On an arid plateau in the heart of Argentina's Patagonia, researchers have discovered a fossil deposit brimming with the remains of beasts that roamed the region millions of years ago, leading scientists to liken the site to Michael Crichton's fictional Jurassic Park. Indeed, the material they have retrieved thus faran estimated 2 percent of site's contentsincludes a number of previously unknown species. "What we have found is very important, firstly because of the range of fossils found, and secondly because of the age," Gerardo Cladera of the Egidio Feruglio Paleontology Museum in Trelew told Reuters.

Earlier exploration of this region, in the province of Chubut, had turned up the remains of two dinosaurs in the 1970s and '80s. But the area was abandoned until six months ago, when a local farmer came upon bones eroding out of the ground. Those turned out to be the backbone of a large herbivore. Subsequent investigation revealed four unknown species of dinosaurs, one of the oldest-known mammals, and various amphibians, turtles and pterodactyls. The new dinosaur species, which date to between 150 and 160 million years ago, include herbivorous sauropods stretching nearly 10 yards in length and carnivorous theropods. The mammal is said to be the size of a rat, though not itself a rodent.

Despite its diminutive stature, the mammal fossil may be the most important of the new finds. "It is the first mammal of that antiquity to be found in South America," paleontologist Jos Bonaparte of Argentina's National Museum of Natural Sciences told Inter Press Service, "and among the very few found anywhere in the world."