The Tyrannosaurus Rex, or T. Rex, was a formidable dinosaur that roamed western North America during the Late Cretaceous period. Its diet has long fascinated scientists and the public. What did the T. Rex truly eat?
The Primary Diet
The T. Rex was an apex predator. Its diet primarily consisted of large plant-eating dinosaurs like the horned Triceratops and the duck-billed Edmontosaurus. As a hypercarnivore, it consumed large quantities of meat.
Adult T. Rex individuals were adapted to hunt these large, slower-moving targets, using their powerful build and bone-crushing jaws to subdue and process their meals. Younger tyrannosaurs, however, likely pursued smaller and swifter prey, such as juvenile dinosaurs or smaller creatures like lizards and crocodilians. This shift in diet as they matured allowed different age groups to coexist without competing directly for the same food sources.
Uncovering Its Meals
Paleontologists cannot directly observe the feeding behaviors of extinct dinosaurs, so they rely on fossil evidence to reconstruct the T. Rex’s diet. One significant piece of evidence comes from bite marks found on fossilized bones of other dinosaurs. For instance, T. Rex tooth marks have been identified on the pelvis of Triceratops and the tailbones of Edmontosaurus, sometimes even showing signs of healing, which indicates the prey survived the attack.
Another source of information is coprolites, which are fossilized feces. A T. Rex coprolite, for example, contained crushed bone fragments, likely from an ornithischian dinosaur such as Edmontosaurus. While rare, fossilized stomach contents can offer direct insights. A juvenile Gorgosaurus, a close relative of T. Rex, was discovered with the hind limbs of two smaller dinosaurs in its abdominal cavity, providing direct evidence of its last meal.
Hunter or Scavenger
For decades, paleontologists have debated whether the T. Rex was primarily an active hunter, an opportunistic scavenger, or both. Arguments supporting the T. Rex as a predator point to its immense bite force, estimated between 35,000 and 57,000 Newtons in adults, which could shatter bones. Its powerful jaws and robust teeth were well-suited for taking down large, struggling prey and consuming bone marrow. The sheer size of T. Rex also implies a need for a consistent food supply, which might be difficult to secure through scavenging alone.
Conversely, proponents of the scavenging hypothesis highlight the T. Rex’s large olfactory bulbs, indicating a highly developed sense of smell capable of detecting carrion from great distances. Its relatively small forelimbs, not ideal for grasping struggling prey, have also been cited as an argument against active hunting. Some theories suggested T. Rex might have been too slow to chase down swift prey, though this remains debated. Furthermore, bite marks found on T. Rex bones, indicating cannibalism, often appear in areas like foot and arm bones, suggesting the best meat had already been consumed, consistent with scavenging behavior.
The prevailing scientific view today is that T. Rex, like many large carnivores, was an opportunistic feeder, engaging in both hunting and scavenging. It would likely hunt live prey when possible but would not pass up the opportunity to scavenge an already deceased animal. This flexible feeding strategy would have maximized its chances of survival in its ancient ecosystem.