Apatosaurus

Apatosaurus was a massive, powerfully built diplodocid sauropod that roamed North America during the Late Jurassic period, between 155 and 148 million years ago. Measuring around 22 metres in length and weighing over twenty tonnes, it had an immense rib cage and very stout limbs compared to the gracile Diplodocus. Its neck was particularly remarkable, lined with heavily built cervical ribs that suggest powerful musculature, possibly used in intraspecific neck-shoving matches. At the rear, its whip-like tail could be lashed at high speeds for defence against predators like Allosaurus. Apatosaurus grazed widely across river plains, sweeping low vegetation into its mouth using simple peg-shaped teeth.

Its neck vertebrae possessed massive downward-directed ribs, giving it an exceptionally thick, muscular neck.

Where and when

Apatosaurus lived in the Late Jurassic, from 155 to 148 million years ago (Kimmeridgian-Tithonian age). Its remains come from United States, in the Morrison Formation.

The numbers

Length 22 m (estimates run from 21 to 23 m). Mass about 21 t. Hip height about 4.5 m. That is 12.9 human-lengths, or 1.96 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

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