MEANING: Polar bear lizard
PERIOD: Late Cretaceous
CONTINENT: North America
Nanuqsaurus is a tyrannosaurid theropod from Alaska. 70 million years ago, Alaska experienced cold weather and extreme changes in daylight during the year. Prey availability likely would have increased during the summer, then declined in the dark winter, leaving predators with little to eat. In its initial description, Nanuqsaurus was estimated to have been 5–6 m long and 500–900 kg in weight. This diminutive size was postulated as being an adaptation to its high-latitude habitat. However, later studies suggested that its supposed small size was unfounded, and that it was likely similar in size to other North American tyrannosaurids - as much as 9 m in length.
Nanuqsaurus is from the Cretaceous. The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.
The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct flora and fauna, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.
Nanuqsaurus is a tyrannosaurid. Tyrannosauridae is a family of theropod dinosaurs known for often being the largest predators in their ecosystems, at the top of the food chain. They lived near the end of the Cretaceous Period in North America and Asia. Tyrannosaurids were bipedal carnivores with massive skulls and large teeth. Their long legs were proportioned for fast movement, but their arms were very small, and only had two functional digits.
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