Chungkingosaurus

Phylogeny: Dinosauria > Ornithischia > Genasauria > Thyreophora > Thyreophoroidea > Eurypoda > Stegosauria > Huayangosauridae

Overview: Chungkingosaurus was a fairly basal stegosaur, often classified as a close relative of an earlier genus called Huayangosaurus. Both dinosaurs are also often grouped together within a family called the Huayangosauridae, which contained many of the most “primitive” of the stegosaurs yet described. Most of the proposed huayangosaurids, like Chungkingosaurus and Huayangosaurus, are known from China. Chungkingosaurus, like its close relatives, wasn’t nearly as large as some of the more derived stegosaurs like Stegosaurus or Hesperosaurus (classified in the Stegosauridae). It was about four or so meters long, so around the same size as Huayangosaurus. Both dinosaurs sported more robust forelimbs and deeper skulls than those of the stegosaurids. They did differ, however, in a few key ways. While the jaws of Huayangosaurus still retained teeth towards the very front, Chungkingosaurus had lost those teeth, which is common among more derived stegosaurs. Both likely had similar lifestyles, as low-browsing herbivores feeding on ferns and cycads.

Stegosaurs in general are famed for their striking dermal armor, formed out of osteoderms (bones in the skin) that grew in twin rows along the neck, back, and tail. Chungkingosaurus appears to have had narrow, triangular plates along its back and four to six spines on its thagomizer – the array of spikes at the end of a stegosaur’s tail. The latter were probably used for defense or between males when competing for territory or mates, while the former were probably mainly display structures. Other known fossils from Chungkingosaurus include vertebrae, limb bones and part of the pelvis. Chungkingosaurus was first discovered in the 1970’s, near the city of Chongqing, then still a part of Sichuan. Described in 1983, the genus was named in honor of Chongqing, though using a different form of transliteration. Its fossils come from the upper layers of the Shaximiao Formation, while its relative Huayangosaurus comes from deeper within the Shaximiao. Chungkingosaurus may’ve lived alongside dinosaurs such as Tuojiangosaurus, Mamenchisaurus and the fearsome Yangchuanosaurus.