Did the mosasaur, a reptile that moved from land to sea 92 million years ago, end up wiping out the ginsu shark? A recent article in the journal Paleobiology traces the evolution of the mosasaur from a three foot shallow water swimming lizard to a 56 foot large-toothed ocean-going predator over the 27 million years it lived in the oceans.
The oldest swimming ancestor of the mosasaur, was the Dallasaurus, a reptile that was about three feet long and swam like an eel, moving side to side. This type of motivation is useful when ambushing prey because it provides a burst of speed over a short period of time. But in the open ocean, it's more useful to swim long distances over sustained periods of time in search of prey.
Over the course of several million years, the Dallasaurus evolved, and the tail changed, with the vertebrae shortening making the tail more powerful. The hands and feet also evolved to become more like paddles for more efficient propulsion.
The Dallasaurus packed on a few pounds and took on some length, ending up at 56 feet long and probably at the top of the food chain in the Cretaceous period.
At about the same time that the mosasaur evolved to this state, there was another top predator, the ginsu shark (and yes, it was named after the steak knives featured on late-night TV). The 22-foot predator seems to have fed by using its teeth to slice victims into bite-size chunks, including slicing directly through vertebrae while leaving no serrated marks.
As the mosasaur evolved to its full size, the ginsu shark population took a nose dive. Some experts believe that the mosasaur became such a fearsome predator that it feasted on young ginsu sharks and decimated the shark's population to the point of extinction.
