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

During the Miocene epoch, approximately 10.5 to 16 million years ago, South America was a perilous place teeming with diverse predators. Extensive lakes covered large portions of the continent, providing a home for colossal turtles and formidable crocodylians. This aquatic environment attracted a host of predators, including anacondas, saber-toothed mammals, colossal flightless birds, and sebecids - terrestrial kin of modern crocodylians.

However, a recent study published in the Journal of Vertebrate Paleontology suggests that crocodylians dominated the food chain in this ecosystem. This assertion is supported by the abundant prey available, which mammalian predators could not consume entirely. According to 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."

Herbivores thrived along the lake's shores, with giant ground sloths, glyptodonts - relatives of armadillos, and several species of ungulates such as astrapotheres (lightning beasts) and toxodontids present. These ungulates could weigh over a tonne. Yet, their predators were equally colossal. The largest predator of the time was a 7-meter-long, 1,800-kilogram crocodylian named Purussaurus neivensis. This relative of modern caimans may have even influenced the size of herbivore populations, according to the study.

The evidence supporting these claims comes from an analysis of fossils housed in museum collections. The only direct evidence of predator-prey interactions are the bite and tooth marks left on the herbivore fossils. The fossils under examination date back between 10.5 million and 16 million years ago. The frequency of marks likely made by Purussaurus suggests that it was a significant predator in these tropical ecosystems.