I tamed mine with a baryonyx to kill the manta bodyguards. The time between the first and second feeding interval takes a while, so sit back and grab some coffee while you wait. Regular meat will do as after the second feeding, the interval is only about 10 seconds. Make sure you keep all Megalodons and other mantas away from it while taming. I absolutely love mine for alpha killing and bio toxin farming. Also they get a crap ton of hit points per level up, almost 400.
When you will try to tame one of these guys, you should have an aquatic creature first like an Ichythyosaur, because these basilosaurs keep moving away from you when they are hungry. When they are fed, they don't move away from that spotl also, bring a pike with you because there are alot of mantas following them.