Giant Ancient Crocodile Ruled South America’s Miocene Predator Hierarchy

More than 10 million years ago, South America hosted an ecosystem teeming with massive animals and powerful predators. During the Miocene epoch, a sprawling lake dominated much of the continent, its waters sustaining giant turtles and crocodylians while diverse hunters patrolled the shoreline.

These predators included anacondas, saber-toothed mammals, flightless “terror birds,” and sebecids—terrestrial relatives of crocodylians. Despite fierce competition, recent research reveals that crocodylians held a dominant role in this ecosystem, serving as the most influential group of predators in the region.

“There was so much prey available that mammalian predators couldn’t have consumed it all,” explains 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.”

An Ancient Ecosystem Thriving With Giant Herbivores

The lake shores supported a rich assortment of plant-eating animals. Giant ground sloths roamed alongside glyptodonts—heavily armored relatives of armadillos—as well as various groups of extinct ungulates. While ungulates are typically hoofed mammals, many prehistoric South American species bore little resemblance to modern animals like horses and deer.

Among them were astrapotheres (“lightning beasts”) and toxodontids. Some of these ancient herbivores grew to enormous sizes, exceeding one metric ton in weight.

This abundance of large prey supported predators that were equally formidable in scale.

The Towering Crocodylian At the Summit

The largest known predator in this ecosystem was Purussaurus neivensis, a colossal crocodylian closely related to modern caimans. It reached lengths of approximately seven meters and weighed roughly 1,800 kilograms.

Its enormous size placed it at the top of the food chain, suggesting it may have influenced more than just individual prey encounters. The new study proposes that Purussaurus could have been impactful enough as a predator to regulate herbivore populations throughout the ecosystem.

This insight offers a window into how formidable giant crocodylians might have shaped ancient tropical communities, rather than merely coexisting with other large predators.

Fossilized Bite Marks Unveil Ancient Predation

To identify which animals were responsible for attacks, researchers examined fossils housed in museum collections. The evidence comes from bite marks and tooth impressions preserved on the fossilized remains of herbivores.

These traces are particularly significant because they represent the only direct evidence of predator-prey interactions. Instead of relying solely on the size, anatomy, or assumed hunting behaviors of extinct animals, scientists can analyze the marks on bones to detect actual feeding or attack patterns.

The fossils studied ranged in age from 10.5 million to 16 million years old.

“The frequency of marks likely caused by Purussaurus suggests that it was a key predator in these tropical ecosystems,” Wilson notes.

The study was published in Journal of Vertebrate Paleontology.p>

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