An international team of paleontologists studied fossils of brachiopods found in China. However, these fossils had signs of parasitism. This is the earliest evidence of parasitism known to humans, dating back more than half a billion years.
The oldest evidence of parasitism
First of all, let’s remember that brachiopods (Brachiopoda) are marine animals that experienced significant evolutionary success during the Paleozoic (from -541 to -252.2 Ma). In the fossil record there are about 12,000 species of brachiopods, but today only about 450 remain. One of these fossilized species discovered in Yunan province (China) was the subject of a study published in the journal Nature Communications on June 2, 2020.
The brachiopods of the species Neobolus wulongqingensis lived about 512 million years ago in the seabed, hooked by a long peduncle. After examining thousands of fossils of this species, the researchers observed in most cases the presence of a kind of tube embedded in the shells. According to the study leaders, this is a species of tubal parasite. This discovery simply obtained the oldest evidence of parasite-host relationship (parasitism) known to date.
Obviously, the researchers tried to demonstrate the veracity of their hypothesis. However, it seems that an argument along these lines was rather convincing. Indeed, the shells with traces of tubes were smaller than those without them. According to paleontologists, the parasites diverted part of the food from the brachiopods, which logically impacted their development. In other words, we are talking about a phenomenon called kleptoparasitism.
Remember that it is often complicated to document the cases of parasitism in the fossil record. Indeed, it is essential that researchers can observe fossils containing the two species – the parasite and the host – or at least a trace of these same two species. This difficulty is moreover very linked to the fact that the parasites are often microscopic organisms, of which the soft tissues do not keep much.
However, some researchers have an exceptional chance. In 2019, Chinese and American paleontologists indeed made an incredible discovery. There was talk of the presence of a dozen lice nymphs kept on two dinosaur feathers in two pieces of amber dating back about 100 million years!