Scientists at Northwestern University in Xi'an, China have studied the earliest parasite-host relationship using beautifully preserved 515-million-year-old fossils from southern China. We are talking about the brachiopods Neobolus wulongqingensis.
Research has shown that chitinous airways on the valves of fossil brachiopod shells once harbored parasitic worms. A clear negative effect on the host is evident, since Neobolus without parasites grew larger than those who had them. It is difficult to determine what type the worms were, but it was possible to find out that they were with the owner all their lives and were kleptoparasites - they stole food from the owner before he swallowed it.
Extant shell of Neobolus wulongqingensis
Scientists were able to establish other facts of parasitism based on ancient fossils. Spiral bacteria, almost identical to those that cause Lyme disease, were found in a 15 million year old fossil mite buried in amber. "Language worms" (Pentastomida) live today, but the history of their genus goes back hundreds of millions of years. The research team even has evidence of ancient lice damaging dinosaur feathers.
The age of these fossil parasites coincides with the so-called Cambrian explosion. This event began about 540 million years ago during the Cambrian. It was a time of rapid evolutionary change when the first animals with eyes, organs and limbs appeared. These changes have had a noticeable effect on the interaction of organisms with each other. It is believed that active predation began at this particular time. And parasitism, apparently, is no exception.