The Yellowstone Creature crossword solutions are ELK and MOOSE. ELK, also known as Wapiti, are one of the largest species in the deer family and are native to North America, Europe, and Asia. MOOSE are the largest species in the deer family and are found in North America, Europe, and Asia. They are easily recognizable by their long, humped back and large antlers. Both ELK and MOOSE can be found in Yellowstone National Park.