Tapeworm eggs were found inside 270-million-year-old shark poop.
Yes, you read that right, inside the feces of a shark aged at 270-million years. A team at Brazil’s Federal University of Rio Grande discovered the cluster of tapeworm eggs in the Rio do Rasto Formation from Paraná Basin, Mid to Late Permian and was collected in the municipality of São Gabriel, southern Brazil.
This strange discovery shows that tapeworm parasites are much older than what is previously known on record, which was dated to be 140 million years.
“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,” the authors write in their study.
The 93 fossilized eggs were found in a cluster very similar to those laid by today’s tapeworms. The eggs are about 150 microns long, or to put that into a visual perspective, it’s about one-and-a-half times the average width of a human hair. Most of the fossilized eggs were un-hatched. One contains what appears to be a developing larva, complete with the hooklets that it would have later used to attach to a host’s intestines.
The researchers write, “The eggs were found in a thin section of an elasmobranch coprolite. Most of the eggs are filled by pyrite and some have a special polar swelling (operculum), suggesting they are non-erupted eggs. One of the eggs contains a probable developing larva. The eggs are approximately 145–155 µm in length and 88–100 µm in width and vary little in size within the cluster.”
Tapeworms cling to the inner walls of the intestines of vertebrates in those with backbones such as fish, pigs, cows and even humans. When these parasites reach adulthood, they unleash their eggs via the feces of their hosts, explains Live Science.
When tapeworm proglottid is full of eggs, it breaks off in the stomach or intestine of the host and eventually passes out of the body with the feces. Normally, maturation of the eggs occurs only after this separation, so fully mature eggs occur only in the host gut and feces, the researchers report.
Of the 500 samples found at the same site in Brazil, only one contained tapeworm eggs. The researchers suggest that the area was once a freshwater pond, where fish were trapped during a dry spell.
“Luckily in one of them, we found the eggs,” researcher Paula Dentzien-Dias, a paleontologist at the Federal University of the Rio Grande in Brazil, told LiveScience. “The eggs were found in only one thin section.”
The researchers are now examining similar coprolites at the same outcrop. “We have to choose between 500 coprolites which ones will be cut,” Dentzien-Dias said.