Specimen of the Month
Samuel J. Ciurca, Jr., Rochester, New York by Eurypterids.net
Eastern U. S. and Ontario, Canada
Zonation based on stratigraphic distribution of characteristic Silurian and
A. Rhinocarcinosoma (see note below), B, C. Hughmilleria socialis, Eurypterus
pittsfordensis (respectively), D. Waeringopterus, E. Eurypterus remipes, F. Eurypterus
lacustris, G. Erieopterus microphthalmus.
Modified from Ciurca, page D19, EURYPTERID BIOFACIES OF THE
SILURIAN-DEVONIAN EVAPORITE SEQUENCE: NIAGARA PENINSULA, ONTARIO,
CANADA AND NEW YORK in New York State Geological Association 62nd Annual
Meeting September, 1990 (Field Trip Guidebook Western New York and Ontario,
Fredonia State University College.
NOTE: In the chart above, Rhinocarcinosoma should be directed much lower in the
stratigraphic section as it is only known from the Illion-Sconondoa Members of the
Lockport Group in central-eastern New York.
Rhinocarcinosoma vaningeni (reconstruction), New
York and Pennsylvania. See Clarke & Ruedemann
(1912) THE EURYPTERIDA OF NEW YORK for an
interesting description of this bizarre eurypterid.
This chart does not show all of the
eurypterid horizons known, only those
in which species have been described.
Within the Salina Group, there are
additional horizons with distinctive
eurypterid occurrences - unfortunately,
these have not been studied in enough
detail to date.
Within the very thick Lockport Group,
consisting mostly of massive dolostone
(some highly quartzose), little is known
except for occasional finds of pieces of
eurypterid material. In Western New
York, the eurypterid horizons are all
within the uppermost beds. The genus
Eurypterus appears in uppermost beds
at Rochester (perhaps E. pittsford-
ensis). An unknown carcinosomatid
occurs above Niagara Falls associated
with large stromatolites (the specimen
is in the Peabody Museum of Natural
History at Yale University).
In Ontario, Canada, beds within the
Lockport-Guelph are slowly yielding
additional eurypterid faunas. Perhaps
one of the rarest is Tylopterella (see
Clarke & Ruedemann, 1912, for an
early description based on an almost
complete individual). Based upon its
construction, I wonder if Tylopterella
was actually a reef-dweller (coral and
After almost 200 years since the dis-
covery of the first eurypterid, there are
still many new horizons within Ontario,
Canada and the Appalachian Basin to
be described (especially Pennsylvania).