A day and a night in the life of a cleft-foot clam: Protovirgularia-Lockeia-Lophoctenium

A remarkable specimen of a compound trace fossil in Pennsylvanian sandstone comprises three very different ichnotaxa in conjunction: Protovirgularia dichotoma, Lockeia siliquaria and Lophoctenium isp. The combined activities represented by these ichnotaxa reflect the locomotion, resting and feeding behavior of a cleft-foot, protobranch clam (bivalve) that burrowed through the sediment, paused five times to deposit-feed, and then burrowed on to a new location, possibly as a reaction to a depositional event. It is estimated that the complete trace fossil was made in 24 hours or less. The three ichnotaxa also provide morphologic details of the bivalve's shell and soft parts (foot and labial palps).