Tuojiangosaurus

Type Species: Tuojiangosaurus multispinus

Classification: Dinosauria – Ornithischia – Thyreophora – Stegosauria – Stegosauridae 

Time Period: Late Jurassic

Location: China

Diet: Herbivore 

The Chinese stegosaur Tuojiangosaurus was discovered in the Shaximiao Formation of China. This bone-bed dates back to the Oxfordian stage of the Late Jurassic, and this stegosaur is one of three stegosaurs found in the environment (the other two are Chialingosaurus and Chungkingosaurus). Contemporaries of Tuojiangosaurus included sauropods such as Mamenchisaurus and Shunosaurus, theropods such as Yangchuanosaurus and Gasosaurus, and ornithischians such as the early ornithopod Agilisaurus and a heterodontosaur holdout from the earlier Jurassic known as Tianyulong. 

Tuojiangosaurus is the best understood Chinese stegosaur. It was medium-sized at twenty-three long and six and a half feet tall. Its weight has been estimated to nearly three tons. It had a narrow and low head, bulky body, and short limbs. It had at least twenty-five teeth, and these teeth had a thick base that merged at the inside into a triangular vertical median ridge. Tuojiangosaurus had two rows of plates along its spine; these became taller over the hip region. Those at the neck and front trunk were rounded or pear-shaped, while the plates towards the rear became more triangular and pointed. All the plates had a thickened central section, as if they were modified spikes. Tuojiangosaurus seems to have had seventeen pairs of these plates and spikes. 

The thagomizer at the end of its tail consisted of two outward-pointing robust spikes on each end of the tail. These were angled at 45 degrees towards the vertical, indicating they were used for defensive purposes. The plates wouldn’t have been any protection against predators, as they’re too weak and brittle to protect against a powerful bite. Because they’re not adapted enough for thermoregulation purposes, it seems the best explanation towards their purpose is that of inter-species display. Many stegosaur species coexisted, and recognizing one’s own kind would’ve been aided by particular arrangements and shapes of plates between species. 

the shoulder spikes on this Tuojiangosaurus are hypothetical, based on the fact that
many primitive stegosaurs - and its contemporaries - had shoulder spikes. None were found
with the remains we have.