Diagnosis: Single elongated groove of biogenic origin on skeletal material (e.g., bones, teeth). The groove, U-or V-shaped in transverse section, may only affect the surface of the bone, or bone-fibres may be cut through, recurved or brocen within the groove. The groove has serrated morphology.

Emended diagnosis: Single elongated, straight or curved groove of biogenic origin on skeletal material (e.g., bones, teeth). The groove, U- or V-shaped in transverse section, may affect different kinds of biogenic mineral substrates (mainly vertebrate and invertebrate skeletons). The groove has a serrated or non-serrated morphology (after Jacobsen and Bromley 2009).