Jamesonichnites heinbergi Dam, 1990

Diagnosis: Cylindrical meniscus filled tunnels with a distinct mantle, arranged in a subhorizontal chevron-shaped burrow system.

Description: cylindrical tunnels arranged in a subhorizontal chevron-shaped burrow system, generally preserved in concave epirelief; length of burrow system is 6-15 cm and is up to 7 cm in width. The cylindrical tunnels are meniscus filled and have a structureless mantle that is separated from the surrounding sediment and central fill by thin micaceous mud linings; width of tunnels is 10-20 mm and the thickness of the mantle varies between 2-3 mm; central fill is often weathered out and only marked as well-preserved transverse furrows, less than 1 mm across, on the inside of the mantle; spacing of furrows is 2-5 mm. The tunnels divide alternately from each side of the midline of the burrow system, giving rise to the chevron-shaped pattern; distally, the tunnels become vertical or nearly vertical and extend up to 5 cm in height.