Reevaluation of the formation of spiral coprolites

Abstract—The type D valvular intestine of the extant elasmobranch Scyliorhinus canicula produces fecal ribbons that coil spirally within the colon. Spiral fecal masses are expelled from the body without distortion. These masses are similar in morphology and internal structure to heteropolar coprolites from the Wymore Shale of Permian age in Kansas, which were previously described as enterospirae (fossilized valvular intestines). FOSSILIZED FECES are called coprolites. Amstutz (1958) reviewed the literature defining copro-lites and provided criteria for their identifica-tion. One type of ' coprolite, a spirally coiled form, first gained attention in the early 19th century. Mantell (1822) concluded that it was of animal origin and was not a fir cone as origi-nally thought. His conclusion was based on the composition of the fossil, inclusions, and the testimony of a Mr. Konig of the British Mu-seum. Konig noted a peculiar smell, unlike any in the plant kingdom, when hydrochloric acid was applied to the fossil. Spiral coprolites were first recognized as fossilized feces by Buckland (1829). Fritsch (1895) and Neumayer (1904) concluded that spiral coprolites are fossilized 'Manuscript received March 15, 1985. valvular intestines, for which Fritsch (1907) proposed the term enterospirae. Williams (1972) described in detail spiral coprolites from the Permian of Kansas and agreed that they are enterospirae. Subsequently, Stewart (1978), Duffin (1979), and Jain (1984) also described spiral coprolites with enterospiric morphology. Spiral coprolite studies have been reviewed b