Gigantspinosaurus
| Key | Value |
|---|---|
| Name Meaning | “giant-spined lizard” |
| Location | China (Sichuan) |
| Time Period | c. 160 million years ago (Late Jurassic) |
| Length | 14 ft (4.2 m) |
| Weight | 1,500 lb (700 kg) |
| Locomotion | Quadruped |
| Diet | Herbivore |
| Described | 1992 (Ouyang) |
| Geological Formation(s) | Shaximiao |
| Valid Species | Gigantspinosaurus sichuanensis (type) |
Phylogeny: Dinosauria > Ornithischia > Genasauria > Thyreophora > Thyreophoroidea > Eurypoda > Stegosauria > Huayangosauridae (?)
Overview: In most aspects, Gigantspinosaurus was a fairly typical stegosaur, possessing a tiny head, a sturdy body on four legs, rows of plates running down its back, and a spiked tail. What set it apart, however, was its shoulder spines. Shoulder spines in and of themselves weren’t unique among the Stegosauria, with many genera possessing them. Those of this dinosaur, however, stand out due to their enormous size. Said spines could measure up to a meter in length on a main body that grew to be maybe four or so meters long. They were robust, pointed and curved backwards. Described in 1992, Gigantspinosaurus was obviously named for its shoulder spikes. There were a handful of other stegosaurs with similarly huge spines, but this genus was the first known to have had such an exaggerated set. These spines were probably used either for defensive or courtship purposes. The plates on its back were generally unremarkable, being fairly small and narrow in form.
While shoulder spikes appear among a few different proposed stegosaurian lineages, the trait has often been seen as fairly “primitive”. The classification of Gigantspinosaurus itself has been hard to determine. It’s generally accepted as a basal stegosaur, often seen as more derived than genera like Huayangosaurus or Chungkingosaurus, which belonged to the family Huayangosauridae. There are some studies, however, that classify Gigantspinosaurus itself as a huayangosaurid. Fossils of the genus come from the upper layers of the Shaximiao Formation, in the Sichuan Province of China. It was at first mistaken for Tuojiangosaurus, though its shoulder spines quickly proved it was distinct. The two stegosaurs may’ve coexisted, perhaps occupying slightly different niches. Other dinosaurs in the region at that time included the large sauropod Mamenchisaurus and Yangchuanosaurus – a large metriacanthosaurid allosauroid and likely the top predator of the Shaximiao environment.