The oldest dinosaur types are known from rocks in Argentina and Brazil that are about 230 million years old, and date from the Triassic period. One of the earliest known primitive dinosaurs was Eoraptor ("dawn hunter") a fast-running, one-metre long carnivore. Because Eoraptor's skeleton shows some advanced skeletal features, older dinosaurs may yet be found. After the evolution of such early types, dinosaurs evolved very quickly, becoming more and more diverse and reaching out into many of the ecological niches.