Paleoparasitology
Paleoparasitology (or "palaeoparasitology") is the study of parasites from the past, and their interactions with hosts and vectors; it is a subfield of paleontology, the study of living organisms from the past. Some authors define this term more narrowly, as "Paleoparasitology is the study of parasites in archaeological material." (p. 103) K.J. Reinhard suggests that the term "archaeoparasitology" be applied to "... all parasitological remains excavated from archaeological contexts ... derived from human activity" and that "the term 'paleoparasitology' be applied to studies of nonhuman, paleontological material." (p. 233)  This article follows Reinhard's suggestion and discusses the protozoan and animal parasites of non-human animals and plants from the past, while those from humans and our hominid ancestors are covered in archaeoparasitology. Sources of material

The primary sources of paleoparasitological material include mummified tissues, coprolites (fossilised dung) from mammals or dinosaurs, fossils, and amber inclusions. Hair, skins, nematode larvae found embedded in animal coprolites, and a mite caught in amber in the process of apparently feeding on a spider. In 2023, nematode eggs and possibly protozoan cysts were found in the Late Triassic coprolite of phytosaur. Some holes in the mandibles of several specimens of Tyrannosaurus may have been caused by Trichomonas-like parasites. Fossil organisms which are related to present-day parasites often possess the morphological features associated with a parasitic lifestyle, such as blood-feeding mouthparts. So fossil ticks and hematophagous insects are generally assumed to be ectoparasites, even when their remains are found in the absence of a host. The ancient flea Saurophthirus found in Early Cretaceous deposits had a sucking proboscis and a stretching abdomen, which indicates the parasitic lifestyle of this insect. The presence of structures resembling leaf miner trails in leaf fossils provide indirect evidence of parasitism, even if remains of the parasite are not recovered. The dramatic tissue aberrations seen in present-day plant galls and gall-like structures in some invertebrates are direct physiological reactions to the presence of either metazoan parasites or microbial pathogens. Similar structures seen in fossil plant and invertebrate remains are often interpreted as evidence of paleoparasitism. Host-parasite interactions today are often exploited by other species, and similar examples have been found in the fossil record of plant galls and leaf mines. For example, there are species of wasps, called inquilines, which are unable to induce their own plant galls, so they simply take up residence in the galls that are made by other wasps. Another example is the predation of plant galls or leaf mines, to eat the trapped insect larva inside the gall or mine. Knowledge gained from ancient animal and plant parasites

Studies of parasite remains and traces from the past have yielded a vast catalog of ancient host-parasite associations. Genetic sequence data obtained directly from ancient animal parasites, and inferences of past relationships based on genetic sequences of existing parasite groups are also being applied to paleoparasitological questions. Data obtained by all of these methods are constantly improving our understanding of the origin and evolution of the parasites themselves and their vectors, and of the host-parasite and vector-parasite associations. In some cases, presumed host-parasite relationships of the past seem quite different from those known in the present, such as a fly which appears to be a parasite of a mite

Paleoparasitological studies have also provided insight into questions outside the realm of parasitology. Examples include the migration and phylogeography of marine mammal hosts, the identity of domestic animal bones based on the known hosts of parasite remains found at the site, and the possible role of climatic changes on animal host genetic diversity. References

Parasitology
Parasitology