Trilobites of the Naiset Formation



Naiset Formation, Early Middle Cambrian, eastern Main Ranges, southern Canadian Rocky Mountains, Alberta and B. C.



Trilobite List:


This list is mainly from an unpublished thesis (Tremblay, 1996). Tremblay (1996) has many changes in his thesis which may or may not be agreed upon until published. For example, he synonymized Amecephalus with Alokistocare. Also he included all of the following genera in Antagmus: Poulsenia, Onchocephalus, Piazella, Eoptychoparia, Parapoulsenia, Spencella, Nyella, and Illtydaspis. This is almost certainly not agreed upon by trilobite workers in the Cambrian.




Alokistocare cleora (Walcott, 1917) [old name Amecephalus cleora] (see Tremblay, 1996, unpubl. thesis; and Fletcher & Collins, 2003)

Amecephalus agnesensis (Walcott, 1912 – or is it 1917?) (changed to Alokistocare agnesensis (Rasetti, 1951) in Tremblay, 1996 unpubl. thesis) (should be called Amecephalus agnesensis until published) – not sure on the generic status of this species.

Ogygopsis klotzi (Rominger, 1887)

Oryctocephalites sp. indet. 2 Rasetti, 1951

Piazella tuberculata (Rasetti, 1951) (Tremblay, 1996 refered this species to Antagmus, however it is not published)

Poliella denticulata Rasetti, 1951

Poliella prima (Walcott, 1908) (reported in Tremblay, 1996 unpubl. thesis)

Stephenaspis bispinosa Rasetti, 1951 (Tremblay 1996 unpubl. thesis synonymized Stephenaspis with Fieldaspis. Refer this species to Stephenaspis until published)

Syspacephalus crassus Rasetti, 1951

Syspacephalus perola (Walcott, 1917)

Syspacephalus laticeps Rasetti, 1951

Syspacephalus laevigatus Rasetti, 1951

Wenkcheminia sulcata Rasetti, 1951 (synonomized with Wenkcheminia walcotti Rasetti, 1951 in Tremblay, 1996 unpubl. thesis) (should be called W. sulcata Rasetti, 1951 until published)

Wenkcheminia walcotti Rasetti, 1951





            The Naiset Formation is underlain by the Gog Group (Lower Cambrian) and overlain by the Cathedral Formation. It is uppermost Lower Cambrian to lower Middle Cambrian in age. The Naiset Formation (deeper water slope facies) is correlative with the Peyto Formation (shallow subtidal and shoal facies) and the Mt. Whyte (subtidal to shelf facies). The Naiset likely includes the upper part of the Bonnia-Olenellus Zone (Olenoides fieldensis Zone of Tremblay, 1996) and the entire Plagiura-Poliella Zone (Plagiura-Kochaspis zone and Wenkchemnia-Stephenaspis Zone). Tremblay, 1996 introduced a new zonation and biofacies concept for the Peyto, Mt. Whyte, and Naiset Formations, although this is not published.

            Since the Naiset Formation is mainly exposed in Canada’s mountain parks, collecting is forbidden. The exposures in the eastern Main Ranges of the Rockies are within Jasper, Banff, Yoho, and Kootenay National Parks.





Rasetti, F. (1951)  Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, Volume 116, No. 5, 277 pp.


Tremblay, J. V. (1996)  Trilobites and Strata of the Lower and Middle Cambrian Peyto, Mount Whyte and Naiset Formatiopns, Alberta and British Columbia. Unpublished Ph.D. thesis, McMaster University, Hamilton, Ontario.

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