Spinophorosaurus

Spinophorosaurus was an early, long-necked sauropod that lived in what is now Niger during the Middle Jurassic period. Reaching an estimated length of thirteen to fourteen metres and weighing around seven tonnes, it was roughly the mass of a large African elephant. The discovery of Spinophorosaurus is famous for a notable anatomical mix-up. When first described, palaeontologists interpreted two pointed bones found near the tail as a defensive thagomizer of tail spikes, similar to those of a stegosaur. Later investigations showed that these elements were actually misplaced clavicles from the shoulder girdle. Despite losing its tail spikes, Spinophorosaurus remains crucial for understanding sauropod evolution. It possesses exceptionally complete cranial and neck material, and computed tomography scans of its braincase reveal well-developed inner ear canals that helped it coordinate complex neck movements while browsing high in the Jurassic forest canopy.

Spikes originally thought to be a tail weapon turned out to be clavicles from the shoulder girdle.

Where and when

Spinophorosaurus lived in the Middle Jurassic, from 170.3 to 163.5 million years ago (Bajocian-Bathonian age). Its remains come from Niger, in the Tiourarén Formation.

The numbers

Length 14 m (estimates run from 13 to 14 m). Mass about 7.1 t. Hip height about 3.5 m. That is 7.9 human-lengths, or 1.21 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

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