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.
Beetles were among the most skilled of the dinosaur destruction crew. The prehistoric relatives of scarab, darkling, and dermestid beetles were around during the time of Protoceratops and Oviraptor. We know because when those beetles ran out of soft parts to eat, they began to burrow through bone. Some even left larvae inside dinosaur skeletons. A skeleton of Nemegtomaia—a feathery, beaked oviraptorosaur who died while sitting on a nest—was partially obliterated by dermestid-like beetles. Distinctive holes in the dinosaur’s skull and other bones gave the insects away. Exactly why these insects spent so much time dismantling dinosaurs is unclear—perhaps dinosaur carcasses were rare bonanzas in arid prehistoric environments—but beetles certainly left their mark.
Other insects harried dinosaurs while they were alive. Lice lineages began to diverge during the Cretaceous—the heyday of feathered dinosaurs. Paleontologists have yet to pick nits from fossils, but the lice, including the precursors of today’s bird-riding feather lice, required hosts. Fuzzy and fluffy dinosaurs may very well have been comfortable homes for archaic lice species. Inch-long fleas with awful, saw-toothed mouthparts certainly had the equipment to get through the plumage and hides of the Jurassic dinosaurs they lived alongside. While the prehistoric species were different from today’s pests, dinosaurs nevertheless faced familiar battalions of biting and sucking insects. The persistent of lice, fleas, and their ilk is a testament to the pests’ adaptive ability to switch hosts in the course of evolutionary time.
And then there were sharks. The huge “megatooth” shark Carcharocles megalodon evolved about 40 million years after the last non-avian dinosaurs died—the blood-soaked T. rex vs C. megalodon battle that kicks off Steve Alten’s cheesy horror yarn MEG never could have happened—but rare fossils nevertheless show that earlier sharks occasionally fed on dinosaurs. The trick was getting dinosaurs out to sea. There were no aquatic dinosaurs—aside from feathered gliders and flyers, every species we know of was terrestrial—but, now and then, rivers would wash dead dinosaurs out to the ocean. A specimen of the heavily-armored ankylosaur Aletopelta on display at the San Diego Natural History Museum, known as the “Carlsbad ankylosaur,” was found in Cretaceous marine rock. Shark teeth found with the skeleton indicate that sharks fed on the dinosaur when it settled on the bottom, where it played host to a temporary reef of clams and other encrusting organisms. An even more unfortunate juvenile hadrosaur didn’t even get to become a reef. Presented by paleontologist Jason Schein in a poster at last month’s Society of Vertebrate Paleontology meeting in Raleigh, N.C., a young hadrosaur limb bone found in the marine deposits of southeastern New Jersey looks like someone went at it with a Ginsu knife—the bone surface is sliced by multiple shark bites from when the poor dinosaur’s carcass floated into to Cretaceous Atlantic coast. To leave so much damage on the bone itself, the sharks and other marine scavengers must have stripped the dinosaur’s body in a feeding frenzy.
In life and death, in forests as well as at sea, dinosaurs were food for a variety of other creatures. They were spectacular animals, but the fact that they were both the eaters and the eaten in the xhabitats they roamed makes them all the more real. Dinosaurs were not invulnerable monsters; Apatosaurus, Tyrannosaurus, Triceratops and the rest of their Mesozoic clan were actors in a more diverse cast on Earth’s evolutionary stage.
Even now, dinosaurs remain on life’s playbill in avian garb, and thanks to countless gustatory investigations, we know they’re quite tasty—so much so that we’ve organized a national holiday around picking flesh from their skeletons. I hope you enjoy your annual dinosaur dissection today, and when you snap the turkey’s delicate wishbone, remember to give thanks for the theropod on the table and all of its extinct dinosaurian kin.
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