Featured creatures: Basilosaurus, Dorudon, Andrewsarchus, Embolotherium (the brontotheres), Apidium, Physogalaeus (the sharks).
Basilosaurus, as its name ("king lizard") indicates, was originally thought to be a giant sea serpent before it was identified as a whale.
Upon discovery, Dorudon was initially mistaken for a young Basilosaurus.
"Whale Killer" refers to the modern killer whale, a vicious predator like Basilosaurus. It even hunts great white sharks from time to time.
The Apidium are a recolored and slightly tweaked version of the Godinotia animation from the previous episode.