Preservation of eurypterid remains in the Late Silurian sequences of New York and adjacent Ontario, Canada.
|Samuel J. Ciurca, Jr., Rochester, New York|
|Preservation of eurypterids, as personally observed over the past 40 years, indicates that if you can imagine a specimen being preserved in any fashion, you can find it. Most studies are limited to specimens in mus- eum drawers. Rarely, a researcher is intimately in- volved in field studies long enough to observe almost limitless specimens necessary to really make an accurate evaluation of the occurrence and distribution of the eurypterid material being collected.|
|ABOVE: A fine specimen of Eurypterus lacustris from the Williamsville Waterlime, Bertie Group, of Western New York. Note that the anterior appendages are mostly preserved. The telson was not preserved. The curved aspect preserved in this specimen (which appears to make the animal look like it is swimming) is undoubtedly due to its being deposited in this dolomitic mud during a storm event.
Isolated eurypterid parts are commonly found. They consist of complete swimming legs, individual joints of swimming legs, telsons, body segments, metastomas, coxae, walking legs and spines, the doublure (or half a doublure), the sex appendage (isolated or still attached to an operculum - you name the part or fraction thereof, and you can find it. And most can be utilized to identify the eurypterid they came from.
|Grazing: Fragmentary eurypterid remains are so abundant, especially in windrows, that we ought to be able to observe features that modify the remains we observe. Remains can be ripped apart during trans- portation, distorted, or piled up into masses of debris like wood piled up on a beach. BELOW is a carapace of Eurypterus lacustris that appears to have been attacked by a grazer (gastropod?) so as to completely modify the outline of the carapace. The carapace appears to have been nibbled at (like a 'leaf cutter' on a leaf).|
|ABOVE: A relatively large carapace of Eurypterus lacustris from the Rte. 3 Quarry (abandoned and filled in) in Ontario, Canada. CIURCA 062666-1, Williamsville Waterlime, Bertie Group. Length: about 5.4 cm. Width (at base): about 8.4 cm.
The carapace probably hit an object or stiff substrate during a storm. The front was split open (note the wrinkles). Other parts of the carapace were either ripped apart or split. The groves present on the carapace indicate traces - something was moving around on the carapace and left these impress- ions. Other than the obvious destructive forces at work before the carapace was finally buried, this specimen is well-preserved.
|ABOVE: This is not an ostracod, nor a clam, but an isolated eye of the eurypterid, Eurypterus lacustris. Some integument is still attached. And it looks like something was 'nibbling' at the integument. While isolated eyes are not commonly found, I have had the opportunity of collecting several, including a very large eye of a pterygotid - complete with its facets. Specimen number 082004-1Web from waterlime (Williamsville Formation, Ridgemount Quarry South, Ontario, Canada.|
|ABOVE: Another example showing wrinkling on the left side, possible bite marks and shredding of the carapace. Note area around the eye. E. lacustris, CIURCA 980217- .|
|LEFT: Still another type of preservation. CLICK on carapace to look at larger view and description.
Eurypterus lacustris from the Williamsville Water- lime of Ontario, Canada.
CIURCA 980217- .
|ABOVE: Another example showing that the entire left side of the carapace has been chewed. This is another E. lacustris, CIURCA 980217- .|
|SEE ALSO: Eurypterus lacustris 4|
|Eurypterid Preservation 2|
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