Diplocraterion


Diplocraterion is an ichnogenus describing vertical U-shaped burrows having a spreite between the two limbs of the U. The spreite of an individual Diplocraterion trace can be either protrusive or retrusive. Some ichnospecies have both types. 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. Observation of the orientation of Diplocraterion in the field is frequently used to determine the way up of rock strata at outcrop.
There are several ichnospecies of Diplocraterion.

[Ethology]

The various ichnospecies of Diplocraterion provide a good example of how ethology can be interpreted from trace fossils. Diplocraterion is a classic example of equilibrichnia. These types of traces represent gradual adjustments to background sedimentation and erosion rates and reflect the efforts of the organisms to maintain a specific depth within the substrate. This movement within the substrate produces the two types of spreite characteristic of Diplocraterion and other ichnotaxa.
Most Diplocraterion show only protrusive spreit. These indicate that the trace was produced under predominantly erosive conditions where the organism was constantly burrowing deeper into the substrate as sediment was eroded from the top. D. yoyo has both protrusive and retrusive spreiten indicating highly variable conditions leading to the need for the organisms to constantly adjust itself up and down within the substrate to maintain equilibrium and not become exposed or buried.