The Detroit River Group is Middle Devonian: Discussion on "Early Devonian age of the Detroit River Group, inferred from Arctic stromatoporoids"

In their paper on the age of the Detroit River Group, the authors, E.C. Prosh and C.W. Stearn, suggest that the occurrence of two to four species of stromatoporoids in the Detroit River, which are also known to occur in well-dated Lower Devonian Arctic formations, outweighs the evidence of conodonts and goniatites that is currently used to date the Detroit River as mostly, or entirely, Middle Devonian. The conodont and goniatite evidence is much stronger than indicated by the authors and too strong to be set aside in response to their new data. Correlation difficulties are attributable to the known endemism of the eastern North American Early and Middle Devonian faunas and to environmental differences.