Description. These borings have a distinctive radial pattern, with regular dichotomous bifurcations. The central point of the boring network is usually just below the surface of the substrate. Two, or more rarely three, initial branches contact the surface of the bone and thereafter stay as surface borings. The borings are either round or flattened in cross section, and between 3 and 7 μm across, retaining a constant width throughout the network. These borings bifurcate at intervals of 20 to 40 μm , with each branch dichotomously bifurcating at a similar distance, giving a very regular pattern. On a flat substrate, the proximal bifurcations enclose angles of between 90 and 120 degrees, although the angle between the more distal branches of the boring tends to be more acute, down to about 30 degrees.

Emended diagnosis. Distinctly regular and bilateral symmetrical ramification pattern, strictly dichotomous and prostrate, with angle of bifurcations decreasing towards the periphery of the trace. Nearly constant tunnel diameter and only weakly widened gallery terminations.