Ediacara biota
However, the burrows were later found below the GSSP which marks the base of the Cambrian, and their appearance is not related to any of the more significant biological events, such as the appearance of the small shelly fauna or the disappearance of the Ediacara biota. More detailed analysis of the fossils suggest that they might have been formed by extensive under-mat mining, rather than true vertical burrowing, which may go some way to explain this - they may not represent a fundamentally new biological innovation.