Diplodocus: the long-tailed giant of the Morrison Formation

When and where

Diplodocus lived in the Late Jurassic, between 154 and 152 million years ago, across the Morrison Formation of western North America. Its bones turn up in Wyoming, Colorado, Utah, and Montana, embedded in floodplain deposits laid down when the region was a low-lying basin of seasonal rivers and conifer forests. Diplodocus shared this landscape with Allosaurus, Stegosaurus, Brachiosaurus, and Apatosaurus, making the Morrison one of the richest single-formation dinosaur faunas ever found.

How we know

S. W. Williston unearthed the first Diplodocus bones in 1877, and Othniel Charles Marsh named the genus the following year. The species name comes from the Greek for "double beam," a reference to the paired chevron bones running under the tail. Andrew Carnegie funded the most famous specimen, "Dippy," excavated in Wyoming in 1899 and now displayed at the Carnegie Museum of Natural History in Pittsburgh. Carnegie also commissioned plaster casts of Dippy as gifts for museums in London, Berlin, Paris, Vienna, and beyond, which is why Diplodocus skeletons greet visitors in so many capital-city natural history halls. Source: Wikipedia entry on Diplodocus.

What set it apart

Diplodocus was built around its tail. The animal stretched to 26 metres long, but more than 13 metres of that was tail alone, ending in a long whip of 80-plus vertebrae. Bone-stress modelling published in the 2000s suggested the tip could crack the air at supersonic speed when swung, generating a defensive sonic snap. The neck held the same 80-plus vertebra count, balanced over the hips by the tail like a horizontal seesaw. Teeth lined only the front of the mouth, narrow and peg-shaped, used to rake leaves and ferns from low-growing vegetation rather than chew them. Diplodocus weighed roughly 10 to 15 tonnes, light for its length compared to the bulkier Brachiosaurus.

For collectors and classrooms

A scaled hand-painted Diplodocus figurine teaches the proportions better than any diagram. Look for one that puts the tail off the ground in a horizontal posture, not dragging behind it, since the dragged-tail pose was discarded by paleontologists in the 1970s. Browse a hand-painted figurine.