Paleontologists in Argentina have announced the discovery of a major Jurassic-era fossil site four years after it was first discovered.

The site, which spans 23,000 square miles (60,000 square kilometers) in Patagonia, southern Argentina, came to light this week with the publication of a report in the journal Ameghiniana.

"No other place in the world contains the same amount and diversity of Jurassic fossils," said geologist Juan Garcia Massini of the Regional Center for Scientific Research and Technology Transfer (CRILAR).

The fossils -- between 140 and 160 million years old -- lie on the surface because they were recently exposed by erosion, said Garcia Massini, who leads the research team investigating the site.

"You can see the landscape as it appeared in the Jurassic -- how thermal waters, lakes and streams as well as plants and other parts of the ecosystem were distributed," he said.

The fossils were preserved almost immediately, in less than a day in some cases.

"You can see how fungi, cyanobacteria and worms moved when they were alive," Garcia Massini said of the site that lies along the Deseado Massif mountain range.

Ignacio Escapa of the Egidio Feruglio Paleontology Museum said the researchers had found "a wide range of micro and macro-organisms."

The fossils are so well preserved, that researchers say each rock extracted from the site could possibly open the door to a new discovery.