Chitinozoa and acritarcha of the Hamilton Formation (Middle Devonian), southwestern Ontario

The Middle Devonian (Givetian) Hamilton Formation of southwestern Ontario is rich in Chitinozoa and Acritarcha. Three cores from southwestern Ontario were sampled and numerous and varied palynomorphs were recovered. The Chitinozoa are represented by sixteen genera, two new, and forty-seven species, eight new; Acritarcha are represented by nine genera, one new, and twelve species, two new. The Chitinozoa-Acritarcha assemblages are relatively consistent with only two groups of Chitinozoa being stratigraphically differentiated: that of the species of Ancyrochitina, and the genera Desmochitina, Eisenackitina, and Pterochitina n. gen. Variation in relative percentages of Chitinozoa and Acritarcha is unrelated to lithological changes in the Hamilton Formation, but percentage trends do change at stratigraphic boundaries. The use of Chitinozoa and Acritarcha as biostratigraphical tools is strengthened because they appear to be unaffected by local ecological factors.