Enigmatic Mississippian Bear Gulch Conularid Fossil

Description: The Bear Gulch Limestone is a deposit of some 70 square km in extent and 30 m in depth that has been a source of one of the most diverse assemblages of fossil fish with some 110 species having been described over the past 30 years. Most were new to science, and provided a unique view of the marine environment of Mississippian times. Fine preservation of both fish and invertebrates is a hallmark of these deposits, presumably due to an anoxic depositional environment. This specimen is a Conularid. Conulariids have been a subject of speculation for over a century and a half. They ranged from the Middle Ordovician to the Triassic. Exactly what they were is still not settled. Because of their fourfold symmetry, they have often been placed in the Cnidaria. However, their skeleton was very different from anything known in the Cnidaria, and they may represent a separate, extinct phylum The Conulariids had elongated, pyramidal exoskeletons, made up of rows of calcium phosphate rods. Most were square or rectangular in cross section, with prominent grooves at the corners. They lived attached to hard objects by a flexible stalk, and often lived in groups. They are thought to have been filter feeders; how they reproduced is not known.

Reference: Babcock, L.E. 1991. The enigma of conulariid affinities. Pp. 133-143 in A.M. Simonetta and S. Conway Morris (eds.). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.