An investigation of the Department of Vertebrate Paleontology of the Museum of Natural History of New York has discovered seven species of crocodiles of 13 million years in a fossiliferous deposit of the Peruvian Amazon . Before the Amazon River developed as it is today, biodiversity was linked to swampy environments with an abundance of mollusks.
The find shows that 13 million years ago , seven species of crocodiles inhabited the marshy waters of what is now northeastern Peru. This megadiverse environment, discovered after more than a decade of work in the western Amazon, has brought to light the largest concentration of crocodile species coexisting at any time or place in Earth’s history. The abundance of certain resources, such as bivalves and snails that currently only form a small part of the diet of these large reptiles, was the cause that favored this enormous biodiversity. The study, led by Rodolfo Salas-Gismondi and published in the scientific journal Proceedings of the Royal Society B, contributes to the understanding of the history of the great Amazonian diversity.
The modern Amazon basin contains one of the richest biota in the world, but very little is known about its origins, according to John Flynn, curator of the Fossil Mammal Collection at the American Museum of Natural History and one of the authors of the research: “ Because this place is currently a dense tropical forest, the opportunity to find ancient rocks – and fossils that those rocks can preserve – is very limited. So what we find from time to time is not necessarily what we would have expected ”.
Before the Amazon River formed 10.5 million years ago , the western proto-Amazon was home to a complex ecosystem of wetlands – known as the Pebas System – that contained swamps, lakes, bays and rivers that led their waters north to flow into the Caribbean Sea. This configuration was in stark contrast to the modern drainage that runs eastward from the Andes to the Atlantic Ocean.
Since 2002, an international team made up of Peruvian, North American and European scientists has been excavating rocky outcrops around the Amazonian city of Iquitos (Peru) that preserve evidence of life during the Miocene (between 15 and 11 million years ago). . His work has produced excellent results, as in addition to the seven species of crocodiles, three species totally new to science have been described, among them a strange alligator with a very short and wide snout, shovel-shaped jaw and globular teeth on the back called Gnatusuchus pebasensis. This flat alligator is believed to have used its jaw to move mud from swampy bottoms and dig for bivalves and other mollusks. It appears that the appearance of Gnatusuchus and other durophagous or shell-crusher alligators is related to a peak in the diversity and abundance of mollusks in the Miocene swamps, which occurred before this old ecosystem gave way to the Amazon river drainage system.
The other two new species of grinder alligators are the primitive Kuttanacaiman iquitosensis and Caiman wannlangstoni, related to some modern alligators. In addition, researchers have found the first fossil remains of the dwarf caiman Paleosuchus, which had a longer and taller snout, suitable for capturing a variety of prey such as fish and other vertebrates.
