Pisanosaurus

Pisanosaurus (Pisano's Lizard) 1m Long

South America: Argentina

Late Triassic (228-216 MYA)

Herbivore 

Ornithischia

'''Pisanosaurus was the first fleet-footed herbivorous dinosaur to have ever existed and that the strange long teeth on it's bottom jaw might have supported a theory that it is related to another ornithischia dinosaur known as Heterodontosaurus that existed in Africa during the Early Jurassic period. It might been the prey item for the early carnivorous dinosaurs like Herrerasaurus and other predatory dinosaurs and may have proven difficult to catch for it would have been fast, agile and if it was caught the hunter would still have to deal with those sharp teeth that it had for defence. Pisanosaurus was more than likely the muntjacs of the prehistoric times for they would have likely spent their time alone for social groupings may have not have occurred just yet with the ornithischia.'''

This small dinosaur might have coexisted with other fellow plant eating dinosaurs like Mussaurus or Riojasaurus which might have offered them protection and as a distraction for carnivorous dinosaurs and other large reptiles that would have roamed the land during that time like Saurosuchus.