Pint-Sized Tyrannosaur Stalked the Arctic
March 27, 2014
To scientists’ surprise, 70-million-year-old dinosaur fossils found some years ago in Alaska actually belonged to a previously unknown miniature cousin of Tyrannosaurus rex. This new species of pygmy dinosaur, Nanuqsaurus hoglundi, had a skull that was only 23 to 27 inches (60 to 70 centimeters) as an adult. The skull of an adult T. rex could be up to 60 inches (150 cm) long. (Note: The words pint-sized and pygmy here are relative. N. hoglundi was about the length of a polar bear, compared to which, students are pint-sized.)
The fossils—fragments of the top of the skull and jaw—were found in 2006 on Alaska’s North Slope, inland from Prudhoe Bay. The discoverers, who were involved in analyzing other fossils, shelved the fragments in a museum. When they recently examined the find, they discovered that the bones represented a new species of tyrannosaur. The tyrannosaurs, which lived during the late rank part of the Cretaceous Period, rank among the most frightening meat-eaters of their time. Tyrannosaurus rex, whose name means king of the tyrant lizards, is the most famous—but not the only—member of the genus.
Tyrannosaurs were fast, active carnivores. They roamed what are now western North America and east-central Asia. (c) Jan Sovak
A study of T. rex‘s mini cousin revealed that the part of N. hoglundi‘s brain devoted to smell was particularly enlarged. This suggests, the scientists said, that the dinosaur stalked its prey mainly by smell. A keen sense of smell would have been important in N. hoglundi‘s challenging environment. Although temperatures in what is now Alaska were much warmer 70 million years ago, the area still experienced long periods of darkness and challenging seasonal changes in the amount of available food. Scientists think the small size of this dinosaur predator was an adaption to its harsh environment. A smaller body is favored by natural selection because of the limited food sources available.
Additional articles in World Book:
- Tyrannosaurs rex: The Tyrant Still Reigns (a Special Report)
- What Has Caused Mass Extinctions? (a Special Report)
