Fossilized remnants of dinosaur droppings offer a direct, tangible link to the daily lives and diets of these ancient creatures. Unlike immense skeletons that reveal size and shape, these rare specimens capture a unique part of prehistoric life that has long fascinated researchers and the public. Preserved over millions of years, they provide physical evidence detailing the composition of the dinosaur’s last meal. This allows scientists to piece together a more complete picture of Mesozoic ecosystems.
Defining Coprolites and Fossilization
Fossilized feces are scientifically known as coprolites, derived from the Greek words kopros (dung) and lithos (stone). Paleontologists classify them as trace fossils, recording the behavior and presence of an animal rather than the animal’s body itself. Preservation is rare because the organic waste is highly susceptible to decay and scavenging shortly after deposition.
For feces to become a coprolite, the organic matter must be mineralized quickly, typically by rapid burial under sediment. Mineral-rich groundwater percolates through the buried waste, gradually replacing the original organic material with inorganic compounds. This process often involves calcium phosphate deposition, resulting in a rock displaying colors based on the specific mineral composition.
Appearance Differences Between Carnivore and Herbivore Feces
The physical appearance of a coprolite offers immediate clues about the dinosaur’s diet. Fossil size varies greatly; some of the largest, likely from massive sauropods, reach up to 40 centimeters in diameter. The shape is determined by the internal structure of the animal’s lower intestine, resulting in forms that range from amorphous masses to distinct, elongated cylinders.
Carnivore Coprolites
Coprolites from carnivores tend to be dense and hard due to their high mineral content. These fossils often have an elongated or cylindrical shape, sometimes exhibiting a smooth, spiral pattern on the exterior surface. This spiral morphology reflects the coiled structure of the predator’s intestinal tract.
The surface frequently shows a rough texture where partially digested bone fragments or tooth shards protrude. Examination of a cross-section reveals a highly compacted composition, sometimes consisting of up to 50% pulverized bone. This high concentration of skeletal material makes carnivore coprolites more likely to fossilize and survive in the geological record compared to those from herbivores.
Herbivore Coprolites
Feces from herbivores generally present as large, rounded, or amorphous masses. These samples are less dense and more porous than carnivorous counterparts because they contain a lower concentration of durable mineral components. Preservation is less common because the high volume of soft plant material rapidly decomposes.
When found, herbivore coprolites feature a fibrous texture from the inclusion of undigested plant matter, such as bark, seeds, and leaf fragments. Unlike the smooth, dense structure of carnivore samples, the surface appears rough and fibrous. In some cases, these coprolites contain gastroliths—small, smooth stones ingested to help grind up tough plant material—further confirming the herbivorous diet.
Information Revealed by Internal Contents
Beyond external shape and texture, the internal contents of coprolites provide specific data on the dinosaur’s ecology and biology. Paleontologists use advanced imaging techniques, such as synchrotron scanning, to generate detailed three-dimensional visualizations of the fossil’s interior without destroying the specimen. This method allows researchers to identify specific micro-inclusions invisible to the naked eye.
The contents reveal detailed information about the dinosaur’s life and environment:
- The identification of specific plant spores, pollen grains, or insect parts reveals the exact species consumed, allowing scientists to map the ancient distribution of different plant species.
- The discovery of charcoal within some sauropod coprolites suggests these herbivores may have intentionally ingested burnt wood to aid in detoxification or digestion.
- Fossilized eggs or cysts of ancient parasites offer insights into the dinosaur’s health and the prehistoric disease landscape.
- The size and degree of fragmentation of bone or plant material informs researchers about the animal’s digestive processes.
These forensic details transform the fossilized waste into a time capsule of biological and environmental information.