Space & Innovation

What Did Sharks Look Like 450 Million Years Ago?

Sharks have survived through 5 mass extinctions! Find out how they've evolved throughout millions of years.

"Here's some advice I wish I got when I was your age: Live every week like it's Shark Week."

This sage advice was offered by Tracy Jordan on the late, great 30 Rock, and it's an important reminder for all of us. Shark Week is fast approaching once again and the world trembles with anticipation.

In today's DNews report, we provide an appetizer of sorts -- a quick primer on the evolutionary processes that resulted in everyone's favorite superpredator.

Sharks have been around on planet Earth for about 450 million years, at least, which makes them 200 million years older than the first dinosaurs. Those numbers suggest that sharks are one of the most adaptive, resilient and successful species ever to emerge from the primordial soup.

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Evidence of the earliest sharks come from a handful of scales found in Colorado and Siberia. Because sharks have skeletons made of cartilage, not bone, they don't fossilize particularly well. So we're not really sure what the very sharks looked like. But we do know that, over the epochs, sharks have evolved into a large variety of shapes and sizes.

Scientists have discovered evidence of sharks with two-pronged teeth, sharks shaped like eels, and even adorable li'l mini-sharks less than an inch in length. Alas, around 250 million years ago most of these shark variations died out -- along with 99 percent of all marine life -- in the colossal bummer known as the Permian-Triassic extinction event.

But sharks are tough. Archaeobiologists now believe that sharks may have survived as many as five major extinction events. Modern sharks, as we know and love them today, emerged in the Jurassic period about 200 million years ago.

Unfortunately, their numbers are dwindling fast, largely due to the activities of our own lethal species. For more information on that, check out this report and, of course, tune into Shark Week -- kicking off Sunday, June 26.

-- Glenn McDonald

Learn More:

BBC: Spiral-toothed fossil mystery solved

ScienceDaily: Great White Shark Evolution Debate

Tech Times: Sharks Have Different Personalities Just Like Humans: Study