Penion proavitus
Penion proavitus is an extinct species of marine snail or whelk, belonging to the true whelk family Austrosiphonidae.
Description
Penion proavitus fossils are the earliest known specimens of Penion siphon whelks. The species was medium-to-large in size.It is possible that fossils of Penion proavitus represent a stem lineage that was the common ancestor of Penion, Kelletia and Antarctoneptunea, instead of a species of Penion itself.