Crocodylians Dominated Prehistoric Ecosystem in South America, New Research Reveals

New research has revealed that during the Miocene epoch, over 10 million years ago, crocodylians were the predominant predators in a vast South American ecosystem characterized by immense herbivores and formidable mammalian hunters. This ecosystem thrived around a large lake that supported various species, including giant turtles and a variety of predatory animals.

Oscar Wilson, a postdoctoral researcher at the University of Helsinki, noted, “There was so much prey available that mammalian predators couldn’t have eaten it all. Our new study shows that crocodylians in particular were the region’s most important predators, especially when it came to hunting large prey.”

A Diverse Array of Herbivores

The shores of this prehistoric lake were home to a significant variety of herbivorous species. Among them were giant ground sloths and glyptodonts, which are large, armored relatives of modern armadillos. Several species of ungulates inhabited the area as well; these hoofed mammals included astrapotheres, known as “lightning beasts,” and toxodontids, some of which reached weights exceeding one metric ton.

This abundance of sizable prey supported similarly impressive predators in the ecosystem.

Purussaurus: The Apex Predator

The largest known predator from this ecosystem, Purussaurus neivensis, is related to contemporary caimans. Estimated to reach lengths of about seven meters and weighing around 1,800 kilograms, Purussaurus occupied a critical position in the food chain. The study suggests that this massive crocodylian may have significantly influenced herbivore populations across the ecosystem.

Insights from Fossil Evidence

To understand the dynamics of predation during this period, researchers analyzed fossilized specimens maintained in museum collections. They examined bite and tooth marks on the remains of herbivores to establish direct evidence of predator-prey interactions.

The study focused on fossils ranging from 10.5 million to 16 million years old. Wilson stated, “The frequency of marks likely made by Purussaurus suggests that it was an important predator in these tropical ecosystems.”

The findings have been published in the Journal of Vertebrate Paleontology.