plate contains three sponges of the Genus Choia (Choia utahensis
with the radiating spines, and the other unknown) from the Cambrian
Explosion strata of the Wheeler Formation in 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. There is also another
fossil I can’t identify.
Choia is a rarer genus of sponge (Phylum Profera)
with radiating spines, and is also found in the Burgess Shale. This
plate was found in the Wheeler Shale’s so-called 'red beds',
as the plate’s color attests. This is an excellent specimen
of two very different organisms from the Cambrian Explosion with
rare preservation and very nice contrast.
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.