Period: Late Jurassic
Order, Suborder, Family: Ornithischia, Thyreophora, Stegosauridae
Location: Asia (People's Republic of China)
Length: 20 feet (6 meters)
The banks of a quiet, slow-moving Late Jurassic stream are lined with low, fernlike vegetation, and tall araucaria trees are in the background. A flock of leathery-winged, loud pterosaurs flaps by. The distant sound of ponderous footsteps gets closer. A bulky, rhino-size beast with a brightly colored zigzag of plates and spikes along its back and tail comes into view. Every few seconds it pauses to snip off a succulent cycad or a low fern with its horny beak, then moves on, mashing other plants underfoot. Its head is close to the ground where the thickest vegetation grows. For such a huge body, about 2,500 pounds, it had a small head. Its back curved up over hips higher than a man is tall. Many narrow paired triangular plates exaggerated the animal's arching profile. At the end of its tail were four sharp spines.
The slow-moving, peaceful life of Tuojiangosaurus was sometimes interrupted by battles with predators such as Yangchuanosaurus and Szechuanosaurus. It would also battle with another male Tuojiangosaurus for females.
Stegosaurs such as Tuojiangosaurus may not have had bony spikes and plates when they hatched. The armor may have developed slowly, growing fastest as the animal reached maturity. Different genera and species probably had different arrangements of plates and spines. This may have helped animals from the same species recognize each other.
Tuojiangosaurus multispinus probably had 17 pairs of thick, narrow, pointed plates. The last two pairs were thin cone-shaped spines at the end of its tail. The plates were low and bulbous on the neck and grew taller along the back toward the hips, then became shorter down the tail. There was also a large, platelike spine above each shoulder.
The fossils of two Tuojiangosaurus animals were found in the mid-1970s from the Wujiaba Quarry in the Shangshaximiao Formation near the Tuojiang, a river in the Sichuan Basin. One animal, the first almost complete stegosaur skeleton found in China, was mounted there in early 1977. The other specimen was only a set of five vertebrae. The skeleton of a third animal was discovered later but has not yet been prepared.
Plant-eating dinosaurs that lived at the same time as Tuojiangosaurus included its cousin stegosaurs Chialingosaurus and Chungkingosaurus, the sauropods Omeisaurus and Mamenchisaurus, and the small ornithopods Gongbusaurus and Yandusaurus.