Tapeworm Eggs Found in Ancient Shark Feces

A cluster of tapeworm eggs have been discovered in 270 million-year-old fossilized shark feces, a new study says.

The find suggests that the intestinal parasites, common in vertebrates, are much older than previously thought. It could also potentially sow the seeds for Hollywood’s next monster movie: Sharkworm: Escape from the Past.

Shark poop picture
A piece of 270-million-year-old fossilized shark feces. Photograph courtesy PLoS ONE.

“This discovery shows that the fossil record of vertebrate intestinal parasites is much older than was previously known and occurred at least 270-300 million years ago,” according to the study, which was published January 30 in the journal PLoS ONE. (See Feces, Bite Marks Flesh Out Giant Dino-Eating Crocs.”)

Coprolites—the tidy scientific term for fossilized feces—are extremely useful in paleontological research because they provide evidence of an organism’s diet and behavior and, in this case, of which parasites it may have hosted. (Related: “Fossil Feces Explained.”)

Those ancient parasites are the forebears of the intestinal invaders that still turn stomachs and haunt digestive tracts today, including cestodes, better known as tapeworms.

Pesky Parasites

While it’s not unusual to find fossilized parasitic remains, the older the sample material, the less likely it becomes. For instance, such finds from the Mesozoic and Paleozoic periods are exceedingly rare and difficult to document. (See a prehistoric time line.)

For the recent study, scientists examined 500 samples of the Paleozoic shark feces in question, and only one contained the golden ticket—aka tapeworm eggs.

Tapeworm egg picture
A close-up of tapeworm eggs discovered in the coprolite. Photograph courtesy PLoS ONE.

The upshot of all this is that parasitism may have a longer and more glorious history than anyone realized.

“This is the earliest fossil record of tapeworm parasitism of vertebrates and establishes a timeline for the evolution of cestodes,” the study said. “The fossil parasite eggs presented here corroborate the theory that parasitism was present since the advent of life.”

Evidence, in other words, that the pesky parasites have been with us—and in us—vertebrates for a gut-wrenchingly long time.

Stefan Sirucek is a writer, journalist, and map enthusiast. His work has appeared in the Huffington Post and the Wall Street Journal.

Stefan Sirucek is a writer and journalist who reports from both sides of the Atlantic. He's written for the Huffington Post and Wall Street Journal. Follow him on Twitter at @sirstefan.
  • Deanna

    How do you find fossilized feces of fish? Wouldn’t it be highly prone to dissolving before it could mineralize? Mind boggling.

  • Angela Berger

    This is fascinating!

  • Bichfj

    I’m sure that Barney Rubble and Fred Flintstone would discard the poop from any fish they caught and cleaned. That would be the fish coprolite.

    Or you could ask one of the creationists. And it would be a lot fresher too.

  • Hans

    Gosh, I need to go on the tapework diet…

  • Steven

    For anyone wondering the same as Deanna there is a link ‘hidden’ in plain view, just look for (Related: “Fossil Feces Explained.”) lol :]

  • Amy

    Um….that’s just weird.

About the Blog

Researchers, conservationists, and others share stories, insights and ideas about Our Changing Planet, Wildlife & Wild Spaces, and The Human Journey. More than 50,000 comments have been added to 10,000 posts. Explore the list alongside to dive deeper into some of the most popular categories of the National Geographic Society’s conversation platform Voices.

Opinions are those of the blogger and/or the blogger’s organization, and not necessarily those of the National Geographic Society. Posters of blogs and comments are required to observe National Geographic’s community rules and other terms of service.

Voices director: David Braun (dbraun@ngs.org)

Social Media