Well Preserved Choia, Cambrian Explosion Fossil Sponges

This plate contains two sponges of the Genus Choia (Choia utahensis with the radiating spines) from the Cambrian Explosion strata of the Marjum Formaion, Millard County, Utah. Genus Choia are members of Class Desmospongia, Family Choiidae. Choia lived on the seafloor unattached and filtered food particles from the water. Choia are very rare in the Burgess Shale.

Sponge fossils from the Cambrian Explosion are found in various Cambrian sites in North America, most notably the Burgess Shale of Canada, and the Cambrian strata of Utah, like this specimen. Many sponges are also described from the Chengjiang biota of China. Sponges are believed to have undergone repeated radiations in the Phanerozoic, and probably attained their largest diversity in the Cretaceous.

Rigby, J.K. (1983). Sponges of the Middle Cambrian Marjum Limestone from the House Range and Drum Mountains of western Millard County, Utah. Journal of Paleontology 57, 240-270.