The term 'Extinct Creature' can be summarized by two crossword solutions: DODO (4 letters) and Mastodon (8 letters). The DODO was a flightless bird native to the island of Mauritius in the Indian Ocean. It became extinct in the late 17th century due to human activity. The Mastodon was a large, elephant-like mammal that lived during the Pleistocene epoch. It went extinct around 10, 000 years ago, likely due to climate change.