Simplify the following text for a Grade 10 native English-speaking person.
Original: Pisanosaurus mertii was described by Argentine paleontologist Rodolfo Casamiquela in 1967 .
Simplified: It was a bipedal herbivore described by Argentine paleontologist Rodolfo Casamiquela in 1967 . Only one species the type , Pisanosaurus mertii , is known , based on a single partial skeleton .