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'Clam-Crunching' Prehistoric Crocs Ruled Amazon

'Clam-Crunching' Prehistoric Crocs Ruled Amazon

Scientists have discovered that at least seven different species of crocodile dominated the swampy regions of northeastern Peru millions of years ago.

Crocodile fossils have been unearthed in a series of excavations which began in 2002, leading to the discovery of three new species.

The reptiles hunted in the lakes, swamps and rivers of the wetlands that pre-date the Amazon basin, according to the findings of a study in the journal Proceedings of the Royal Society B.

Finding fossils of invertebrates such as molluscs and crustaceans is common in the Amazon, but evidence of vertebrates other than fish is rare.

Experts say the find could help shed light on the origins and diversity of the Amazon as it exists today.

The most unusual of the new discoveries is a short-faced caiman with globular teeth, called Gnatusuchus Pebasensis, which is thought have used its snout as a shovel to dig for clams and other molluscs.

Gnatusuchus and other "clam-crunching" crocs disappeared as the wetlands transformed into the modern Amazon and the number of molluscs declined.

Researchers also found the first, clear fossil representative of the modern smooth-fronted caimans which adapted to catching a variety of prey including fish.

"We uncovered this special moment in time when the ancient mega-wetland ecosystem reached its peak in size and complexity, just before its demise and the start of the modern Amazon River system," researcher Rodolfo Salas-Gismondi, from the University of Montpellier in France, said.

"At this moment, most known caiman groups co-existed: ancient lineages bearing unusual blunt snouts and globular teeth along with those more generalised feeders representing the beginning of what was to come."

Six caiman species live in the Amazon basin today, but only three ever coexist in the same area and they rarely share the same habitat.