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Researchers have discovered a tyrannosaur’s final meal completely preserved inside its abdomen cavity.
What was on the menu 75 million years in the past? The hind legs of two child dinosaurs, in keeping with new analysis on the fossil revealed Friday within the journal Science Advances.
Dinosaur guts and laborious proof of their diets are not often preserved within the fossil report, and it’s the first time the abdomen contents of a tyrannosaur have been uncovered.
The revelation makes this discovery notably thrilling, mentioned co-lead creator Darla Zelenitsky, a paleontologist and affiliate professor on the College of Calgary in Alberta.
“Tyrannosaurs are these giant predatory species that roamed Alberta, and North America, in the course of the late Cretaceous. These have been the long-lasting apex or high predators that we’ve all seen in films, books and museums. They walked on two legs (and) had very quick arms,” Zelenitsky mentioned.
“It was a cousin of T. rex, which got here later in time, 68 to 66 million years in the past. T. rex is the most important of the tyrannosaurs, Gorgosaurus was somewhat bit smaller, possibly full grown would have been 9, 10 meters (33 ft).”
The tyrannosaur in query, a younger Gorgosaurus libratus, would have weighed about 772 kilos (350 kilograms) — lower than a horse — and reached 13 ft (4 meters) in size on the time of loss of life.
The creature was between the ages of 5 and seven and gave the impression to be choosy in what it consumed, Zelenitsky mentioned.
“Its final and second-to-last meal have been these little birdlike dinosaurs, Citipes, and the tyrannosaur really solely ate the hind limbs of every of those prey objects. There’s actually no different skeletal stays of those predators throughout the abdomen cavity. It’s simply the hind legs.
“It will need to have killed … each of those Citipes at completely different instances after which ripped off the hind legs and ate these and left the remainder of the carcasses,” she added. “Clearly this teenager had an urge for food for drumsticks.”
The 2 child dinosaurs each belonged to the species referred to as Citipes elegans and would have been youthful than 1 12 months outdated when the tyrannosaur hunted them down, the researchers decided.
The virtually full skeleton was present in Alberta’s Dinosaur Provincial Park in 2009.
That the tyrannosaur’s abdomen contents have been preserved wasn’t instantly apparent, however employees on the Royal Tyrrell Museum in Drumheller, Alberta, observed small protruding bones when getting ready the fossil within the lab and eliminated a rock inside its rib cage to take a better look.
“Lo and behold, the entire hind legs of two child dinosaurs, each underneath a 12 months outdated, have been current in its abdomen,” mentioned co-lead creator François Therrien, the museum’s curator of dinosaur paleoecology, in an announcement.
The paleontologists have been capable of decide the ages of each the predator and its prey by analyzing skinny slices sampled from the fossilized bones.
“There’s development marks just like the rings of a tree. And we will basically inform how outdated a dinosaur is from taking a look at these, the construction of the bone,” Zelenitsky mentioned.
The fossil is the primary laborious proof of a long-suspected dietary sample amongst giant predatory dinosaurs, mentioned paleoecologist Kat Schroeder, a postdoctoral researcher at Yale College’s division of Earth and planetary science, who wasn’t concerned within the analysis.
The teenager tyrannosaur didn’t eat what its dad and mom did. Paleontologists imagine its weight loss program would have modified over its life span.
“Massive, sturdy tyrannosaurs like T. rex have chew forces sturdy sufficient to hit bone when consuming, and so we all know they bit into megaherbivores like Triceratops,” Schroeder mentioned by way of e-mail. “Juvenile tyrannosaurs can’t chew as deep, and due to this fact don’t go away such feeding traces.”
She mentioned that scientists have beforehand hypothesized that younger tyrannosaurs had completely different diets from absolutely developed adults, however the fossil discover marks the primary time researchers have direct proof.
“Mixed with the relative rarity of juvenile tyrannosaur skeletons, this fossil could be very important,” Schroeder added. “Enamel can solely inform us a lot in regards to the weight loss program of extinct animals, so discovering abdomen contents is like selecting up the proverbial ‘smoking gun.’”
The contents of the tyrannosaur’s abdomen cavity revealed that at this stage in life, juveniles have been looking swift, small prey. It was possible as a result of the predator’s physique wasn’t but well-suited for greater prey, Zelenitsky mentioned.
“It’s well-known that tyrannosaurs modified so much throughout development, from slender kinds to those sturdy, bone-crushing dinosaurs, and we all know that this modification was associated to feeding conduct.”
When the dinosaur died, its mass was solely 10% of that of an grownup Gorgosaurus, she mentioned.
The voracious urge for food of teenage tyrannosaurs and different carnivores has been thought to elucidate a puzzling feature of dinosaur diversity.
There are comparatively few small and midsize dinosaurs within the fossil report, notably within the Mid- to Late Cretaceous Interval — one thing paleontologists have decided is as a result of looking actions of younger tyrannosaurs.
“In Alberta’s Dinosaur Provincial Park, the place this specimen is from, we’ve got a really properly sampled formation. And so we’ve got a reasonably good concept of the ecosystem there. Over 50 species of dinosaurs,” Zelenitsky mentioned.
“We’re lacking mid-sized … predators from that ecosystem. So yeah, there’s been the speculation that, the juvenile tyrannosaurs stuffed that area of interest.”