One of these things is not like the others
Please go to the Question #20 post if you haven't had a chance work on this one yet, since the text below contains the solution.
The coelacanth is a type of fish which was believed to be extinct (for over 65 million years!), but was discovered in 1938 to still be around. The other three animals listed aren't still around -- they're actually extinct. So as the only living animal on the list, the coelacanth does not belong.