So what ate it? Well, back around the same time and place their also existed one of the largest Crocodylians ever; Purussaurus brasiliensis measured somewhere in the ballpark of 12m. And given that P. pattersoni was found in semi-aquatic riverside habitats, they may have interacted. It is believed that P. pattersoni went extinct because they were so big. They were too large to burrow and were unable to outrun predators like many of the lither, hoofed mammals could.
P. pattersoni was named in honor of Brian Patterson, a paleontologist who worked in the region of its discovery back in the 1970s.