whippo

noun2

1. •
   (informal) Any member of the suborder Whippomorpha, including whales and hippopotamuses.

   • The whippo lineage may have developed a watery lifestyle even before the hippos and whale branches diverged. — 1999
2. •
   (informal) A hypothetical common ancestor between whales and hippopotamuses.

   • As an example of this confusion, transitional forms are not to be sought between equally derived living whales and their closest living relatives, the hippos. We do not search for "whippos." — 2012