Diagnosis: Excrement in form of pills with a specific shape, without characteristic connection to each other (translated from RICHTER & RICHTER 1939:163-164).
Remarks: Richter & Richter (1939) proposed Coprulus as an informal name, thus creating a nomen nudum. Mayer (1952) was the first to erect ichnospecies for Coprulus and thus must be regarded as its author. C. oblongus and C. sphaeroideus are merely established based on slight differences in size, which is not an adequate ichnotaxobase (Bertling et al., 2006). Therefore, C. oblongus is herein regarded as type ichnospecies of Coprulus, with C. sphaeroideus as its junior synonym. Coprulus (Nuculidarum?) sensu Gramann(1966) and Coprulus sensu Gaillard (1978) differ in shape and sculpture from the original diagnosis and thus belong to a different ichnogenus. Ichnotaxonomically, Coprulus differs from trace fossils filled with pellets, such as, for instance, Alcyonidiopsis and Tomaculum (Eiserhardt et al. 2001). These are true compound structures, being created by a single producer simultaneously.