It’s Official – Osedax Worms Existed 100 Million Years Ago, Feeding on Mosasaurs, Ichthyosaurs, and Plesiosaurs

Bone-eating worms might sound like something straight out of a sci-fi horror movie, but they’re 100% real—and they’ve been quietly living at the bottom of the ocean for over 100 million years. These bizarre creatures, known as Osedax, don’t munch on leaves or hunt prey. Nope. They live off bones. And not just any bones—massive ones, like whale skeletons or even the remains of ancient sea reptiles. Intrigued? Let’s cut into this strange story from the ocean’s depths.

Purpose

So, what do Osedax worms actually do? Picture this: a whale dies, sinks to the sea floor, and becomes a buffet for deep-sea organisms. That’s when Osedax worms show up. They don’t have mouths or teeth like typical worms. Instead, they drill into bones using root-like structures and rely on bacteria inside their bodies to break down and absorb the nutrients.

Think of them as nature’s silent recyclers, cleaning up the deep ocean floor by breaking down bones that would otherwise sit untouched for decades.

History

Now, here’s where things get really interesting. Scientists from University College London and the Natural History Museum in the UK wondered just how long these worms had been around. Using CT scans—like the ones used in hospitals—they scanned more than 130 marine fossils from the time of the dinosaurs.

They found six with tiny tunnels that matched the exact patterns Osedax worms leave behind today. That means these worms were alive and well over 100 million years ago, long before whales ever existed.

Evolution

So, what were they feeding on before whales roamed the seas? Fossils showed that these worms likely fed on the bones of giant marine reptiles like mosasaurs, plesiosaurs, and ichthyosaurs.

Even more fascinating, scientists found seven new types of ancient Osedax—called ichnospecies. These are species we know only by the traces they left behind, like burrows or marks in bone. Some of these ancient tunnel patterns were nearly identical to modern ones, showing these worms haven’t changed much over time.

That kind of evolutionary stability? It’s rare—and it proves these creatures were perfectly adapted to their lifestyle millions of years ago.

Discovery

To confirm the age of these fossils, the team studied the rock layers surrounding the bones. These layers dated back to the Cretaceous period. So yeah—Osedax worms were busy doing their thing at the same time dinosaurs walked the Earth. That’s a long time to keep a job.

Future

Even with these findings, there’s still a lot to uncover. Scientists think many more fossilized bones might hold Osedax burrows, just waiting to be discovered. They also want to study living Osedax species to compare their DNA with the fossil evidence.

Researcher Sarah Jamison-Todd pointed out that many modern and ancient bone burrows look eerily similar. This raises a big question: are we seeing the same worm species lasting millions of years, or did different worms evolve to do the same thing in the same way? That’s called convergent evolution, and figuring it out could tell us a lot about the worms’ role in the marine ecosystem.

Mystery

The ocean is still full of mysteries, and Osedax is one of the most fascinating. These worms may be tiny and hidden from view, but they play a big role in cleaning up the deep sea. They’ve been part of that ecosystem longer than whales, sharks, or even birds.

And while most of us will never see an Osedax in action, just knowing they exist adds another layer to the wonder of the ocean. From the bones of sea monsters to the skeletons of whales, Osedax has been quietly feasting away, keeping the cycle of life going on the ocean floor.

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