Putting the laws of time and plausiblity aside, picture a battle between the megalodon (a prehistoric shark with a six-foot jaw span) and a giant squid (reported to be the size of a school bus). Who would win?
Oh, it's like Astronauts vs. Cavemen, all over again*. Personally, I think ninjas would win both fights.
*Sorry, I couldn't resist an Angel reference. That is one of the funniest scenes I think I've ever seen. That and Spike getting his arse kicked by Wee Little Puppet Man.
Sorry for the spamming, I'm bored.