Prehistoric Crocodile Paradise Dicovered In Peru

Crocodiles ruled the swampy ecosystem of what is now north-eastern Peru 13 million years ago, scientists have discovered. As many as seven different species of crocodile hunted in the lakes, swamps and rivers of the massive wetland region that pre-dated the Amazon basin. Knowing what kind of life existed there is crucial to understanding the origins of modern Amazonian diversity. But although invertebrates such as mollusks and crustaceans are common in Amazonian fossil deposits, evidence of vertebrates other than fish is very rare. The crocodile fossils were uncovered from a rock layer known as the Pebas Formation in north-eastern Peru in a series of excavations conducted since 2002.

Three of the species, described in the journal Proceedings of the Royal Society B, are entirely new to science. The most unusual is Gnatusuchus pebasensis, a short-faced caiman with globular teeth which is thought to have used its snout as a shovel to dig for clams and other mollusks. Gnatusuchus and other clam crunching crocs disappeared as the mega wetlands transformed into the modern Amazon and mollusk numbers and diversity declined. Researcher Rodolfo Salas-Gismondi, from the University of Montpellier in France said that when Gnatusuchus bones were analysed and researchers realised that it was probably a head-burrowing and shovelling caiman preying on mollusks living in muddy river and swamp bottoms, they knew it was a milestone for understanding proto-Amazonian wetland feeding dynamics.

The team also found the first clear fossil representative of modern smooth-fronted caimans which was adapted to catching a variety of prey including fish. The reasearchers 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. 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. Today, six caiman species live in the whole Amazon basin but only three ever co-exist in the same area and they rarely share the same habitat.

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