Northeastern Peru was a crocodile paradise 13 million years ago, as researchers have found the remains of seven different croc species that simultaneously thrived at the once swampy and food-filled site.
The discovery, reported in the journal Proceedings of the Royal Society B, is the largest known number of crocodile species to have ever co-existed in one place at any time in Earth's history.
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"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," lead author Rodolfo Salas-Gismondi said in a press release.
"At this moment," he continued, "most known caiman groups co-existed: ancient lineages bearing unusual blunt snouts and globular teeth along with those more generalized feeders representing the beginning of what was to come."
The site was so croc-rich because it was also a mollusk haven then, although many of the snails, clams and other small creatures wound up as dinner for the crocodiles.
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In the paper, Salas-Gismondi and his team describe the seven croc species, three of which are new to science. The "strangest," they say, was Gnatusuchus pebasensis. It had globe-shaped teeth and used its snout to shovel through mud bottoms, digging for mollusks.
They also mention the crocodile Paleosuchus, which had a longer and higher snout shape that was suitable for catching a variety of prey, like fish and other active swimming vertebrates.
Today the site is home to a vast rain forest, so the fossils shed light on the region's swampy past.
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As co-author John Flynn of the American Museum of Natural History said, "anytime you get a special window like these fossilized ‘mega-wetland' deposits, with so many new and peculiar species, it can provide novel insights into ancient ecosystems."
Never again would seven species of crocodiles in the wild live together in one place. At present, six species of caimans live in the whole Amazon basin, although only three ever co-exist in the same area and they rarely share the same habitats.
Image: A reconstruction of the head of Gnatusuchus pebasensis, a 13-million-year-old, short-faced crocodile that used its snout to shovel through mud bottoms, digging for clams and other mollusks. Model by Kevin Montalbán-Rivera. Credit: Aldo Benites-Palomino