Struggling with identity makes being a teenager tough — even for a 66-million-year-old teen.
The partial skull of a dinosaur unearthed this summer, north of the eastern Montana town of Jordan, faces just such a struggle. The teeth and bones seem to point to the discovery being from a young Tyrannosaurus rex, that huge meat-eating dinosaur that has fueled many dark dreams.
Or is the skull that of a Nanotyrannus, a smaller, more nimble species that shares similarities with T. rex?
“My gut says it’s a juvenile,” said Greg Liggett, a Bureau of Land Management paleontologist based in Billings. “It makes a lot of sense. There had to have been babies before they got big, so where are they?”
The fossil of a lower jaw and teeth was unearthed by a team from the University of Kansas this summer and is being cleaned in the school’s lab.
“It’s a pretty dramatic specimen,” Liggett said, one of only three similarly sized Nanotyrannus, or young T. rexes, ever unearthed. “So not many have been found, and we’ve been looking for 100 years.”
Heaven in Hell
Montana’s Hell Creek Formation is a hotbed for dinosaur bones. During that geologic time period 66 million years ago, tons of sediment poured into what was then a low-lying area that stretched from Saskatchewan in the north to Wyoming in the south. Captured in those massive sediment flows were duck-billed and three-horned fringed beasts.
In a 1908 article for Scribner’s Magazine, William Hornady described finding fossil remains while hunting mule deer years earlier in eastern Montana’s badlands.
“It was very evident that in the age of reptiles some gigantic species had inhabited that spot,” he wrote after being shown a fossilized skull half as large as a full-grown elephant.
After returning to New York City, he informed a colleague. In response to the report, the American Museum sent Barnum Brown to investigate.
“Mr. Brown found the remains of a new genus of gigantic reptiles — predatory and carnivorous to the utmost … in due time the world was introduced to Tyrannosaurus rex, the Tyrant Lizard, late of Hell Creek.”
And so the legend was born and continues to live on.
“Montana is a hotbed for T. rex,” said David Burnham, preparator of vertebrate paleontology at the KU Biodiversity Institute. “In fact, I call it T. rex world.”
It was Burnham who led the KU crew in 2016 that discovered the possibly young T. Rex. It was almost by accident. Suffering equipment delays on a separate dig, he sent everyone out to look for fossils.
“We started to find bones, teeth and claws,” he said. “Everyone was hyper excited. They were in soft sand. You could dig it with hand tools.”
Toward the end of what turned into a three-week exploration, Burnham spotted what he thought may be a skull. Rather than expose it to the weather and have to leave it until the following summer, he decided to wait. Encased in harder rock, once the fossil was cleaned in the lab this year, the stone revealed a set of jaws riddled with large teeth.
“We had some kind of an idea what it was, but we were confused,” he said. “We called it a mystery theropod.”
Theropods are meat-eating dinosaurs, typically the two-legged kind.
First to best
In addition to being a hotbed for T. rexes for more than 100 years, Montana’s Hell Creek Formation also yielded another first. In 1942 the Cleveland Museum unearthed a specimen in eastern Montana’s Carter County that was christened the first Nanotyrannus.
In 2001, a more complete skeleton was uncovered in Carter County, this one by the Burpee Museum of Natural History. Based on the earlier classification of the 1942 find, it was initially called a Nanotyrannus. But since then the museum has decided the skeleton is instead a teenage T. rex, only 11 years old and still growing.
A copy of the skull of the young T. rex, named Jane, is on display in the BLM office in Miles City. Archaeologist Doug Melton often asks paleontologists visiting the office for their summer dig permits what they think: Is Jane a young T. rex, or a Nanotyrannus? He’s gotten both answers.
“I really don’t have any theories,” he said. “But you would expect, since there’s a pretty good number of T. rexes that have come from Montana, that you would see an age range.”
One of the factors dividing scientists is the number of teeth in the skulls of the smaller dinosaurs — there are more than the adult T. rexes. Burnham plans to study in detail the teeth of the fossil his team uncovered to possibly settle the dispute once and for all. The university has a privately-owned true baby T. rex on loan to help with the comparison.
The discovery, and what the study might reveal, has drawn a lot of attention to the University of Kansas program. Burnham had just spoken to someone from Paris on Friday and prior to that had given dozens of interviews and answered numerous emails since the discovery was made public.
“We’re pretty excited about it,” he said.
And more pieces of the unique specimen could be waiting in the same soils.
“I don’t think we’re finished digging there yet,” Burnham said. “We’ll roll the dice and hopefully get a more complete skeleton.”
Melton is convinced that out of the 10 to 15 permits his Miles City office will issue to museums at Yale, in Denver or in St. Louis for paleontological explorations next summer, those folks will find something.
“I would expect this year, once the snow melts and things start eroding again, we’ll probably by the end of the season see some spectacular things come out.”