Palynology of the Ordovician Kanosh Shale at Fossil Mountain, Utah

Abstract

Palynomorph assemblages recovered from the Kanosh Shale at Fossil Mountain, Utah, are dominated by operculate acritarchs and cryptospores with minor smaller acritarchs. The present findings add new data to the largely incomplete knowledge of Ordovician acritarch assemblages from Laurentia, up to now known only from very few localities in North America. These populations contain some species in common with acritarchs from the Canning and Georgina basins in Australia and with assemblages from China; they indicate a Middle Ordovician (Dapingian-Darriwilian) age. The assemblage is lacking many typical marine acritarchs of this age, which, in combination with some cryptospores, is probably reflecting the likelihood of freshwater influence in the Kanosh Basin. This observation is congruent with previous interpretations of the depositional setting of the Kanosh Shale as a shallow water lagoon that supported the deposition of carbonate hardgrounds.Four new taxa are described: Busphaeridium vermiculatum n. gen., n. sp.; Digitoglomus minutum n. gen., n. sp.; Turpisphaera heteromorpha n. gen., n. sp.; and Vermimarginata barbata n. gen., n. sp. In addition, the abundance of operculate forms has enabled the revision and a new emendation of the genus Dicommopalla and clarification of the “opalla” complex. We also propose new and revised suprageneric taxa that emphasize inferred biological differences among acritarch genera. The Sphaeromorphitae subgroup is emended to include forms lacking sculptural elements. Two new informal subgroups are proposed: the Superornamenti and the Operculate Acritarchs. Cryptospores are abundant throughout the sections studied and they appear to be more closely related to the late Cambrian Agamachates Taylor and Strother than to Darriwilian and younger Ordovician cryptospores from Gondwana.

Diversity patterns and palaeoecology of benthic communities of the Kanosh Formation (Pogonip Group, Utah, western USA)

“…Stratigraphic age control is provided by the occurrence of trilobites noted herein and described and established by others (Hintze 1953;Adrain et al 2012). One of the most characteristic trilobites of Zone M, Kanoshia kanoshensis is not observed above the sandstone and shale member, which supports previous placements of the Zone M -Zone N transition within this member (Adrain et al 2012;Edwards and Saltzman 2014;Vecoli et al 2015). This agrees with the statement of Hintze (1973) that zone M extends "from the base of the Kanosh to about 300 feet" (91.4 m) of the formation.…”

“…Strata of the Pogonip Group of western Utah, and eastern and central Nevada have long been acknowledged to represent an exquisite archive of Lower and Middle Ordovician marine life in western Laurentia (Hintze and Davis 2003). As one of the most fossiliferous and lithologically conspicuous units of the Pogonip Group, the Kanosh Formation received considerable attention expressed in studies on stratigraphy (Hintze 1953;Hintze 1973;Fortey and Droser 1996;Adrain et al 2012), palaeoecology and taphonomy (Wilson et al 1992;Li and Droser 1999;Boyer and Droser 2003), and systematic palaeontology of various fossil groups including trilobites (Hintze 1953;Adrain et al 2012), brachiopods (Ulrich and Cooper 1938;Jensen 1967), bryozoans (Ernst et al 2007), echinoderms (Sumrall and Sprinkle 2015), and palynomorphs (Vecoli et al 2015). Despite these efforts, no prior palaeoecological analysis exists that examined major macroinvertebrate groups together (few samples of the Kanosh are presented by Finnegan and Droser (2005) though).…”

Revisiting the Great Ordovician Diversification of land plants: Recent data and perspectives

“…Such cryptospore occurrences are from Gondwanan localities of Libya (e.g., Gray et al, 1982;Gray, 1985Gray, , 1988Richardson, 1988), Saudi Arabia (e.g., Strother et al, 1996Strother et al, , 2015, Argentina (e.g., Rubinstein and Vaccari, 2004;Rubinstein et al, 2010), Algeria (e.g., Spina, 2014), as well as from microcontinents on the periphery of Gondwana, including Avalonia (e.g., Wellman, 1996;Steemans, 2001), Armorica sensu lato (e.g., Vavrdová, 1984Vavrdová, , 1988Vavrdová, , 1989Vavrdová, , 1990) and Turkey (e.g., Steemans et al, 1996). Ordovician cryptospores were also found in localities from the Laurentia palaeocontinent (e.g., Gray and Boucot, 1971;Gray, 1991;Vecoli et al, 2015), from Australia (i.e., the northernmost part of Gondwana located in the northern hemisphere; e.g., Foster and Williams, 1991), China (e.g., Wang et al, 1997;Yin and He, 2000), Baltica (Vecoli et al, 2011;Badawy et al, 2014) and Siberia (Raevskaya et al, 2016).…”

How far did feedback between biodiversity and early diagenesis affect the nature of Early Palaeozoic sea floors?

“…His material came mainly from the Upper Ordovician (early Katian; Trentonian/Caradoc) Simcoe Group of southern Ontario and the laterally equivalent Trenton and Black River Groups in northern and central New York State, and the Middle Ordovician (late Arenig, Dapingian–Darriwilian; Vecoli et al . ) Kanosh Formation of southwest Utah. He noted a low diversity of early cementation styles in the hardgrounds found in storm‐influenced facies, and that hardgrounds were effectively absent from shoal settings (cf.…”