Small Tyrannosaur Is Confirmed
A decades-old debate about whether a small tyrannosaur Nanotyrannus was its own species or simply a growing, teenage Tyrannosaurus rex has been settled by a fossil found in Montanna.
The discovery “rewrites decades of research on Earth’s most famous predator,” said study co-author Lindsay Zanno, a paleontologist at North Carolina State University and North Carolina Museum of Natural Sciences.
The skeleton was originally found nearly 20 years ago and is part of the “Dueling Dinosaurs” fossils. Those fossils are between 66 and 67 million years old and consist of the newly classified Nanotyrannus and a Triceratops, possibly locked in a battle when they died.
The study was published in Nature earlier this fall and was co-authored by James Napoli, an anatomist at Stony Brook University in New York. The pair were able to study the growth rings in the bones, as well as other aspects of the dinosaur’s ANATOMY, to determine that the Dueling Dinosaur Nanotyrranus fossil was about 20 years old and almost fully grown, meaning it was not simply a young T. rex.
The Nanotyrannus weighed in at around 1,500 pounds, while an adult T. rex could weigh up to 18,000 pounds. It also measured just under 20 feet, which is half the size of an adult T. rex. The Nanotyrranus was swift and agile, and had other distinguishing features, including more teeth and larger hands and claws.
While other scientists largely agree with Zanno and Napoli that Nanotyrannus is a distinct species, there is less agreement about the relationship. The study’s authors argue that Nanotyrannus is a distant cousin of the T. rex, but some scientists believe they’re actually sister species and more fossils would be needed to confirm the relationship.
“The overarching mic drop of this paper is that Nanotyrannus is real, its own distinct tyrannosaur species, and that necessitates a fundamental reassessment of tyrannosaur classification and evolution,” said Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland.
