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.

Wildlife

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.