More than 10 million years ago, a vast lake and extensive wetland system covered much of South America, supporting an ecosystem where giant crocodylians dominated the ancient food chain. According to new research published in the Journal of Vertebrate Paleontology, these massive reptiles played the primary role in hunting large prey across tropical ecosystems between 10.5 million and 16 million years ago.
Miocene South America Ruled by Colossal Crocodylians
During the Miocene epoch, the region’s waters and shores teemed with an extraordinary collection of life. Giant turtles and crocodylians occupied the aquatic habitats, while anacondas, saber-toothed mammals, flightless “terror birds”, and sebecids—terrestrial relatives of crocodylians—hunted along the margins. Despite competition from various mammalian and avian hunters, researchers concluded that mammalian predators alone could not have consumed the immense biomass of available prey, allowing crocodylians to claim the undisputed top tier of the food web.
Fossil Evidence Reveals Apex Predators in Action
To understand these ancient interactions, scientists analyzed museum collections of fossilized bones belonging to large hoofed mammals from the La Venta region of Colombia’s Huila department. Because direct behavioral observations are impossible in deep time, researchers examined physical bite and tooth marks left on herbivore remains, providing direct physical evidence of predator-prey dynamics.
The analyzed specimens included a skull, a leg bone, and two jawbones bearing circular and bisected puncture wounds, along with areas of crushed bone. These marks matched the anatomy of Purussaurus neivensis, an enormous extinct caiman relative that could exceed six to seven meters in length and weigh roughly 1,800 kilograms. Bite forces needed to produce these punctures approached or exceeded 40,000 newtons per tooth.
Researchers noted that most of the bite marks concentrated on the animals’ heads and jaws, mirroring how modern saltwater and Nile crocodiles ambush large prey. One jawbone belonging to an extinct ungulate also featured a second, distinct set of parallel grooves attributed to a smaller, land-dwelling crocodile relative called Langstonia huilensis, which scientists interpreted as evidence of a separate scavenging event.
A Prehistoric Buffet of Megafuna
The lakeshores and wetlands supported an impressive variety of heavy herbivores that could weigh well over a metric ton. Among the targets of these apex predators were rhinoceros-sized toxodontids, astrapotheres, and other ancient ungulates, as well as enormous ground sloths and heavily armored glyptodonts.
The sheer size and hunting frequency of Purussaurus neivensis enabled the reptiles to exert top-down control over megafaunal populations. As primary apex predators, these giant crocodylians helped regulate large herbivore populations and shaped ancient tropical communities across Miocene South America before changing geography, rising Andean mountains, and shifting river systems eventually transformed the wetlands into the modern Amazon basin.
Key Miocene Predators and Prey
- Purussaurus neivensis: An apex caiman relative reaching up to 7 meters in length and weighing approximately 1,800 kg, capable of bite forces exceeding 40,000 newtons per tooth.
- Pericotoxodon platignathus: A rhinoceros-sized native ungulate targeted by large crocodylians.
- Xenastrapotherium kraglievichi and Granastrapotherium snorki: Elephant-like megaherbivores weighing between 600 and 1,800 kg.
- Langstonia huilensis: A smaller, land-dwelling crocodile relative linked to evidence of scavenging on herbivore remains.
- Other Regional Hunters: Anacondas, saber-toothed mammals, flightless terror birds, and sebecids.
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