Alexis is wearing the Shock Collar this morning!

Today's question: When Lewis and Clark began their expedition west, President Thomas Jefferson wanted them to explore the new land, but he also had another thing on his mind...Jefferson was obsessed with animals and he held out hope that one particular creature still existed in unexplored territory.

He had heard rumors that these animals might be living free and he wanted proof so he could claim that his country's animal life was superior to that of other countries. Lewis and Clark never found any evidence of this animal, but Jefferson remained convinced they were out there even until his death. What animal was it?