Scientists have found that it weren't the dinosaurs who ruled Earth 13 million years ago in Peru, it were the crocodiles.
There were at least 7 different species of the reptile that hunted in the lakes, swamps and rivers of the massive wetland region that pre-dated the Amazon basin, the Mirror reported.
Scientists uncovered the crocodile fossils from a rock layer known as the Pebas Formation in north-eastern Peru in a series of excavations conducted since 2002, of which 3 of the species are entirely new to science.
Gnatusuchus pebasensis, a short-faced caiman with "globular teeth" is the most unusual, which is believed to have used its snout as a shovel to dig for clams and other mollusks.
These species vanished when 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 they" 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."
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It's a milestone for understanding proto-Amazonian wetland feeding dynamics, he added.
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.
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.
The findings are described in the journal Proceedings of the Royal Society B.