Anthozoa - Stauriida - Petalaxidae
Parent taxon: Stauriida according to E. W. Bamber and J. Fedorowski 1998
See also Hill 1981 and Sando 1983
Sister taxa: Arachnophyllina, Aulophyllina, Calostylina, Caniniina, Columnariina, Columnaxonidae, Cyathophyllina, Diffingiina, Heritschioides hammani, Ketophyllina, Kleopatrinidae, Lithostrotionina, Lomaphyllum, Lonsdaleiina, Lophophyllidiidae, Lophotichiidae, Lycophyllina, Mccloudius parvus, Metriophyllina, Mictocystoides, Nanophyllum, Paraceriaster, Petraphyllidae, Plerophyllina, Ptenophyllina, Romanophyllidae, Stauriina, Stereolasmatina, Streptelasmatina, Tachylasmatina, Yatsengiidae
Subtaxa: Cystolonsdaleia Huanglongophyllum Ivanovia Lithostrotionella Lytvophyllum Omaniphyllum Paralithostrotion Petalaxis Protoivanovia
Ecology: stationary epifaunal suspension feeder
Distribution:
• Permian of Bolivia (2 collections), Canada (14: British Columbia), China (15), Iran (1), Oman (1), Tunisia (1), United States (32: Alaska, California, Nevada, Oregon)
• Carboniferous of Algeria (1), Canada (38: Alberta, Nunavut), China (6), Ireland (4), Japan (6), Morocco (6), the Russian Federation (1), Spain (1), Svalbard and Jan Mayen (1), Türkiye (1), Ukraine (4), the United Kingdom (5), United States (22: Alaska, California, Georgia, Idaho, Montana, Nevada, Texas, Utah, Virginia)
Total: 162 collections including 194 occurrences