Paleoenvironmental and temporal significance of variably colored Paleozoic orthoconic nautiloid cephalopod accumulations

► Review of Lower Paleozoic accumulations of orthoconic nautiloid cephalopods. ► Identification of common factors by comparing the color of their enclosing sediments ► Black to gray color generally represent event beds. ► Red-brown generally associated with discontinuity surfaces and condensed sequences. ► Silurian and Devonian accumulations may be considered as time specific facies.