Jacksonia is an extinct mammal that lived in China during the Late Jurassic period. They were the largest mammals of the Mesozoic, about the size of a black bear. Despite this, it was a herbivore that likely fed on leaves, shrubs, cycads, ferns, and horsetails that lived during its time. They filled a similar niche to hadrosaurs and iguanodonts of the later times, living alongside Shunosaurus, Gasosaurus (its main predator), Sinraptor (its main predator), early stegosaurs, mamenchisaurus, guanlongs, Jurassic pterosaurs, and some others. The Jacksonia resembled a grizzly bear (without blubber), but with herbivore diet and teeth, wolverine-like tail, and rat-like ears.