Two New, Substrate-Controlled Nonmarine Ichnofacies

Substantial ichnocoenoses of ichnofossil assemblages in nonmarine environments can be grouped into two, substrate-controlled ichnofacies. These are traces in plant tissues (mostly wood and leaves) and in bone. Plant tissues and bones provide distinctive, hardground substrates that are colonized and/or utilized in the nonmarine realm by a substantial diversity of organisms, mostly arthropods and microorganisms. The trace fossil record in plant substrates is diverse, extending back to the Devonian, and is dominated by borings in wood created for feeding, reproduction, and shelter and by feeding traces on leaves, including mines and galls. The Paleoscolytus ichnofacies named here includes nonmarine trace fossil ichnocoenoses dominated by feeding traces and borings of low to moderate ichnodiversity. Woody and foliar substrates typify the Paleoscolytus ichnofacies, and it is to some extent the subaerial counterpart of the previously named Teredolites ichnofacies. Bone provides a source for feeding, reproduction, and shelter for various arthropods; it is also a source of food for vertebrates, and it is modified in some settings by trampling and by human activities. Bone also undergoes bioerosion by microbial agentsbacteria, fungi and protozoans. The result is a diversity of traces preserved in fossil bone that encompass distinctive ichnofossil ichnocoenoses. The Cubiculum ichnofacies named here includes nonmarine and subaerial trace fossil ichnocoenoses dominated by macroscopic and microscopic borings produced by mobile feeders and the subordinate occurrence of damage by other bone utilizers, of generally low to moderate ichnodiversity and of high local abundance.