The younger Gorgosaurus knew what it favored for dinner. About 75 million years in the past in what’s now Canada’s Alberta province, this fearsome T. rex cousin set about looking turkey-sized yearlings of a feathered plant-eating dinosaur known as Citipes.
With such prey quite a few, the Gorgosaurus might be choosy about what it ate. It dismembered the helpless Citipes and swallowed its meaty legs complete, ignoring the remainder of the carcass.
Scientists mentioned on Friday (Dec 8) they’ve unearthed fossilized stays of a juvenile Gorgosaurus that was 5 to 7 years outdated and about 4.5 metres lengthy. Amazingly, it included the animal’s abdomen contents, revealing its final meals.
Gorgosaurus and the extra well-known Tyrannosaurus, which lived a number of million years later, are members of a meat-eating dinosaur group known as tyrannosaurs. This fossil has offered perception into the ecology of this group, exhibiting that the feeding technique and food regimen of tyrannosaurs modified dramatically throughout their lifespan. That is the primary tyrannosaur skeleton with prey objects preserved inside its abdomen.
Primarily based on tooth marks left on bones, adults are identified to have hunted huge plant-eating dinosaurs.
“Grownup tyrannosaurs have been well-equipped for seizing and killing giant prey, like duckbilled dinosaurs and horned dinosaurs. Their skulls and enamel have been able to withstanding the most important torsional stresses related to biting and holding onto giant prey,” mentioned François Therrien, dinosaur palaeoecology curator on the Royal Tyrrell Museum in Alberta and co-leader of the research revealed within the journal Science Advances.
“In distinction, the weaker bites and enamel of younger tyrannosaurs have been very best for slashing bites, not holding onto prey. They might have been well-equipped for looking smaller dinosaur species and younger dinosaurs,” Therrien added.
The research signifies that tyrannosaurs occupied completely different ecological niches throughout their lifespan: “mesopredators” – mid-size predators – whereas younger, turning into apex predators as adolescents and adults. Meaning juvenile tyrannosaurs didn’t compete with their elders for a similar prey.
“Younger tyrannosaurs had blade-like enamel, flippantly constructed skulls, comparatively weak bites, lengthy legs and appeared extra ‘athletic’ than grownup tyrannosaurs, which have been very robustly constructed, had huge skulls, thicker enamel – typically described as ‘killer bananas’ due to their form – and highly effective bites that allowed them to crush bones,” Therrien mentioned.
Gorgosaurus, a bit smaller than Tyrannosaurus, dominated its ecosystem. It walked on two legs, had quick arms with two-fingered fingers, an enormous cranium one metre lengthy, reached 9-10 metres in size and weighed 2-3 tons. This juvenile Gorgosaurus weighed about 330 kg, with a cranium round 50 cm lengthy.
The fossil was unearthed at Dinosaur Provincial Park in southern Alberta. The area throughout the Cretaceous Interval was a forested coastal plain close to the western shore of an unlimited inland sea that cut up North America into two halves.
The abdomen contents, discovered between the ribcage and hip bones, included the leg and foot bones of two Citipes yearlings. Citipes was a small, birdlike dinosaur that walked on two legs and had a head resembling a parrot.
“For the reason that Citipes would have had giant broods laying some 30 eggs in a nest, their hatchlings would have been considerable within the ecosystem and ripe for the choosing by younger tyrannosaurs,” mentioned College of Calgary dinosaur palaeontologist and research co-leader Darla Zelenitsky.
Primarily based on the differing abdomen acid harm to the Citipes bones, the yearlings have been eaten at completely different occasions, and the Gorgosaurus died from unknown causes hours or days after its final meal.
“The bones discovered within the abdomen are whole legs. Possibly a full Citipes was too giant to go by the throat of a younger Gorgosaurus, so the predator selectively dissected away the meatiest elements of the carcass. This Gorgosaurus was keen on drumsticks,” Zelenitsky mentioned.
“Whereas adults have been extra indiscriminate feeders, consuming all elements of a giant herbivore’s carcass – typically pulverizing and swallowing bones within the course of – younger people have been way more surgical in how they fed,” Zelenitsky added.
