The discoveries of the fauna in the Valley of the Moon have been very important, especially in the last years.
The Proterochampsa, the complete skeleton of a Rincosaurio (it is the most complete and best conserved up to now, a relative of the lizards that lived on ferns), three Saurosuchus Galilei (5 meters long, carnivorous, considered the biggest of Ischigualasto), bones of a Poposuridae, a Herrerasaurus Ischigualastensis (ancestor of the dinosaurs and very similar to the Tiranosaurus Rex), a complete animal which resembles a crocodile), Scaphonyx Sanjuanesis, Promastodonsaurus Belmani (ancestor of the amphibians) and the Eoraptor Lunesis (considered to have an age of 225 million years and found in 1993). The scientist William Dudley Sill has said "Some day in Ischigualasto, the fossil of the most primitive mammal in the world will be discovered, here, in this valley, I sense, it has to be in this valley."