Parasites are organisms that live on or in another organism, called the host, and benefit from it at the host's expense.
Parasites can cause various diseases and disorders in humans and animals. But how long have parasites been around, and what can they tell us about the past?
A new study by researchers from Mahasarakham University in Thailand and other institutions has shed some light on these questions by discovering evidence of ancient parasites in a fossilized feces, also known as a coprolite.
The study was published in the journal PLOS ONE on August 9th.
How did the researchers find the parasites?
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The researchers collected and analyzed a coprolite from the Huai Hin Lat Formation in Thailand, which dates back to the Late Triassic period, more than 200 million years ago.
This was a time when dinosaurs and other reptiles dominated the land, while fish and amphibians thrived in the water.
The coprolite was cylindrical in shape and more than seven centimeters long.
Based on its shape and contents, the researchers suggested that it was likely produced by a phytosaur, a crocodile-like predator that lived in freshwater habitats.
Phytosaurs were among the top predators of their time, feeding on fish, amphibians, and other reptiles.
The researchers used microscopic techniques to examine thin sections of the coprolite. They found six small, round, organic structures that ranged from 50 to 150 micrometers in length.
One of these structures was identified as an egg of a parasitic nematode worm, belonging to the order Ascaridida.
The other five structures were either eggs of other worm species or cysts of protozoan parasites.
This is the first record of parasites in a terrestrial vertebrate host from the Late Triassic of Asia, and one of the few examples of nematode eggs preserved in coprolites from the Mesozoic era.
The discovery also showed that multi-parasite infection was common and had already diversified by the Late Triassic, as per Phys.org.
The discovery of ancient parasites in a coprolite has several implications for our understanding of the evolution and ecology of parasites and their hosts. For example:
It revealed that parasites have a long and complex history that spans millions of years and involves various groups of animals.
It indicated that parasites may have co-evolved with their hosts, adapting to their physiology, behavior, and environment.
It suggested that parasites may have influenced the health and survival of their hosts, affecting their growth, reproduction, and immunity.
It provided a rare glimpse into the diet and lifestyle of an extinct animal that was infected by multiple parasites.
The discovery also highlighted the importance and potential of coprolites as a source of paleontological information, as per Popular Science.
Coprolites can preserve traces of various organisms that are otherwise difficult to find in fossils, such as soft tissues, DNA, and parasites. They can also reveal details about the food web and food chain of ancient ecosystems.
The researchers hoped that their discovery will inspire more research on ancient parasites and their hosts, as well as on coprolites and their contents, and that their discovery will contribute to a better appreciation of the diversity and significance of parasites in nature.
