Calathium Explained

Calathium is an extinct genus 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 or other hypercalcified sponge.^[4] The chief difference from archaeocyathids is that their walls were connected by rods rather than septae.^[5]

The organisms were important reef-forming organisms during the Ordovician, forming communities with lithistid sponges that gradually displaced the earlier microbial mounds.^[5]

Notes and References

1. Fisher . Daniel C. . Nitecki . Matthew H. . Standardization of the Anatomical Orientation of Receptaculitids . Journal of Paleontology . January 1982 . 56 . S13 . 1–40 . 10.1017/S0022336000061928. 1982JPal...56S...1F .
2. Church . Stephen B. . A new Lower Ordovician species of Calathium, and skeletal structure of western Utah calathids . Journal of Paleontology . July 1991 . 65 . 4 . 602–610 . 10.1017/S0022336000030699. 1991JPal...65..602C .
3. Reported Silurian Occurrence of Calathium from the Thornton Reef, Illinois: A Correction . Donald F. . Toomey . Jerome J. C. . Ingels . Journal of Paleontology . 38 . 6 . 1964 . 1102–1104 . 1301646.
4. Meng . Miaomiao . Fan . Tailiang . Duncan . Ian . Sedimentary characteristics of the Lower to Middle Ordovician Calathium reefs in the northwestern Tarim Basin, NW China . Carbonates and Evaporites . March 2021 . 36 . 1 . 4 . 10.1007/s13146-020-00665-7. 2021CarEv..36....4M .
5. Li . Qijian . Li . Yue . Wang . Jianpo . Kiessling . Wolfgang . Early Ordovician lithistid sponge– Calathium reefs on the Yangtze Platform and their paleoceanographic implications . Palaeogeography, Palaeoclimatology, Palaeoecology . May 2015 . 425 . 84–96 . 10.1016/j.palaeo.2015.02.034. 2015PPP...425...84L .