Gastrointestinal Parasites of Ancient Nonhuman Vertebrates: Evidence from Coprolites and Other Materials

Fossilized feces offer a unique window on the evolutionary history of parasites by preserving propagules that were shed into ancient vertebrate feces for dispersal. Fossil gastrointestinal materials such as regurgitated pellets and gut contents can also preserve parasite propagules. The quality of preservation (morphological detail and percent of original parasites recovered) is largely controlled by the extent of age-related diagenetic alteration. Most Holocene parasites are preserved in desiccated substrates, and can be morphologically detailed and have sufficient recovery to facilitate epidemiological inferences. In contrast, pre-Holocene parasites are usually fossilized within lithified coprolites, and are rare and more difficult to find and identify. Nevertheless, protist, acanthocephalan, trematode, and nematode propagules have been recovered from Mesozoic coprolites, and cestode eggs have been documented in Paleozoic feces. These fossils provide fossil evidence for long evolutionary relationships between vertebrates and gastrointestinal parasites with complex life cycles.