The Call of the Sea: Mammalian Evolutionary transitions back to the sea

According to a new study by Maria Chikina and Nathan Clark evidence has shown that during main evolutionary events land animals made their way back into the sea. One of these marine animals is the modern day mannatee. The call for these creatures to go back to the sea stemmed from certain genes that had evolved charactistics that preferred a marine environment. The evolved genes had led to new functions for skin and connective tissue formation as well as a diminished sense of taste and smell. The study also found the specific genes responsible for such function. A gene coding for a lung surface protein evolved to increase lung capacity and diving depths.  These land creatures that went back to the sea evolved and adapted to their environment efficiently and quickly.

https://www.sciencedaily.com/releases/2016/06/160622164320.htm
http://www.manatee-world.com/manatee-evolution/