Did Jaws Really Eat His Greens, Too?

What if I told you that hammerhead sharks used to eat algae and plants? You’d probably laugh and say, “No way!” And, you wouldn’t be alone in your disbelief.

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Great Hammerhead Shark spotted in a marine sanctuary. (sanctuaries.noaa.gov)

But in 2014, scientists discovered a new set of fossils belonging to what is now the earliest record of a plant-eating marine reptile. And it looks strangely similar to a hammerhead shark.

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An artist’s rendering of the plant-eating marine animal as it uses its jaw to shovel and scrape algae and plants off the sea floor. (Illustration: Y. Chen, Institute of Vertebrate Paleontology and Paleoanthropology)

The fossils were discovered in what is now southern China and predate the earliest known plant-eating marine animal by 8 million years! When it was first discovered, scientists thought it had flamingo-like beak, but thanks to the new fossils, scientists were puzzled to discover a hammer-shaped jaw.

Even more interesting is its strange dental arrangement. Around the outer edge, the hammerhead has peg-like teeth and further inside the mouth there are needle-like teeth. Scientists hypothesize that this combination of teeth actually helped this reptile eat plants. The peg-like teeth allowed for scraping plants off the ocean floor while the needle-like teeth acted as a sieve to trap the plant and algae material while letting the water flow out – similar to how whales use baleen to feed.

Scientists have been puzzled by this reptile’s anatomy, even granting it a Latin name that means ‘uniquely strangely toothed.’ Thanks to these new fossils (and Play-dough), though, we have a better understanding of their strange teeth and jaw.

Scientists sought to understand the jaw and tooth morphology of this plant-eating, sea-dwelling animal better and relied on our trusty pal, Play-dough, and toothpicks to help them roughly model the anatomy. (Copyright Olivier Rieppel, The Field Museum)

These fossils help tell a bigger story, though. Approximately, 242 million years ago, the world’s largest mass extinction event, the Permian-Triassic mass extinction (PTME), wiped out nearly all life on earth, including 96% of marine species.

But how did the remaining animals respond to such a dramatic change in the composition of life on earth?

This extinction event actually allowed for the emergence of several entirely new groups of organisms, including marine reptiles. The existence of these unique creatures tells us that life recovered and evolved quickly in the wake of the PTME.

So while these sea-dwelling reptiles certainly weren’t the Jaws of their time, their novel jaws may have given you cause to swim the other direction. Especially if you haven’t washed between your toes in awhile!

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