Archaeaspis macropleuron

Name: Archaeaspis macropleuron
Lieberman, 2002

Family: Archaeaspididae Repina, 1979

Superfamily: "Fallotaspidoidea" Hupé, 1953

Suborder: Redlichiina Richter, 1931

Order: Redlichiida Richter, 1932

Locality: Inyo-White Mountains, Inyo Co., Eastern California

Stratigraphy: Lower Cambrian , Fallotaspis Zone, Montenegro Mbr., Campito Fm.

Remarks: Photo courtesy of Bruce Lieberman

Discussion:

    The genus Archaeaspis Repina in Khomentovskii and Repina, 1965 has 3 known species:  A. hupei Repina in Khomentovskii and Repina, 1965; A. nelsoni Lieberman, 2002; and A. macropleuron Lieberman, 2002. Originally this genus was thought to be confined to the Siberian platform, however was found to also occur in the White-Inyo Mountains by Lieberman (2002). He described 2 new species and updated the diagnosis for the genus to include characters that emerged from his cladistic analysis. These 2 species include all specimens (in southwest USA) formerly asssigned to Fallotaspis and some specimens which were formerly assigned to Judomia.

    Apparently, all species formerly assigned to Fallotaspis in Laurentia are now assigned to Archaeaspis. If this is true, then there are many stratigraphic and biogeographic implications, including correlations with Moroccan sections. The revised taxonomy may suggest closer correlations with Laurentia and Siberia during this time, rather than between Laurentia and Morocco.

    We are awaiting news on whether the other fallotaspid species from the White-Inyo Mts. are also assigned to Archeaspis (links immediately below).

    Archaeaspis nelsoni differs from A. macropleuron Lieberman, 2002 in that A. macropleuron has relatively longer T3 pleural spines; a longer glabella that is closer to the anterior border furrow, and some characters of the anterior margin of the eye. Since these 2 species occur at similar localities, the minor differences were suggested to perhaps represent sexual dimorphs, rather than 2 distinct species. This is only a suggestion, as sexual dimorphism is difficult to prove and has not as yet been shown in olenellids.

Reference: Lieberman, Bruce S. (2002)  Phylogenetic analysis of some basal early Cambrian trilobites, the biogeographic origins of the Eutrilobita, and the timing of the Cambrian radiation. Journal of Paleontology, Vol. 76, No. 4, pp. 692-708.