Haplocanthosaurus

Haplocanthosaurus was an unusual sauropod dinosaur from the Late Jurassic of North America, living approximately 152 million years ago. It inhabited the sprawling floodplains of the Morrison Formation alongside more famous giants like Diplodocus and Brachiosaurus. Measuring between 14 and 20 metres in length, it was modest in scale for a sauropod. Its name refers to the distinctive simple neural spines along its backbone, which lacked the forked structure common in other diplodocoids. Its evolutionary position remains debated, with palaeontologists placing it either as an exceptionally primitive diplodocoid or a very basal member of the macronarian branch. It probably spent its days browsing on ferns, horsetails, and cycads.

Unlike many contemporaries, its vertebrae lacked split or forked neural spines, retaining a simple solid form.

Where and when

Haplocanthosaurus 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 17 m (estimates run from 14 to 20 m). Mass about 13 t. Hip height about 3.5 m. That is 10 human-lengths, or 1.52 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

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