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Diadectes amercanum (name meaning "American crosswise-biter") is a species of large reptiliomorph that originally lived during the early Permian period (Artinskian-Kungurian stages of the Cisuralian epoch, between 290 and 272 million years ago) as an extinct species of Diadectes and was once extinct, but has since been brought back from extinction by SciiFii and now lives in Paleozoic Park located in Downey, California. As one of the first herbivorous tetrapods, Diadectes amercanum feeds mainly on leaves, fallen pine needles, fruits, cycads, ferns, and horsetails. As one of the first fully terrestrial animals to attain large size, growing on average of about 5 to 10 feet (1.5 to 3 meters) long and weigh about as much as a large sheep. It possesses some characteristics of reptilians and amphibians, combining a reptile-like skeleton with a more primitive, seymouriamorph-like head. The eight front teeth are spatulate and peg-like, and serve as incisors that are used to nip off mouthfuls of vegetation. The broad, blunt cheek teeth functions similarly to molars, grinding up the food. It also has a partial secondary palate, allowing it to chew its food and breathe at the same time, something many even more advanced reptiles are unable to do. These traits are adaptations related to the animals' high-fiber, herbivorous diet, and evolved independently of similar traits seen in some reptilian groups. It is a solitary animal that usually throughout almost its entire life alone except during the breeding seasons. Though it is fully terrestrial as an adult, Diadectes amercanum still has to lay eggs in the water, which are jellied like amphibian eggs, and the tadpoles emerge from the eggs to spend for 2-3 weeks until they grow up into fully-terrestrial juveniles. Although Diadectes amercanum is most well known in Paleozoic Park, there are expanding feral populations of Diadectes amercanum throughout California, Arizona, and Nevada, which are, by all accounts, thriving, and may be due to the people from illegal pet trades who deliberately released them to the wild. Diadectes amercanum are able to tolerate the arid climates and freezing temperatures, likely unlike the original species, due to genetic engineering to make them suitable for zoos/safari parks in case they wouldn't do well in captivity without being modified. Because of this, it is expected that the populations of Diadectes amercanum in the wild will continue to grow and expand into new territories.