Scientists say that these ancient reptiles preyed mostly on mollusks like snails and clams, unlike the modern-day crocodilians.
Also, some of these crocodile species looked slightly different than the ones we have today, with rounder teeth and flatter snouts.
Because there was plenty of food for everyone, the crocodile species managed to live together in the same place without fighting over meals.
Paleontologists published the recent findings in the journal Proceedings of the Royal Society B.
John Flynn, a researcher at the American Museum of Natural History in New York and one of the scientists involved in the study, said that although the Amazon River basin is one of the most biologically diverse regions in the world, this biodiversity is still very poorly understood.
Due to the fact that the Amazon basin is mostly a vast rain forest, the scientists have little access to the fossils preserved by rocks.
However, the researchers were able to identify an area where there are plenty of fossil beds that hide many new and strange ancient species. Many of these species are unexpected, scientists claim.
The Amazon River formed approximately 10.5 million years ago, and before its formation, the region was made of a massive system of wetlands.
These regions were mostly made of swamps, lakes and rivers that drained toward what is now known as the Caribbean.
Flynn has been leading expeditions to the Amazonian River since 2002 and has discovered several new species of ancient animals.
The researchers discovered three new species of crocodiles, including Gnatusuchus pebasensis, a species of caiman with a short snout and round teeth.
The experts believe this crocodile species used its snout to dig through the mud, looking for clams and other mollusks.
Another species of crocodile the researchers discovered is the Paleosuchus caiman, which had a longer snout which the animal used for catching prey like fish and other aquatic creatures.
Rodolfo Salas-Gismondi, one of the lead authors of the study explained:
“We uncovered this special moment in time when the ancient megawetland 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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