Definition: Narwhal, also known as woolly mammoths, is a species of mammal that existed during the late Cretaceous period in North America. They were one of the largest land animals and are considered to be extinct due to their size and longevity. The exact age of these creatures remains controversial, with some scientists speculating that they may have lived until 10 million years ago or earlier, while others believe they lived for centuries. Narwhals had a thick layer