Interpretation of marine and freshwater paleoenvironments in Permo–Carboniferous deposits

The freshwater criteria of Gray [Gray, J., 1988. Evolution of the freshwater ecosystem: the fossil record. Palaeogeogr. Palaeoclimatol. Palaeoecol. 62, 1–214.] are discussed relative to North American Permo–Carboniferous deposits. The faunas of the Permo–Carboniferous basins of North America are compared with those from Europe; they are very similar. Organisms, which live or lived in the aquatic environment, can only characterize this environment; terrestrial animals and plants are extraneous to the aquatic environment. The best way of interpreting the environment is to compare with contemporaneous aquatic faunas. Myxinids, acritarchs, polychaetes, and some ostracodes are marine forms; spirorbiform microconchids (‘Spirorbis’) and some foraminifers are brackish water indicators. Based on faunal comparison the Permo–Carboniferous deposits of North America and Europe are interpreted as either marine or marine influenced.