By Will Dunham Reuters
The younger Gorgosaurus knew what it preferred for dinner. About 75 million years in the past in what’s now Canada’s Alberta province, this fearsome T. rex cousin set about searching turkey-sized yearlings of a feathered plant-eating dinosaur known as Citipes.
With such prey quite a few, the Gorgosaurus could possibly be choosy about what it ate. It dismembered the helpless Citipes and swallowed its meaty legs entire, ignoring the remainder of the carcass.
Scientists stated on Friday they’ve unearthed fossilized stays of a juvenile Gorgosaurus that was 5 to 7 years outdated and about 15 ft (4.5 meters) lengthy.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.
Based mostly on tooth marks left on bones, adults are identified to have hunted large plant-eating dinosaurs.
“Grownup tyrannosaurs had been well-equipped for seizing and killing giant prey, like duckbilled dinosaurs and horned dinosaurs. Their skulls and tooth had been able to withstanding the main torsional stresses related to biting and holding onto giant prey,” stated François Therrien, dinosaur palaeoecology curator on the Royal Tyrrell Museum in Alberta and co-leader of the research printed within the journal Science Advances.
“In distinction, the weaker bites and tooth of younger tyrannosaurs had been superb for slashing bites, not holding onto prey. They’d have been well-equipped for searching smaller dinosaur species and younger dinosaurs,” Therrien added.
The research signifies that tyrannosaurs occupied totally different ecological niches throughout their lifespan: “mesopredators” – mid-size predators – whereas younger, turning into apex predators as adolescents and adults. Which means juvenile tyrannosaurs didn’t compete with their elders for a similar prey.
“Younger tyrannosaurs had blade-like tooth, flippantly constructed skulls, comparatively weak bites, lengthy legs and appeared extra ‘athletic’ than grownup tyrannosaurs, which had been very robustly constructed, had huge skulls, thicker tooth – usually described as ‘killer bananas’ due to their form – and highly effective bites that allowed them to crush bones,” Therrien stated.
Gorgosaurus, a bit smaller than Tyrannosaurus, dominated its ecosystem. It walked on two legs, had quick arms with two-fingered fingers, an enormous cranium three ft (one meter) lengthy, reached 30-33 ft (9-10 meters) in size and weighed 2-3 tons. This juvenile Gorgosaurus weighed about 730 kilos (330 kg), with a cranium round 20 inches (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 enormous 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.
“Because the Citipes would have had giant broods laying some 30 eggs in a nest, their hatchlings would have been plentiful within the ecosystem and ripe for the choosing by younger tyrannosaurs,” stated College of Calgary dinosaur paleontologist and research co-leader Darla Zelenitsky.
Based mostly on the differing abdomen acid injury to the Citipes bones, the yearlings had been eaten at totally different instances, and the Gorgosaurus died from unknown causes hours or days after its final meal.
“The bones discovered within the abdomen are total legs. Possibly a full Citipes was too giant to cross 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 stated.
“Whereas adults had been extra indiscriminate feeders, consuming all elements of a giant herbivore’s carcass – usually pulverizing and swallowing bones within the course of – younger people had been much more surgical in how they fed,” Zelenitsky added.