Fossilised tapeworm eggs discovered in 270-million-year-old shark feces suggest that intestinal parasites in vertebrates are much older than previously known, according to researchers. Remains of such parasites in vertebrates from this era are rare — of 500 samples examined, only one revealed the tapeworm eggs.
This particular discovery helps establish a timeline for the evolution of present-day parasitic tapeworms that occur in foods like pork, fish and beef. The study was carried out by Paula Dentzien-Dias and colleagues from the Federal University of Rio Grande, Brazil.
The fossilised eggs were found in a cluster very similar to those laid by modern tapeworms. Some of them are un-hatched and one contains what appears to be a developing larva. “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.
The fossil described in this study is from Middle-Late Permian times, a period followed by the largest mass extinction known, when nearly 90 percent of marine species and 70% of terrestrial species died out.
The research has been published in the open access journal Plos One.