By Will Dunham
WASHINGTON (Reuters) - If one croc is reason enough to stay out of the water, how about dipping your toes in a place with seven different croc species including two 26-foot (8-meter) monsters, all living side by side eating just about anything that moves?
That is what life was like in the lush Peruvian Amazon basin 13 million years ago. It featured Earth's all-time croc bloc: the most crocodilian species dwelling in the same place and time in our planet's history, scientists said on Tuesday.
The scientists unearthed the croc remains in two small fossil bone beds near the northeastern Peruvian city of Iquitos.
One of the strangest was Gnatusuchus pebasensis, a 5-foot (1.6-meter) caiman with a shellfish fondness. Its shovel-like snout let it bury its head in muddy wetland bottoms and root around for prey. Its bulbous teeth were perfect for crushing shells of mollusks like clams.
"This highly specialized anatomy and lifestyle was previously unknown in any other crocodile," said paleontologist John Flynn of New York's American Museum of Natural History.
The discoveries are helping scientists better understand both the origins of modern Amazonian biodiversity and the ancient assortment of life before the Amazon River formed 10.5 million years ago. The region 13 million years ago boasted immense wetlands abounding with lakes, swamps and rivers.
"Regarding the Amazon, we are just grasping the surface of an extremely complex and fascinating history," said Rodolfo Salas-Gismondi, vertebrate paleontology chief at Lima's Natural History Museum also affiliated with France's University of Montpellier.
The researchers said seven croc species could coexist because they shared an elaborate environment with plenty of food and were not all chasing the same prey.
"This mega-wetlands system fostered unusually rich communities of aquatic prey species. Over time, crocodiles evolved a dazzling array of skull shapes, feeding adaptations and body sizes," Flynn said.
With powerful jaws and teeth, 26-foot Purussaurus neivensis was the neighborhood bully. Later Purussaurus species reached 43 feet (13 meters).
Mourasuchus atopus, also 26 feet, was a weird filter-feeder akin to a whale shark or baleen whale, using rows of small teeth to sift huge quantities of small prey.
There were two other clam-crunching caimans and a species of the existing caiman genus Paleosuchus. The only non-caiman was a gavial resembling modern ones in India, with a long, thin snout for fish-catching.
The findings appear in the scientific journal Proceedings of the Royal Society B.
(Reporting by Will Dunham; Editing by Mohammad Zargham)