Here is one thing I am having a hard time understanding about Christians?

Many claim not to believe in evolution, and believe that the animals on our planet have existed, unchanged since they first appeared on the planet, and were vegetarian. I look at crocodiles, cheetahs, snakes and great white sharks and it seems obvious to me that they eat meat. The way they evolved or were designed would suggest that either they are very efficient at what they do. Cheetah run 70 miles per hour because their main prey can run 60mph. You don't need to run 70mph to catch a carrot. The teeth and jaws of the great white shark are perfectly designed or evolved to rip chunks of flesh from other animals and fish, and although they could probably be equally adept at opening cans of pineapples, I just don't see that happening. What is the Christian take on todays carnivorous predators surviving on a solely vegetable diet in the not too distant past?