It's a battle of shark versus shark dating back over a century

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This well-preserved fossil is the only intact partial skull ever found of a white shark that lived about 4.5 million years ago named Carcharodon hubbelli. CREDIT: Florida Museum of Natural History photo by Jeff Gage  View full size image

It's a battle of shark versus shark dating back over a century: Which species set the stage for modern great white sharks, the biggest carnivorous fish to roam the seas today?

In one corner are "megatooth" sharks, which include thelargest sharks ever to have lived. In the other is the smaller-but-plenty-toothy mako shark. Now, researchers say they have new evidence pointing to the mako shark as the great white's ancestor.  

Great white sharks (Carcharodon carcharias) are the biggest meat-eating shark in the world, with some reaching more than 20 feet (6 meters) long and weighing more than 5,000 pounds (2,250 kilograms). They hunt in more of the world's seas than any other sharks, ranging across the Atlantic, Pacific and Indian oceans, from the cold waters near the Antarctic to the tropical waters near the equator, cruising up to 43 miles per hour (70 kilometers per hour) in pursuit of prey.