Bee burrows in the Late Cretaceous (Late Cenomanian) Dakota Formation, northeastern Arizona

Cretaceous burrows attributable to bees are the earliest known record of activity by those insects and are equivalent in age to, or possibly older than, the oldest known bee body fossil. The burrows consist of vertical shafts from which short lateral corridors and numerous brood cells open. They occur in a lenticular fluvial sandstone in the middle carbonaceous member of the Late Cretaceous (Late Cenomanian) Dakota Formation. A new ichnospecies, Celliforma dakotensis, is proposed for this trace fossil, which is distinguished from other members of the ichnogenus by the size of the brood cells and the nest architecture. The presence of these burrows is consistent with the environmental interpretation of this part of the Dakota Formation as representing an aggrading coastal plain.