain Beneteau.

Whether you pronounce it correctly (dip-LOW-doe-kuss) or incorrectly (DIP-low-DOE-kuss), Diplodocus was one of the biggest dinosaurs of late Jurassic North America--and 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. On the following slides, you'll discover 10 fascinating Diplodocus facts.

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Diplodocus Was the Longest Dinosaur that Ever Lived

Colin Keates / Getty Images

From the end of its snout to the tip of its 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 passing plays a risky proposition. (To be fair, though, most of this length was taken up by Diplodocus' enormously long neck and tail, not its bloated trunk.)

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Estimates of Diplodocus' Weight Have Been Vastly Exaggerated

Vladimir Nikolov.

Despite its imposing reputation--and its enormous length--Diplodocus was actually rather svelte compared to other sauropods of the late Jurassic period, attaining a maximum weight of "only" 20 or 25 tons, compared to over 50 tons for the contemporary Brachiosaurus. However, it's possible that some exceptionally elderly individuals weighed more, in the neighborhood of 30 to 50 tons, and there's also the outlier of the group, the 100-ton Seismosaurus, which may or may not have been a true Diplodocus species (see slide #9).

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Diplodocus' Front Limbs Were Shorter than its Hind Limbs

Dmitry Bogdanov.

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 the contemporary Diplodocus. The low-slung, ground-hugging posture of this sauropod lends weight to the theory that Diplodocus browsed on low-lying shrubs and bushes rather than the tops of tall trees, though there might be another reason for this adaptation (perhaps having to do with the tricky demands of Diplodocus sex, about which we know very little).

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The Neck and Tail of Diplodocus Consisted of Almost 100 Vertebrae

Some of Diplodocus' massive vertebrae (Wikimedia Commons).

As mentioned in slide #2, the greatest part of Diplodocus' length was taken up by its neck and tail, which differed slightly in structure: the long neck of this dinosaur was scaffolded on only 15 or so elongated vertebrae, while its tail was made up of 80 much shorter bones. This dense skeletal arrangement hints that Diplodocus may have used its tail not only as a counterbalance to the weight of its neck but as a supple, whiplike weapon to hold predators at bay, although the fossil evidence for this is far from conclusive.

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Most Diplodocus Museum Specimens Are Gifts from Andrew Carnegie

andrew carnegie
Andrew Carnegie (Wikimedia Commons).

Early in the 20th century, the wealthy steel baron Andrew Carnegie donated complete casts of Diplodocus skeletons to various European monarchs--the result being that you can view a life-sized Diplodocus at no less than 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 (this last exhibit consisting of the original bones, not plaster reproductions).  Diplodocus itself, by the way, was named not by Carnegie, but by the famous 19th-century paleontologist Othniel C. Marsh.

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Diplodocus Wasn't the Smartest Dinosaur on the Jurassic Block

Alain Beneteau.

Sauropods like Diplodocus possessed 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 munched on (though if this dinosaur roamed in herds, as some experts speculate, it may have been slightly smarter). Still, Diplodocus was a Jurassic Albert Einstein compared to the contemporary plant-eating dinosaur Stegosaurus, which only had a brain the size of a walnut. 

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Diplodocus Probably Held its Long Neck Level to the Ground

Wikimedia Commons.

Paleontologists have a hard time reconciling the (presumed) cold-blooded metabolism of sauropod dinosaurs with the idea that they held their necks high up off the ground (which would have placed an enormous amount of stress on their hearts--imagine having to pump blood 30 or 40 feet into the air!). 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--a theory supported by the odd shape and arrangement of Diplodocus' teeth and the lateral flexibility of its enormous neck, which was like the hose of an enormous vacuum cleaner.

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Diplodocus May Have Been the Same Dinosaur as Seismosaurus

Seismosaurus, also known as D. hallorum (Wikimedia Commons).

It can often be hard to distinguish between different genera, species, and individuals of 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, D. hallorum. Wherever it winds up on the sauropod family tree, Seismosaurus was a true giant, measuring over 100 feet from head to tail and weighing as much as 100 tons--putting it in the same weight class as the largest titanosaurs of the ensuing Cretaceous period.

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A Full-Grown Diplodocus Had no Natural Enemies

Wikimedia Commons

Given its enormous size, it's extremely unlikely that a healthy, full-grown, 25-ton Diplodocus would be targeted by predators--even if, say, the contemporary, one-ton Allosaurus was smart enough to hunt in packs. Rather, the theropod dinosaurs of late Jurassic North America would have targeted the eggs, hatchlings and juveniles of this sauropod (one imagines that very few newborn Diplodocus survived into adulthood), and would only have focused their attention on adults if they were sick or elderly, and thus more likely to lag behind a stampeding herd.

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Diplodocus Was Closely Related to Apatosaurus

Apatosaurus (Wikimedia Commons).

Paleontologists still haven't agreed on a definitive classification scheme for "brachiosaurid" sauropods (i.e., dinosaurs closely related to Brachiosaurus) and "diplodocoid" sauropods (i.e., dinosaurs closely related to Diplodocus). However, pretty much everyone agrees that Apatosaurus (the dinosaur formerly known as Brontosaurus) was a close relative of Diplodocus--both of these sauropods roamed western North America during the late Jurassic period--and the same may (or may not) apply to more obscure genera like Barosaurus and the colorfully named Suuwassea.