†Isorthis (Ovalella) Walmsley and Boucot 1975 (lamp shell)
Rhynchonellata - Orthida - Dalmanellidae
Parent taxon: Isorthis according to Walmsley and Boucot 1975
Sister taxa: Isorthis (Arcualla), Isorthis (Isorthis), Isorthis (Protocortezorthis), Isorthis alpha, Isorthis bailyi, Isorthis crassa, Isorthis estona, Isorthis festiva, Isorthis loveni, Isorthis mediocra, Isorthis parvulus, Isorthis pygmaea, Isorthis slitensis
Subtaxa: Isorthis (Ovalella) arndellensis Isorthis (Ovalella) mackenziei Isorthis (Ovalella) natiscotekia
Ecology: stationary epifaunal suspension feeder
Distribution:
• Silurian of Canada (6: Quebec collections), Mexico (6), Norway (2), the United Kingdom (2)
• Ordovician of Australia (5)
Total: 21 collections each including a single occurrence