Trilobites of the Rochester Shale, New York
last revised 01 MAY 2018 by S.M. Gon III
Locality: Caleb's Quarry, Middleport, New York, USA
Stratigraphy: Lewiston Member, Rochester Shale Fm., Clinton Grp.
Age: Lower Silurian (Wenlockian), ca 425 Mya
The Caleb Quarry, Western New York (courtesy of American Museum of Natural History)

Location of the Rochester Shale today
Location of the Rochester Shale in the Lower Silurian

The rich fossils of the Lower Silurian Rochester Shale were originally uncovered during the construction of the Erie Canal between the Mohawk River at Rome, NY, and Lake Erie at Buffalo, between 1817 and 1825. During the building of the canal locks at Lockport, the rich fossil lagerstätte was documented (Arctinurus boltoni was the second trilobite species to be documented from the state of New York). Caleb's Quarry, established in 1988, is a shale pit providing material to line wastewater containment ponds, but paleontologists soon recognized the richness of the diggings, which also included significant echinoderm specimens. This quarry bears the same trilobite fossils as at Lockport (18 km away) and Niagara Gorge (46 km away). An agreement between the quarry owner and commercial collectors opens the area to systematic collecting. Because of the sheer volume of material quarried and the large series of specimens collected, much information on size ranges and ecology of these trilobites has been collected. Specimens with healed injuries suggest predators were active. Larger specimens with epibionts such as brachiopods suggest that larger specimens did not molt frequently, allowing creatures to grow on their exoskeletons. The most common of the Lewiston Member trilobites are depicted below (some images from the American Paleontologist article cited below):

Dalmanites limulurus
(Green 1832)
Calymene niagarensis
(Hall 1852)
Bumastus ioxus
(Hall 1852)
Arctinurus boltoni
(Bigsby 1825)

Radnoria bretti
Adrain & Tetreault 2005
Trimerus delphinocephalus
Green 1832
Decoroproetus corycoeus
(Conrad 1842)
Dicranopeltis nereus
(Hall 1863)

via Trilobites of New York (Whiteley et al 2002)

Order Phacopida
Suborder Cheirurina
Family Cheiruridae
Cheirurus sp.
?Deiphon pisum (Foerste 1893)
Staurocephalus sp.
Suborder Phacopina
Superfamily Dalmanitoidea
Dalmanites limulurus (Green 1832)
Suborder Calymenina
Family Calymenidae
Calymene sp.
Calymene niagarensis (Hall 1852)
Diacalymene sp.
Family Homalonotidae
Trimerus delphinocephalus Green 1832

Order Corynexochida
Suborder Illaenina
Family Illaenidae
Bumastus ioxus (Hall 1852)
Illaenoides cf. triloba (Weller 1907)

Order Lichida
Superfamily Lichoidea
Family Lichidae
Acanthopyge sp.
Arctinurus boltoni (Bigsby 1825)
Dicranopeltis nereus (Hall 1863)
Trochurus halli (Foerste 1917)

Order Proetida
Superfamily Aulacopleuroidea
Family Aulacopleuridae
Maurotarion sp.
Superfamily Bathyuroidea
Family Brachymetopidae
Radnoria bretti Adrain & Tetreault 2005
Superfamily Proetoidea
Family Proetidae
Decoroproetus corycoeus (Conrad, 1842)
Some New York Rochester Shale references:

American Museum of Natural History: Trilobites of the Rochester Shale maintained by Andy Secher and Martin Shugar, 2010.

Whiteley, T.E., G. J. Kloc & C.E. Brett. 2002. Trilobites of New York. Cornell University Press.

Whiteley, T.E. & K. Smith. 2001. Fossil Lagerstatten of New York 3: Caleb's Quarry: Part 1 - the trilobites. American Paleontologist 9(1):3-5.

Adrain, J.M. & D.K. Tetreault. 2005. The brachymetopid trilobite Radnoria in the Silurian (Wenlock) of New York State and Arctic Canada. Can. J. Earth Sci./Rev. Can. Sci. Terre 42(12): 2087-2096.

Primitive Worlds (featuring the Rochester Shale trilobite species above)

Related locality: Walcott-Rust Quarry, NY
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