A exceptional fossil preserving the final meal of a younger tyrannosaur has been found in Canada, revealing the dinosaur had a style for prehistoric quick meals.
Whereas tyrannosaurs had been a few of the most fearsome dinosaurs to roam the planet, with adults boasting huge our bodies, enormous heads and bone-crushing bites, juveniles had been somewhat extra puny, with lengthy, skinny legs, blade-like tooth and slender skulls.
The transformation has lengthy been regarded as related to a shift in eating regimen because the tyrannosaurs matured and required extra power: whereas proof together with chew marks on bones has urged adults hunted and feasted upon monumental herbivores, equivalent to duck-billed and horned dinosaurs, children didn’t have the dental equipment to deal with such prey.
However simply what the juveniles did munch on has been one thing of a thriller.
Now a spectacular fossil that includes the preserved abdomen contents of a younger tyrannosaur has supplied a uncommon perception into their eating regimen.
“That is actually the primary stable proof that we now have of what the eating regimen or feeding behaviour was in a juvenile tyrannosaur,” mentioned Dr Darla Zelenitsky, the co-author of the examine on the College of Calgary.
Thought so far to about 75m years in the past, the fossil of the younger Gorgosaurus libratus was found within the badlands of Dinosaur Provincial Park, Canada, in 2009 by Darren Tanke, a technician working on the Royal Tyrrell Museum of Palaeontology.
The workforce say the younger tyrannosaur had weighed about 350kg, with evaluation of progress rings within the fossilised bones suggesting it died younger, at 5 to seven years previous.
But it surely didn’t die hungry.
“It was through the preparation course of in late 2010 that Darren seen small knuckle bones that had been protruding out of the ribcage of the tyrannosaur,” mentioned Dr François Therrien, the curator of dinosaur palaeoecology on the Royal Tyrrell Museum and co-author of the analysis.
Writing within the journal Science Advances, the workforce report that contained in the ribcage they found the stays of two juvenile citipes: turkey-sized creatures with a parrot-like head that might have been speedy on their toes, somewhat like an emu.
Variations within the extent of abdomen acid harm urged the citipes had been consumed in two separate sittings. Nevertheless, the stays had been largely restricted to the hind legs, suggesting the younger tyrannosaur didn’t eat all of its prey.
“This juvenile tyrannosaurus appears to have had an urge for food for drumsticks of citipes,” mentioned Zelenitsky, including that one chance is that the legs had been the meatiest a part of the prey, with the cranium of the younger gorgosaurus enabling precision feeding.
Whereas the workforce mentioned it was unclear how the tyrannosaur died, it seems to have perished inside per week of its final meal.
The invention is the primary time the fossil of a tyrannosaur has been discovered with the contents of its abdomen preserved. And there may be one other bonus to the discover.
“The legs current within the abdomen symbolize essentially the most full citipes skeleton identified,” mentioned Therrien.
Prof Stephen Brusatte, a palaeontologist on the College of Edinburgh, who just isn’t concerned within the work, mentioned the fossil was direct proof of what a tyrannosaur was consuming.
“Not guesswork or a sequence of assumptions based mostly on interpretation of chew marks or coprolites – fossil faeces – however precise direct in-the-gut proof,” he mentioned. “This can be a tyrannosaur’s final meal, preserved in stone.”
Brusatte mentioned the fossil supported the concept that tyrannosaurs modified their diets as they received older, shifting from small to large prey.
Whereas Brusatte added the insights make intuitive sense, he mentioned it was not inevitable, noting an alternate chance was that younger tyrannosaurs merely feasted on prey killed by adults.
“However that doesn’t appear to be the case right here – the little tyrannosaurs ate little prey, in order that they most likely actively hunted their very own meals and altered the prey they focused as they received greater,” he mentioned. “Because of this tyrannosaurs crammed totally different roles within the meals net as they grew up, which is fairly neat.”