Petasosella margaretta is found from the Miocene of southern Australia,
Original description: Petasosella margaretta Bock & Cook, 1998
Locality: Grices Creek, Victoria, Australia
Holotype: MOV P303134
Reference: Bock, P.E. & Cook, P.L., 1998. Otionellidae, a new family including five genera of free-living lunulitiform Bryozoa (Cheilostomatida). Memorie di Scienze Geologiche 50: 195-211.