The paleobiology and evolutionary affinities of conulariids have long been debated, but in recent decades it had been widely thought that conulariids were a group of septate cnidarians, belonging within or most closely related to the Class Scyphozoa. In the past several years, however, some investigators have claimed that conulariids represented a group of animals distinct from cnidarians and all other currently recognized phyla (e.g., Kozlowski, 1968), and Steul (1984) has argued that conulariids were most closely related to vertebrates. The steeply pyramidal, finely lamellar conulariid test shows numerous microstructural similarities to the steeply conical periderm of coronatid scyphozoans. These similarities, coupled with evidence obtained through analysis of healed conulariid test injuries and growth abnormalities, indicate that the conulariid test was an ectodermally secreted, mineralized periderm, similar, and possibly homologous, to the coronatid periderm. Conulariid specimens whose apical end terminates in a transverse wall, or schott, occur almost exclusively in sediments deposited under conditions of moderate or high current energy. Together with the absence of schotts in specimens whose apical end is more or less pointed, this indicates that schott-bearing specimens represent individuals that were broken, in life, by currents, and that lived to heal the site of injury. Such conulariids are similar to truncated coronatid polyps, which repair their broken apical end by producing a structure similar to the conulariid schott. Conulariids exhibit a substantially greater variety of internal test structures at their corners and midlines than hitherto realized. Comparisons of these structures with soft parts and internal peridermal structures of scyphozoans reveal numerous, detailed similarities that are best interpreted as indicating that conulariid midlines were sites of gastric septa, homologous to the septa of scyphozoans. Relic conulariid soft parts, including relics discovered by Steul (1984) and relics discovered here in Eoconularia amoena Sinclair, show intriguing similarities to soft parts of scyphozoan polyps undergoing polydisc strobilation. This suggests that conulariids, like many scyphozoans, exhibited alternating polypoid and medusoid generations. Finally, cladistic analysis of the interrelationships of conulariids and the extant cnidarian classes suggests that conulariids and scyphozoans are nearest relatives, and that together they and anthozoan cnidarians form a monophyletic group within Cnidarian that excludes hydrozoans.Ph.D.Earth SciencesPaleontologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/128457/2/9014034.pd
