Coprolite
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Coprolites are fossilized feces, or animal dung. They form an important class of objects studied in the field of paleontology.
The name is derived from the Greek words kopros meaning "dung" and lithos meaning "stone".
Coprolites are also trace fossils and vary in size from the small fecal pellets of a sea-snail to the large droppings of crocodiles, dinosaurs, or mammals. Typical sizes vary from less than 5 mm (0.2") to 5 cm (2"), although they may exceed 30 cm (12") in length. There is a large variety of shapes: cigar-shaped, lens-shaped, kidney-shaped, cone-shaped, round, oval, cylindrical, or spiral-shaped, depending upon the type of animal which produced them, although as with other trace fossils, the specific animal is usually not known.
The recognition of coprolites is aided by their structural patterns, such as spiral or annular markings, their content, such as undigested food fragments, and also by associated fossil remains. The smallest coprolites are often difficult to distinguish from inorganic pellets or from eggs. Most coprolites are composed chiefly of calcium phosphate, along with minor quantities of organic matter. By analysing coprolites sometimes the diet of the animal which produced them may be determined.
Coprolites have been recorded in deposits ranging in age from the Ordovician period to recent times and are found worldwide. Some of them are useful as index fossils, such as 'Favreina' from the Jurassic period of Haute-Savoie in France.
Some marine deposits contain a high proportion of fecal remains, however, animal excrement is easily fragmented and destroyed and so usually has little chance of becoming fossilized.