Happy Dinosaur Dissection Day! Thanksgiving is upon us—a time to reflect, cope with loved ones, and stuff ourselves silly with theropod meat. While the turkey on the table may not seem quite as fierce as the Cretaceous “terrible claw” Deinonychus, they are both feathered dinosaurs, cousins separated by about 110 million years. Birds were the only lineage of dinosaur to survive the catastrophe that wiped out their relatives 66 million years ago. Of course, our species wasn’t the first to dine on dinosaur. We’re continuing a longstanding tradition. From armor-encased ankylosaurs to the terrible tyrannosaurs, dinosaurs were smorgasbords for other species millions and millions of years before the first Thanksgiving.
No prehistoric predator is as cherished at Tyrannosaurus rex. From the time the sharp-toothed theropod was named in 1905, we have always regarded the tyrant as the consummate destroyer of hapless Edmontosaurus and unlucky Triceratops. New research has only solidified our evidence that T. rex was both a formidable hunter and a bone-shattering scavenger, much like today’s spotted hyenas, and new studies of the dinosaur’s bite force and feeding habits make the Cretaceous carnivore seem deadlier than ever. Despite their terrifying nature, T. rex were helpless against microscopic creatures that made a home in tyrannosaur jaws.
Sue, the most complete T. rex ever found, suffered the most. Her lower jaws are pockmarked with smooth-edged holes. At first, some paleontologists proposed that the holes were wounds made by the bite of another T. rex: Perhaps Sue was killed by rogue member of her own kind. But the holes didn’t match the shape of a tyrannosaur jaw, and there was no sign of crushing damage from a powerful bite. Instead, as veterinarian Ewan Wolff and colleagues argued, the holes were created by a parasite similar to one that plagues modern birds. Called Trichomonas gallinae, the protozoan takes up residence in the mouths and upper digestive tracts of its hosts, creating so many lesions and ulcers that severely afflicted birds can no longer eat. The same fate may have befallen Sue. Regardless of whether the famous T. rex picked up the disease through cannibalism, a fight with an infested dinosaur, or some other route, the microscopic organism drove the greatest predator of the Late Cretaceous to starvation.
The tale of Trichomonas and T. rex is a potent reminder that, much as we might refer to the Mesozoic as the Age of Dinosaurs, the tyrant dinosaurs and their varied kin were not impervious rulers. We might pay more attention to the question of what dinosaurs ate—exactly how a 100-foot, long-necked sauropod such as Futalognkosaurus consumed enough food each day to fuel its hot-running metabolism, for example, remains a mystery—but this focus has obscured the fact that their lives were integrated into complex ecosystems. A variety of other creatures—including sharks!—fed on dinosaurs.
Some dinovores were as terrible as the dinosaurs themselves. Deinosuchus, a close prehistoric cousin of today’s alligators that lived between 80 and 73 million years ago, could grow to 40 feet in length. It haunted coastal swamps from Montana and Utah to Georgia and North Carolina, back when a shallow sea split North America in two. The sheer size of these aquatic ambush predators would have allowed them to snatch unwary dinosaurs, especially juveniles. While we can’t be sure that the alligatoroid actually caught the dinosaur or was scavenging, tooth-marked hadrosaur bones found in Mexico confirm that Deinosuchus consumed dinosaurs when the opportunity arose. Smaller crocodylians probably did the same, although none were quite as imposing as the “terror croc.”
Even mammals got in on the dinosaur-eating act. It’s true that dinosaur dominance prevented mammal body size from getting very large, and feathery carnivores similar to Velociraptor and Troodon may have snacked on our furry relatives. But mammals still evolved into a diverse array of forms—including badger-size beasts that ate dinosaur babies. Found in the Cretaceous rock of Manchuria, a skeleton of the sharp-toothed mammal Repenomamus robustus was found with the remains of baby dinosaurs in its stomach. Even smaller mammals sometimes dined on dinosaurs. Isolated dinosaur bones excavated from the Cretaceous rock of Alberta, Canada, are marked by parallel gouges which match teeth of multituberculates—mammals that probably looked like Mesozoic squirrels in life, but belonged to a distant part of the mammal family tree that has since gone extinct. The little biters didn’t swarm over the dinosaurs, but gnawed on carcasses that had already begun to rot.