he was filter feeding as usual, but a chunk of shark got in the middle of a plankton cloud that titan was feeding on
after he got to the chunk, he suddenly got hooked (get it because fish)
then he started scavenging, leaving his school of fellow titanichthys
after a while, he got sick of scavenging, plus there was barely any carrion left
so he started going after small sea scorpions
he loved the excitement he got from chasing down prey, this was was way better than his days of filter feeding
after sea scorpions, he moved on to large fish
then to sharks
and finally, to other placoderms
and the grand devonian feast begins