''Rotadiscus'' is a genus of discoidal animal known from the Cambrian

Chengjiang biota The Maotianshan Shales () are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation or Heilinpu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized orga ...

and classified with the

eldonioid Eldonioids or velumbrellids are an extinct clade of disc-shaped cambroernids, the Eldonioidea (or Velumbrellida), which lived in the early to middle Paleozoic (Cambrian to Devonian). The terms "eldonioid" and "eldoniid" have been used somewhat in ...

s. As with other eldonioids, it was originally thought to have been pelagic, but is now thought to be benthic. In addition to the type species ''R. grandis'', two other ''Rotadiscus'' species have been proposed. The first is known only from one complete juvenile specimen and a few fragments, and was originally described as "''Brzechowia'' sp." It remains without a formal species name, but has been transferred to ''Rotadiscus''. The species initially described as ''R. guizhouensis'' has since been reassigned to the genus '' Pararotadiscus''. A 2023 cladistic analysis based on new fossils places ''Rotadiscus'', along with other eldonioids, as stem-group

ambulacraria Ambulacraria , or Coelomopora , is a clade of invertebrate phyla that includes echinoderms and hemichordates; a member of this group is called an ambulacrarian. Phylogenetic analysis suggests the echinoderms and hemichordates separated around ...

ns in the clade Cambroernida.

References

Cambroernids Fossils of China Fossils of Canada Prehistoric bilaterian genera Cambrian genus extinctions {{Cambrian-animal-stub