Pisanosaurus is one of the oldest known herbivorous - or plant-eating - dinosaurs. It lived about 220 million years ago. Being such a primitive dinosaur, Pisanosaurus did not look very different from early carnivores, or meat-eating dinosaurs. They were all closely related at the time. Like the meat-eaters, Pisanosaurus walked on two legs. Itwas a small dinosaur. Plant-eaters grew bigger much later in the Triassic period. Then they began to walk on four legs instead of two to carry their heavy bodies.
Little is known about this small dinosaur. Only bits and pieces of its skeleton have been found. It had closely-packed pointy teeth that were all about the same size. It probably ate plants. Since it was a very simple dinosaur, it did not have a well-developed stomach. For this reason, Pisanosaurus probably stayed away from the tougher plants and ate ferns and softer leaves instead.
Pisanosaurus was about three feet long and one foot high. It weighed about 15 pounds, about the size of a small turkey. It had long, narrow feet and was probably a fast runner. We learn about a dinosaur’s speed by studying their trackways, or footprints they leave behind. If the prints are far apart, then we know that the dinosaur took big steps when it walked. Prints that are close together mean that the dinosaur walked slowly. Pisanosaurus was found in what is now Africa and Argentina.