Limiting the known range of archaeocyath to the middle Cambrian: Antarcticocyathus webersi Debrenne et al. 1984 is a lithistid sponge.

Antarcticocyathus webersi, reported from the upper Cambrian of central West Antarctica, was originally described as an archaeocyath. It was compared with the late Cambrian species Wilbernicyathus donegani, which was thought to be an archaeocyath. W. donegani was subsequently identified as a lithistid sponge belonging to the Family Anthaspidellidae. Examination of the type material reveals that A. webersi is also an anthaspidellid sponge. Until now, A. webersi was the only taxon generally regarded as a late Cambrian 'archaeocyath'. Recognition of A. webersi as an anthaspidellid sponge suggests that archaeocyaths did not continue beyond the middle Cambrian. [ABSTRACT FROM AUTHOR]