THE AGE OF THE DUNKARD: HAVE WE LEARNED ANYTHING IN 120 YEARS?
Overall, the Dunkard Group contains a Late Pennsylvanian (Stephanian) fossil flora with sporadic occurrences of taxa suggestive of the Early Permian. Palynomorphs extracted from Dunkard coaly beds generally support a Late Pennsylvanian, possibly transitional Permian, age. Fossil macrophytes have proven more problematic to interpret. Three distinct paleofloras have been recognized that occupied different niches during the Late Carboniferous-Permian transition. Early workers placed utmost importance on the first occurrences of Permianesque forms such as Callipteris (Autunia) conferta, Taeniopteris jejunata and Walchia. These xerophytes, first reported from the older Conemaugh Group, lived contemporaneously in extrabasinal environmental settings with the relic late Westphalian-like wetlands floras and replaced the “normal” lowland Stephanian flora during drier, interglacial periods. As a result, Dunkard paleofloras provide a mixed and confusing biostratigraphic signal. Vertebrate and invertebrate fossils known from Dunkard strata, mainly non-marine bivalves, branchiopods, serpulid worms, and rare Lingula, are of limited biostratigraphical utility. Until more definitive fossils are found, the exact age of the Dunkard cannot be resolved closer than transitional “Permo-Carboniferous.”