SCIENCE

Bonanza Of Ancient Crocodiles Unearthed In The Peruvian Amazon

02/25/2015 01:40 pm ET | Updated Feb 25, 2015
© Javier Herbozo

Talk about a crocodile paradise.

Scientists examining fossil outcrops in northeastern Peru near the city of Iquitos were stunned to discover the fossils of not one, but seven different species of ancient crocs--three of which are newly identified--that lived in the region 13 million years ago.

They're saying it's the largest number of crocodile species that have ever lived side by side in one habitat throughout Earth's history. The discovery offers new insights into what the region's ecosystem was like before the Amazon River formed around 10.5 million years ago.

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crocodile fossils
Fossils from seven different species of crocodiles uncovered in what is now the Amazon Basin of northeastern Peru. Their skulls and jaws, shown here, are extremely diverse: (1) Gnatusuchus pebasensis, (2) Kuttanacaiman iquitosensis, (3) Caiman wannlangstoni, (4) Purussaurus neivensis, (5) Mourasuchus atopus, (6) Pebas Paleosuchus, and (7) Pebas gavialoid. The three new species (1-3) are shown in illustrations below the respective fossils.

"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," Rodolfo Salas-Gismondi, lead researcher and chief of the paleontology department at the National University of San Marcos' Museum of Natural History in Lima, Peru, said in a written statement.

The wetlands supported a variety of food sources that could sustain such a diverse group of crocs, according to the researchers. One of the weirdest newfound crocs, dubbed Gnatusuchus pebasensis, had rounded teeth and a strange shovel-like snout, which it used to snag clams and other mollusks. Other species, like Paleosuchus, had longer snouts that allowed them to catch swimming prey like fish.

ancient crocodile
This model is a life reconstruction of the head of Gnatusuchus pebasensis, a 13-million-year-old, short-faced crocodile with globular teeth that was thought to use its snout to "shovel" mud bottoms, digging for clams and other mollusks.

What caused the downfall of this diverse crocodile group? The formation of the Amazon river system drove down mollusk populations, causing species like Gnatusuchus to go extinct, while crocs with a more generalized diet survived, according to the researchers.

Today, the Amazon's croc population is much less diverse. Out of the six crocodile species that live in the Amazon basin, only three co-exist in the same area.

The new fossil findings were published online on Feb. 25 in the journal Proceedings of the Royal Society B.

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