Calathium is an extinctgenus of organism found in marine beds of Ordovician age. Its classification is enigmatic: It has long been placed among the receptaculites,[1][2] but it has also been described as a quasi-sponge,[3] possibly akin to the archeocyathids[4] or other hypercalcified sponge.[5] The chief difference from archaeocyathids is that their walls were connected by rods rather than septae.[4]
The organisms were important reef-forming organisms during the Ordovician, forming communities with lithistid sponges that gradually displaced the earlier microbial mounds.[4]
References
^Fisher, Daniel C.; Nitecki, Matthew H. (January 1982). "Standardization of the Anatomical Orientation of Receptaculitids". Journal of Paleontology. 56 (S13): 1–40. Bibcode:1982JPal...56S...1F. doi:10.1017/S0022336000061928.
^Church, Stephen B. (July 1991). "A new Lower Ordovician species of Calathium , and skeletal structure of western Utah calathids". Journal of Paleontology. 65 (4): 602–610. Bibcode:1991JPal...65..602C. doi:10.1017/S0022336000030699.
^Toomey, Donald F.; Ingels, Jerome J. C. (1964). "Reported Silurian Occurrence of Calathium from the Thornton Reef, Illinois: A Correction". Journal of Paleontology. 38 (6): 1102–1104. JSTOR1301646.
^ abcLi, Qijian; Li, Yue; Wang, Jianpo; Kiessling, Wolfgang (May 2015). "Early Ordovician lithistid sponge– Calathium reefs on the Yangtze Platform and their paleoceanographic implications". Palaeogeography, Palaeoclimatology, Palaeoecology. 425: 84–96. Bibcode:2015PPP...425...84L. doi:10.1016/j.palaeo.2015.02.034.
^Meng, Miaomiao; Fan, Tailiang; Duncan, Ian (March 2021). "Sedimentary characteristics of the Lower to Middle Ordovician Calathium reefs in the northwestern Tarim Basin, NW China". Carbonates and Evaporites. 36 (1): 4. Bibcode:2021CarEv..36....4M. doi:10.1007/s13146-020-00665-7.
