Erieopterus microphthalmus, characteristic of the Early Devonian strata throughout New York and Ontario, Canada (type Olney Limestone, Thacher Limestone, Chrysler Formation, Honeoye Falls Formation south of Rochester, and the Clansbrassil Formation of Ontario, Canada). Only one other eurypterid has ever been found associated with Erieopterus, i.e. an Acutiramus that evolved from the Bertie Group forms (viz. Acutiramus cummingsi of the Williams- ville Waterlime). The specimen shown here is from the upper Olney Limestone just west of Syracuse, New York (SRQ). The eurypterid remains are part of a windrow analogous to occurrences in the Bertie waterlimes. Ostracods commonly occur especially in clusters and the brachiopod, Howellella vanuxemi is characteristic except in the western occurrences. A shallow basin, subjected to desiccation and shoreward of stromatoporoid banks, is envisioned. It is quite likely that Erieopterus lived in shallow marine waters and, during storms, molted and disar- ticulated remains were washed inshore even onto a 'beach' made of calcareous mud.
Reports of pre-Devonian occurrences of Erieopterus (e.g. Willard P. Leutze, 1961) are probably erroneous. At this time several carapaces with exceedingly circular outlines were interpreted as belonging to Erieopterus, though other portions of the body were unknown. Yet, the Early Devonian Erieopterus had to arrive across the Silurian/Devonian Boundary from some preexisting form. To date, this form has not been identified - Erieopterus appears abruptly in the Early Devonian sediments of New York and adjacent areas. Note: While Erieopterus abruptly replaces the Silurian series of Eurypterus species across the boundary, Acutiramus (oceanic?) continued to evolve across the boundary occurring prolifically in certain facies of the Olney Limestone (Manlius Group) of central New York.
Samuel J. Ciurca, Jr., December 28, 2005 |
