Diplocraterion

Diplocraterion is an ichnogenus describing vertical U-shaped burrows having a spreite (weblike construction) between the two limbs of the U. The spreite of an individual Diplocraterion trace can be either protrusive (between the paired tubes) or retrusive (below the paired tubes). Some ichnospecies have both types (e.g., Diplocraterion yoyo). The presence/absence of funnel-shaped openings should not be used as an ichnotaxobase due the high probability that the upper portions of the trace may have been eroded away.