Giant crocodylians dominated the food chain in Miocene South America, fossil evidence suggests
South America was a frightening place during the Miocene. More than 10 million years ago, a vast lake covered much of the continent, home to giant turtles and crocodylians.
A wide range of predators hunted on the lake's shores, including anacondas, saber-toothed mammals, flightless "terror birds" and sebecids—terrestrial relatives of crocodylians.
A recent study shows that crocodylians were, in fact, the most significant group of predators in this habitat.
"There was so much prey available that mammalian predators couldn't have eaten it all," says Oscar Wilson, a postdoctoral researcher at the University of Helsinki.
"Our new study shows that crocodylians in particular were the region's most important predators, especially when it came to hunting large prey."
The study was published in Journal of Vertebrate Paleontology.
Bite traces reveal the predator
A great variety of herbivores lived on the lake's shores: giant ground sloths, glyptodonts—relatives of armadillos—and several groups of ungulates, such as astrapotheres ("lightning beasts") and toxodontids. The ungulates of this era could weigh well over a tonne.
But the predators were giants, too. The largest predator of the time was a 7-meter-long (23-foot-long), 1,800-kilogram (4,000-pound) crocodylian, Purussaurus neivensis, a relative of modern caimans. At the top of the food chain, it may even have influenced the size of herbivore populations, the new study suggests.
Reconstruction of Purussaurus neivensis attacking Pericotoxodon platignathus. Credit: Miguel Hernandez
Jawbone of Xenastrapotherium kraglievichi that features marks of both predation by Purussaruus neivensis and possible scavenging by Langstonia huilensis . Credit: Oscar Wilson