Beyond ichthyosaurs and cetaceans, carcharhinification (shark-like convergent evolution) also occurred in plesiosaurs, mosasaurs, certain teleost fish like barracuda, and even the extinct thalattosuchian crocodylomorphs.
Jurassic-Cretaceous marine crocodiles (like also ichthyosaurs and mosasaurs) looked like sharks, i.e. they depended mostly on their caudal fin for swimming.
On the other hand, there was no resemblance between sharks and plesiosaurs or pliosaurs. The latter swimmed using their lateral fins, somewhat like marine turtles and penguins, not like sharks. Also the dentition of plesiosaurs and pliosaurs had no similarity to sharks, so except for being big predators there were no resemblances between them.
