Bioerosion traces in Pliocene solitary corals

One of the basic taphonomic questions is whether the borings in skeletal structures were produced in vivo or post mortem. Borings influencing the growth of the skeleton were produced during the life of the animal; the same for borings that are distributed very close to the surface of the skeletal structure and are elsewhere known from deep penetration into the substrate. Conversely, borings that penetrate deeply into the skeletal structure and those that are always close to the surface, irrespective of the substrate, can be regarded as produced post mortem. These criteria are used to distinguish the two categories of polychaete, bryozoan, and phoronid borings made in coralla of fossil (Pliocene of Tunisia) solitary scleractinian coral Ceratotrochus.

Figure: Corallum of solitary Ceratotrochus (Edwardsotrochus) duodecimcostatus from the upper Pliocene of Tunisia (distal and lateral views); longitudinal thin-section and virtual (mCT) longitudinal section of the coral skeleton with probably in-vivo polycha ete borings (ichnogenus Maeandropolydora).