Tremichnus Brett, 1985

2.63. Circular holes and pit-shaped borings

Emended diagnosis.Circular pits, generally wider than deep, perpendicularly bored into ossicles of echinoderms.

Unbranched, circular, bioerosional trace.

Circular pits or embedment structures of varying diameter (about 0.1 to 4.0 mm) occurring on the plates of echinoderms, primarily crinoids, with or with out associated thickening or gall-like deformation of the plates. Pits regularly parabolic in cross section, with diameter/depth ratios variable from about 0.1–1.0; no internal expansion or other ramifications. Holes always oriented perpendicularly to external plate surfaces, tapering in ward; generally not penetrating through plates. Adjacent pits
may over lap one an other.