Agatized Coprolite Specimen #103 Measures approx. 3 1/4" x 2 1/8" x 2" By formal definition, coprolites are the fossilization or preservation of the contents of the intestine and the excrement of organisms, or quite simply they are fossilized feces. Coprolites are quite rare because they tend to decay rapidly, but when they are found, they are most commonly found among sea organisms. Coprolites of fish and reptiles are especially common. Typically nodular or contorted in appearance, coprolites are composed of pulverized indigestible remnants of the organism's food, such as portions of scales, bones, teeth or shells, hence, they are very phosphatic in composition as well. These pulverized remains of food, otherwise known as "dung-stone," are preserved by process of petrification or cast and mold. They serve a valuable purpose in paleontology because they provide direct evidence of the predation and diet of extinct organisms. Coprolites may range in size from a few millimetres to over 60 centimetres. The term “agatized” is generally used to describe a fossil that has been replaced with chalcedony, a microcrystalline form of quartz. This happens through a process known as permineralization in which mineral rich groundwater seeps in and replaces the organic tissues of the plant or animal with silica, forming a crystal cast. This is a fairly common type of fossilization, and nearly all petrified wood is formed in this manner.The term agatized is also used when a fossil has hollow spaces, that have been filled with chalcedony rather than just the organic material being replaced. This is common in shells such as gastropods, clams and ammonites where the soft parts decay leaving a cavity inside of the shell. Origin is Western United States
