Coprolites: Fossilized Feces as Windows into Ancient Life

Coprolites (fossilized feces) are trace fossils that provide direct evidence of diet, physiology, behavior, and paleoenvironments of extinct organisms.

What Coprolites Reveal

• Dietary contents: Undigested bone fragments, fish scales, plant fibers, seeds, pollen, phytoliths → carnivory, herbivory, omnivory, specific prey/plant taxa.
• Digestive physiology: Degree of bone dissolution → stomach acidity, retention time; spiral valve impressions → shark/ray identification.
• Parasites: Helminth eggs, protozoan cysts → paleoparasitology, host-parasite coevolution.
• Gut microbiome proxies: Biomarkers (sterols, bile acids) in exceptionally preserved specimens.
• Taphonomy & environment: Mineralization mode (phosphate, carbonate, silica) → burial conditions, diagenesis.
• Behavior: Coprolite clusters → latrine behavior, denning; in nests/burrows → parental care, scavenging.

Identification Challenges

• Linking coprolite to producer: size, morphology, contents, stratigraphic association, nearby body fossils.
• Distinguishing from inorganic concretions: internal structure, organic geochemistry (GC-MS, FTIR).

Famous Examples

• Tyrannosaurus rex coprolite (Saskatchewan, 44 cm long) – crushed bone fragments → bone-crushing feeding.
• Early human coprolites (Paisley Caves, Oregon, ~14,000 BP) – DNA, protein residues → diet, migration timing.
• Permian shark coprolites – spiral valve impressions → earliest vertebrate intestinal morphology.

Analytical Techniques

• Thin-section petrography, SEM-EDS, micro-CT, stable isotopes, ancient DNA/protein analysis, lipid biomarkers.

Coprolites transform "waste" into high-resolution paleobiological data—revealing not just what ancient animals ate, but how they lived, digested, and interacted with their ecosystems.