Protobranch bivalves are abundant and diverse in the Keasey Formation and include previously unrecognized genera and new species. They preserve novel and rarely-observed shell features including a “bandgrubenzahn” (bd) and escutcheonal perforations (ep). Life habits and functional anatomy distinguish nuculoideans, which lack siphons (A, nuculanids and B, pristigomids) from siphonate nuculanoideans (C,D). Courtesy of Carole Hickman
