• Posted August 10, 2023

Parasites Plagued Ancient Reptiles 200 Million Years Ago

Scientists have found evidence of ancient parasites preserved in the dung of an aquatic predator from more than 200 million years ago.

The ancient predator -- believed to be an extinct crocodile-like reptile called a phytosaur -- was infected with nematodes and multiple other parasite species.

While parasites are a common and important part of ecosystems, ancient parasites are hard to study because they often inhabited the soft tissues of their host, which rarely preserve as fossils, according to researchers.

It is, however, possible to find traces of parasites within fossilized feces, or coprolite.

In this study, published Aug. 9 in the journal PLOS ONE, researchers describe evidence of parasites in a Late Triassic coprolite from the Huai Hin Lat Formation of Thailand, which is over 200 million years old.

Led by Thanit Nonsrirach of Mahasarakham University in Thailand, team members studied the coprolite, which is cylindrical in shape and more than 7 centimeters (nearly 3 inches) long.

Microscopic analysis of thin sections of the coprolite found six round, organic structures between 50 and 150 micrometers long.

One was oval-shaped and had a thick shell. Researchers identified it as the egg of a parasitic nematode worm. The others appear to be additional worm eggs or some sort of protozoan cyst.

This is the first record of parasites in a terrestrial vertebrate host from the Late Triassic of Asia, the researchers said in a journal news release.

It's a rare glimpse into the life of an ancient animal that appeared to have been infected by multiple parasites.

The discovery, which adds to a few known examples of nematode eggs preserved in the coprolites of Mesozoic animals, is considered a significant contribution to scientific understanding of the distribution and ecology of these parasites.

More information

The U.S. Centers for Disease Control and Prevention has more on parasites.

SOURCE: PLOS ONE, news release, Aug. 9, 2023