Both Exogyrinae and Gryphaeinae are completely extinct and only three genera "Hyotissa", "Neopycnodonte", and "Pycnodonte" in Pycnodonteinae have extant species.
Both Exogyrinae and Gryphaeinae are completely extinct. Only four genera "Hyotissa", "Parahyotissa", "Pycnodonte" and "Neopycnodonte" in the subfamily Pycnodonteinae have extant species.