Why, in order for a paleontologist to win the internets, all he or she needs to do is come up with a new and interesting paleo-fight. If it includes a badass new species, that's just gravy, man.
This monster whale is named Leviathan melvillae, you know, after that sweet Mastodon album and that monster whale writer guy. Notice how the illustrator expertly drew old Leviathan as a cross between a sperm whale and an orca and composed the piece to echo the Jaws poster. It's a great illustration, but Dr. Christian de Muizon, speaking to the BBC, hints at what might make a BETTER illustration :
"And it's interesting to note that at the same time in the same waters was another monster, which was a giant shark about 15m long. It's possible that they might have fought each other".
Not to put words in the guy's mouth, but he's clearly referring to Carcharodon megalodon, the giant great white of the ancient seas. It's definitely a demonstration of the ___ vs. ___ formula of internet animal interaction. It's also a manifestation of our mammals vs. cold-blooded suckers bias. Finally, it is based on behavior that we see today in orcas:
(Interesting fact I just learned about megalodon from wikipedia: in Renaissance times the fossilized teeth of sharks were thought to be the tips of dragon or serpent tongues, were known as "tongue stones," and were used as a remedy for or amulet of immunity to poisons.)
Anyway, here's a little Nature video about it. Please notice the youtube comments. After you get through the firstie and firstie hate, the fifth comment mentions megalodon. It's on the tip of the internet tongue I tell ya!