The Khos-Nelege River section of the Ogon’or Formation: a potential candidate for the GSSP of Stage 10, Cambrian System

A potential GSSP for the base of the uppermost Cambrian stage, coinciding with the first appearance of Lotagnostus americanus at Wa'ergang, Hunan, China

“…They include the widely distributed agnostoid Neoagnostus bilobus, and the polymerids Skljarella hunanensis and Macropyge (Promacropyge) ciliensis. S. hunanensis and M. (P.) ciliensis are so far recognised only from NW Hunan, but similar species, some of which may be synonymous, are known from other localities in China (Guihzou, Xinjiang and Zhejiang), Kazakhstan, Siberia, Tasmania and Sweden (Yin & Lee 1978;Zhang 1981;Apollonov et al 1984;Xiang & Zhang 1985;Lu & Lin 1989;Bao & Jago 2000;Terfelt & Ahlgren 2007;Lazarenko et al 2011).…”

“…Landing et al (2011) argued that the stratigraphic level of the type material of L. americanus is uncertain as it was known only from boulders in Quebec, Canada. However, in some localities, for example, in Siberia, South Kazakhstan and South China (Ergaliev 1983;Peng et al 2001;Lazarenko et al 2011), well-constrained occurrences of the species demonstrate that the FAD of the species consistently lies about two-thirds of the way up from the base of the Furongian Series. This is a convenient position for delineating the uppermost stage if the series is to be divided into three stages.…”

Lower to Middle Ordovician trilobite faunas along the Ural border of Baltica

“…Outside of Baltoscandia, Nyaya appears in the Nyaian Regional Stage in the lowest Ordovician of Siberia (Rozova 1968(Rozova , 1977Ogienko 1974Ogienko , 1984Gorovtsova & Semenova 1977; for the latest correlation of the Cambrian-Ordovician boundary see Lazarenko et al 2011). Together with Tersella it is known also from the lowest Ordovician in the Kuznetsk Alatau (Petrunina 1973(Petrunina , 1990, and from the Tremadocian Sokoli Stage of Pay-Khoy ( Fig.…”

“…The earliest asaphids, Promegalaspides and Niobe, which originate in Cambrian of Siberia or Baltoscandia ( Fig. 3; Lazarenko et al 2011) also arrive in the Uralian side of Baltica during the early Ordovician. The poorly known Hystricurus is shared between Siberia and the Urals (Balashova 1961).…”

“…The eulomid Kujandaspis (including species of Ketyna; see for discussion on taxonomy in Rushton et al 2002) is known from the upper Cambrian of the Kazakh terranes (Ivshin 1956, Apollonov & Chugaeva 1983, from Severnaya Zemlya (Rushton et al 2002) and the Kulyumbe and Chopko rivers in the Siberia Plate ( Fig. 3; Rozova 1968, Varlamov et al 2006, Lazarenko et al 2011) that possibly faced to the north of the Baltica Plate at that time (Fig. 1A;Cocks & Torsvik 2002).…”