Giant crocodylians dominated the food chain in Miocene South America, fossil evidence suggests

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: 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. 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.

The research is based on an analysis of fossils held in museum collections. Bite and tooth marks left by predators on herbivore fossils are the only direct evidence of interactions between species. The fossils examined were between 10.5 million and 16 million years old.

"The frequency of marks likely made by Purussaurus suggests that it was an important predator in these tropical ecosystems," Wilson comments. Physical evidence of crocodylian predation on ungulates in the Middle Miocene of Colombia, Journal of Vertebrate Paleontology (2026). DOI: 10.1080/02724634.2026.2701154 Journal information: Journal of Vertebrate Paleontology MA in English, copy editor since 2021 with experience in higher education and health content.