Fossilized feces, known as coprolites, are a unique type of trace fossil that offer direct evidence of ancient life and behavior. Unlike skeletal remains, which reveal an animal’s morphology, coprolites provide a snapshot of an organism’s final meals, internal health, and even social habits. These stone archives are a fundamental resource for paleontologists, helping reconstruct prehistoric food webs and ecosystems. The study of coprolites offers a detailed look at the daily activities and environmental context of long-extinct animals.
Defining and Identifying Coprolites
The first step for scientists is to definitively distinguish coprolites from other fossil materials, such as gastroliths (stomach stones) or inorganic concretions, which can be easily confused. Coprolites often exhibit a diverse range of shapes, sizes, and surface textures, sometimes including spiral or annular markings that reflect the structure of the animal’s intestinal tract. They may also have distinct compaction folds or pinch marks, depending on the producer’s anatomy.
Geological context is important, as coprolites are found in sedimentary rock layers alongside other fossils like bones, teeth, or plants. The high concentration of calcium phosphate, a mineral found in abundance in bone and feces, is a chemical indicator that helps confirm a fecal origin, especially for carnivore droppings. Initial analysis involves preparing thin sections, where an ultra-thin slice is cut and mounted on a glass slide for microscopic examination. This allows researchers to look for mineralized structures, such as finely preserved muscle tissue or bone fragments, found within the fecal matrix.
Decoding Ancient Diets and Food Sources
Coprolites provide the most direct evidence of what an extinct animal ate. Scientists analyze the undigested or partially digested food residue found within the fossilized mass. Macroscopic inclusions, visible to the naked eye, often include bone fragments, fish scales, teeth, mollusc shells, or pieces of insect exoskeleton, suggesting a carnivorous or omnivorous diet.
Microscopic analysis reveals smaller components such as pollen grains, phytoliths (plant silica bodies), seeds, or fungal spores, indicative of a herbivorous diet. The presence of bone fragments or specific types of plant matter helps determine if an animal was a primary consumer, a predator, or a specialized insectivore. Advanced chemical techniques, like stable isotope analysis, confirm food sources by analyzing proteins, lipids, and trace elements preserved in the coprolite matrix. This analysis allows for the reconstruction of ancient food webs and clarifies the trophic level of the animal.
Insights into Health and Disease
Beyond diet, coprolites serve as a remarkable archive of the internal health and disease burden of ancient animal populations. They are a primary source for identifying parasitic infections, as the eggs or cysts of helminths and protozoans are often preserved inside the fossilized material. The identification of multiple parasite types in a single specimen suggests that such infections were common in prehistoric ecosystems.
The presence of specific parasites provides clues about environmental conditions or the animal’s interaction with intermediate hosts. For instance, a parasite requiring a fish host implies the animal’s proximity to water sources or the consumption of aquatic prey. Techniques like ancient DNA (aDNA) analysis can identify pathogens or confirm the host species that produced the coprolite, offering a window into paleomicrobiology and the evolution of disease.
Behavioral and Ecological Reconstruction
The way coprolites are deposited in the environment can reveal behavioral patterns beyond simply what an animal ate. The discovery of dense, localized concentrations of coprolites, known as communal latrines, suggests social or territorial behavior. This behavior, common in modern megaherbivores like rhinos, has been documented in Triassic dicynodonts, indicating a form of gregariousness or herd structure.
The physical location of these deposits offers insights into an animal’s preferred habitat, migration routes, or territorial boundaries. By identifying the specific plants and animals found within the coprolites, scientists can reconstruct the paleoclimate and ecosystem, confirming which organisms coexisted.