Purussaurus neivensis Ruled Miocene South America at 7 Meters, Study Finds

Q: What mysterious ecological shift caused the extinction of the 1,800-kilogram Purussaurus after it ruled South America as the ultimate apex predator?

There is no single confirmed “mysterious” cause. The best-supported explanation is a broad ecological reorganization in late Miocene South America that destroyed the wetland world Purussaurus depended on. Purussaurus thrived in vast lakes, swamps, floodplains and river-margin habitats such as the Pebas and related wetland systems. Geological evidence indicates that the uplift of the Andes gradually reshaped drainage across northern South America, helping drain or fragment those mega-wetlands and reorganize them into the developing Amazon river system. That would have shrunk the shallow aquatic habitats where a giant ambush predator could dominate. Researchers also point to climate change as a likely added pressure. Cooling trends toward the end of the Miocene may have altered rainfall, water levels, vegetation and prey distributions. If the giant herbivores and other wetland fauna declined or shifted habitats, Purussaurus would have lost both food resources and the environmental conditions suited to its hunting style. So the “shift” was likely not one sudden mystery event, but a combination of tectonic landscape change, hydrological reorganization and climatic cooling. Together, those changes appear to have collapsed the ecosystem that had supported an 1,800-kilogram crocodylian as South America’s top predator.

3 articles · Updated · ScienceAlert · Aug 24

Four fossils from Colombia's La Tatacoa Desert, dated 10.5 million to 16 million years old, carry bite marks that researchers attribute to Purussaurus neivensis, identifying it as a top predator of Miocene South America.
The remains—a partial skull, a femur and two lower jawbones from three ungulate species—suggest the giant caiman relative attacked large herbivores, some weighing more than 1 ton.
Researchers reconstructed a hunting style in which the roughly 7-meter, 1,800-kilogram reptile likely seized prey by the head, crushed bone with an immense bite and used a death roll to dismember carcasses.
The findings indicate crocodilians, not mammalian carnivores, were major hunters of large prey in South America before the Great American Biotic Interchange reshaped the continent's ecosystems.