Timackrosaurus

Timackrosaurus is an extinct species of Kentrosaur-sized Stegosaur that live in what is now Utah, Wyoming, Colorado, and South Dakota during the Late Jurassic and Early Cretaceous. It was unlike most other Stegosaurs in the fact that it was covered in armored plates instead of plates on its back, presumably for protection from newly evolving predators like Dromaeosaurs. It was a herbivore like most Stegosaurs and likely mainly fed on low-lying plants like ferns, cycads, and among other low-growing vegetation. It was most likely a solitary animal and only came with its own kind in order to breed. It is unknown why this species became extinct around 115 million years ago, despite being around around 45 million years (after first evolving around 160 million years ago), so Dromaeosaurs and Carcharodontosaurids weren't likely to have caused the extinction of Timackrosaurus, but new evidence suggests that Gastonia, an Ankylosaur witha similar niche, may have outcompeted Timackrosaurus to extinction.