Mannopyge halli

By Kane

• January 1, 2018

Taxonomy

Kingdom: Animalia
Phylum: Arthropoda
Class: Trilobita
Order: Proetida
Family: Proetidae
Genus: Mannopyge
Species: Mannopyge halli
Author Citation Hall, 1861; Stumm, 1953, rev. Ludvigsen, 1987

Geological Time Scale

Eon: Phanerozoic
Era: Paleozoic
Period: Devonian
Epoch: Early

Stratigraphy

Hamilton Group
Amherstberg Formation
Formosa Member

Provenance

Collector: Kane Faucher
Date Collected: 05/01/2017
Acquired by: Field Collection

Location

London
Ontario
Canada

• amherstberg fm
• devonian
• trilobite

Comments

Found among imported fill from various locations, all Devonian (Dundee Fm, Amherstberg Fm, and Bois Blanc Fm). The Amherstberg Formation occurs above the Bois Blanc, and beneath the Lucas. Trilobites in the Amherstberg are quite rare as this formation is generally dominated by reef-building corals and stromatoporoids. The more common trilobite (although still relatively rare in this formation) would be Crassiproetus, followed by Mannopyge halli, Mystrocephalus, Acanthopyge, and Harpidella species.

Initially described by Hall as Proetus verneuli by Hall (1861), then Stumm (1953) as Dechenella halli, it was later renamed Mannopyge halli by Rolf Ludvigsen (1986). 

Whole specimens are not yet known, but cranidia, pygidia, and some thoracic segments have been reported. 

"A warburgelline with pear-shaped glabella, deep sigmoid 1s furrow, narrow (tr.) and faint 2s and 3s furrows; no preglabellar field, tropidium, or tropidial ridges. Large eyes located anterior of cephalic midlength; genal spines short. Semicircular pygidium lacks a flat border,-axis with 9 - 10 node-bearing

rings, eight faint pleural furrows and incised interpleural furrows, each pygidial rib terminates abaxially as a rounded node isolated by moderately deep paradoublural furrow." (Ludvigsen, 1987 p. 683). 

This species is well defined by its rounded nodes (shown in the picture), with the name "Mannopyge" being a combination of "manno" (necklace) and "pyge" (tail). 

As trilobites in this formation are rare, this is a somewhat exceptional find. I have yet to find any other examples of this trilobite in the collecting area.

A big thanks to @piranha for his expertise in identifying this find.

Sources:

Ludvigsen, R. (1987). Reef trilobites from the Formosa Limestone (Lower Devonian) of southern Ontario. Canadian Journal of Earth Sciences 24. 676-88.