Pisanosaurus is a small, herbivorous dinosaur that lived during the Late Triassic period, around 230 million years ago. It was discovered in what is now Argentina and is considered one of the earliest known members of the group called ornithischians, which includes many well-known dinosaurs like Stegosaurus and Triceratops. This dinosaur was characterized by its bipedal stance, meaning it walked on two legs, and had a beak-like mouth adapted for eating plants. Pisanosaurus is significant for understanding the early evolution of dinosaurs and their diverse adaptations in prehistoric ecosystems.