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Showing results for tags 'humboldt range'.
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The Anisian (Middle Triassic) ammonite faunas of Nevada have long been known to provide the most complete sequence for this stage in the world, with many genera such as Gymnotoceras, Frechites, and Nevadites being represented in abundance at classic sites such as Fossil Hill in the Humboldt Range. Here I will illustrate three less common to rare forms that are also present in Middle Anisian strata in Nevada. Unionvillites hadleyi (Smith) Provenance: Humboldt Range, Congress Canyon near Unionville Age: Middle Anisian, Hyatti Zone, Hadleyi Subzone A well-preserved specimen showing the braided keel. Reference: Bucher, H., "Ammonoids of the Hyatti Zone and the Anisian Transgression in the Triassic Star Peak Group, Northwestern Nevada, USA" (Palaeontographica 223, pp. 137-166, Stuttgart, 1992). This keeled, tuberculate form has been reported from a few localities in the Humboldt Range. Semibeyrichites sp. Provenance: Humboldt Range, Big Canyon north of Unionville Age: Middle Anisian, Hyatti Zone, Mctaggarti Subzone Reference: Bucher (1992) above. Bucher reported two specimens from the Humboldt Range as the first occurrence of this genus in the western hemisphere. This specimen was found very close to Bucher's locality. Chiratites bituberculatus Monnet and Bucher Provenance: south of Favret Canyon, Augusta Mountains Age: Middle Anisian, Shoshonensis Zone, Mojsvari Subzone Reference: Monnet, C. and Bucher, H., New Middle and Late Anisian (Middle Triassic) ammonoid faunas from northwestern Nevada (USA): taxonomy and biochronology (Fossils and Strata, 52, 2005). Monnet and Bucher proposed this species on the basis of a single specimen from the Augusta Mountains. I have since discovered about six specimens at another nearby locality.