''Sphenothallus'' is a problematic extinct genus lately attributed to the

conulariids Conulariida is a poorly understood fossil group that has possible affinity with the Cnidaria. Their exact position as a taxon of extinct medusozoan cnidarians is highly speculative. Members of the Conulariida are commonly referred to as conularii ...

. It was widespread in shallow marine environments during the

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

Occurrence

''Sphenothallus'' is represented in the Cambrian period in the Kaili biota and the

Mount Stephen trilobite beds The Mount Stephen trilobite beds (UNSM locality 14s) are a series of fossil strata on Mount Stephen, British Columbia that contain exceptionally preserved fossil material. Part of the same stratigraphic unit as the Burgess Shale deposit, many non- ...

, where it co-occurs with the similar organisms ''

Cambrorhythium ''Cambrorhytium'' is an enigmatic fossil genus known from the Latham Shale (California), and the Chengjiang (China) and Burgess Shale (Canadian rockies) lagerstätte. 350 specimens of ''Cambrorhytium'' are known from the Greater Phyllopod bed, ...

'' and ''

Byronia ''Byronia'' is a genus of theca-bearing cnidarians with a close affinity to the coronatid scyphozoa The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or "true jellies"). The class nam ...

''. It is known in younger strata in Canada and the US, surviving at least until the

Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago *Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD ...

Ecology

''Sphenothallus'' lived in groups as an opportunist in environments from

hardground Carbonate hardgrounds are surfaces of synsedimentarily cemented carbonate layers that have been exposed on the seafloor (Wilson and Palmer, 1992). A hardground is essentially, then, a lithified seafloor. Ancient hardgrounds are found in limestone ...

Occurrence

Ecology

Notes

References

External links