The oldest known dinosaurs lived in what's now South America during the late Triassic Period, some 231 million years ago. This group incorporated early versions of two-legged predators known as therapies.
But a big gap in the relic record just after this time led many experts to advise that these early dinosaurs had simply died out.
"The idea," Moon said, "was that there was this early diversification of dinosaurs ... but then they went extinct, and more superior predators took over during the late Triassic and diversified later at the Triassic-Jurassic boundary, when we know that dinosaur predators actually diversified and bigger a lot in size."
"Our new dinosaur, along with another one that was found a few years ago ... at the same site, indicates that those basal dinosaurs before now included a number of early theropods, and that they survived all the way through the Triassic to nearly the beginning of the Jurassic Period."