Fossils once thought to be the skulls of adolescent Tyrannosaurus Rex actually belonged to a different species of dinosaur, scientists have concluded.
First discovered in Montana, WEin 1942, the remains were the subject of debate over whether they came from T. Rex juniors or Nanotyrannus lancensis – smaller relatives of the iconic dinosaurs.
According to a study by the Milner Center for Evolution at the University of Bath, the fossils came from adults. dinosaursmeaning the 66 million year old remains are more likely from Nanotyrannus.
The university’s Dr Nick Longrich said he was “pretty blown away” by the results, based on analysis of growth rings in fossilized bones and modeling of animal growth.
“I didn’t expect it to be this successful,” he said. “If they were young T. Rexes, they would grow like crazy, gaining hundreds of pounds a year, but we don’t see that.
“We tried to model the data in different ways and always got low growth rates.
“This seems to put to rest the hypothesis that these animals were young T. Rex.”
Learn more:
T. Rex’s last meal revealed after stomach contents were preserved in fossil
T. Rex may have used light weapons to mate
In the University of Bath’s modeling, the researchers noted that the dinosaurs studied would have reached a maximum size of around 900 to 1,500 kilograms and five meters, or about 15 percent of the size of an adult T. rex.
Dr Longrich added: “In the same way that kittens look like cats and puppies look like dogs, the juveniles of different tyrannosaurs are distinctive.
“And Nanotyrannus looks nothing like a T. Rex… The arms are actually longer than those of the T. Rex.
“Even the largest T. Rex has shorter arms and smaller claws than these smaller Nanotyrannus.
“It was an animal whose arms were actually quite formidable weapons. It’s actually a completely different animal – small, fast and agile.
“The T. Rex relied on size and strength, but this animal relied on speed.”
The report was published in the journal Fossil Studies.
Fossils once thought to be the skulls of adolescent Tyrannosaurus Rex actually belonged to a different species of dinosaur, scientists have concluded.
First discovered in Montana, WEin 1942, the remains were the subject of debate over whether they came from T. Rex juniors or Nanotyrannus lancensis – smaller relatives of the iconic dinosaurs.
According to a study by the Milner Center for Evolution at the University of Bath, the fossils came from adults. dinosaursmeaning the 66 million year old remains are more likely from Nanotyrannus.
The university’s Dr Nick Longrich said he was “pretty blown away” by the results, based on analysis of growth rings in fossilized bones and modeling of animal growth.
“I didn’t expect it to be this successful,” he said. “If they were young T. Rexes, they would grow like crazy, gaining hundreds of pounds a year, but we don’t see that.
“We tried to model the data in different ways and always got low growth rates.
“This seems to put to rest the hypothesis that these animals were young T. Rex.”
Learn more:
T. Rex’s last meal revealed after stomach contents were preserved in fossil
T. Rex may have used light weapons to mate
In the University of Bath’s modeling, the researchers noted that the dinosaurs studied would have reached a maximum size of around 900 to 1,500 kilograms and five meters, or about 15 percent of the size of an adult T. rex.
Dr Longrich added: “In the same way that kittens look like cats and puppies look like dogs, the juveniles of different tyrannosaurs are distinctive.
“And Nanotyrannus looks nothing like a T. Rex… The arms are actually longer than those of the T. Rex.
“Even the largest T. Rex has shorter arms and smaller claws than these smaller Nanotyrannus.
“It was an animal whose arms were actually quite formidable weapons. It’s actually a completely different animal – small, fast and agile.
“The T. Rex relied on size and strength, but this animal relied on speed.”
The report was published in the journal Fossil Studies.