RIGHT: Hughmilleria socialis, part of a windrow of abundant eurypterid remains collected by currents and deposited in the muds that became the Pittsford Shale (Member) of the Silurian lower Vernon Formation (Salina Group) in Western New York State. Specimens are believed to be molts that became disarticulated upon transport from their original environment, perhaps rivers dumping their loads into nearshore lagoons. The fishlike form of this eurypterid suggests that they were active swimmers, perhaps swimming in schools. Generally, preservation is due to storm events. Occurrences are extremely localized, yet occur over widespread areas including similar in rocks in Pennsylvania. Lingulid brachiopods are often associated with most occurrences.
The fauna was discovered by Clifton J. Sarle and described in 1903. Check out http://eurypterid.net for further information.
The Pittsford Shale bears abundant mudcracks, attesting to the shallowness of the waters in which specimens are preserved. In addition, at least some of the layers of the Pittsford Member contain much evidence of hyptersalinity in the form of SALT HOPPER (Halite) structures.
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