Revison of an Atheloptic Visean Trilobite Association in the Moravian Karst (Czech Republic)

Abstract

Abstract:Recently two new trilobite occurrences were discovered during geological mapping of fossiliferous shales of the Březina Formation around the village of Březina in the Moravian Karst (Czech Republic). The newly discovered localities are extraordinary because of the unexpected occurrence of articulated trilobite exoskeletons associated with brachiopods including supporting spines. The new atheloptic association of Mississippian trilobites is described for the first time from the Moravian Karst.

The first lower Viséan trilobite association from limestone facies of the Moravian Karst and its relation to the sedimentary environment (Líšeň Formation, Czech Republic)

“…Rak et al (2012) determined various trilobite taxa from the Mokrá quarry, based on imperfectly preserved specimens which often makes determination difficult at the specific or even generic level (see note of Müller & Hahn 2018, p. 14;Hahn et al 2019, p. 85). Rak et al (2012) considered this association to be the youngest in the entire Březina Formation in the Moravian Karst and similar stratigraphic conclusion was published two years later (Rak et al 2014). We consider the trilobite association from the Mokrá quarry as probably the stratigraphically oldest in the Březina Formation.…”

“…species from the lower part of the Viséan (= Lower to Middle Viséan, ?or up to the lowermost Upper Viséan, cu IIγ-δ stage, see Fig. 1E) have only been described from the aleuropelitic facies of the Březina Formation (Chlupáč 1966(Chlupáč , 1969Kalvoda et al 2010;Weiner et al 2012;Rak et al 2014). In this paper, the first lower Viséan trilobite association from limestone facies of the Líšeň Formation is described and discussed.…”

“…This association is also close to the basinal shale association of Owens (1990). Owens (1990) expected similar settings for the upper Chadian (lower Viséan) atheloptic trilobite association from North Devon (SW England), which also closely resembles the trilobite association from Březina (Prentice 1967, Owens & Tilsley 1995, Rak et al 2014. It can thus be reasonably assumed that Viséan trilobite associations from Březina, Hranice na Moravě, Čelechovice, and probably also the valley of the Říčka brook (Chlupáč 1966(Chlupáč , 1969Weiner et al 2012;Rak et al 2014) represent a relatively distal basinal environment.…”

“…This species is associated with further taxa, such as smalleyed archegonids and blind weaniine trilobite Combewoodia (or formerly cystispinine, Hahn et al 2007 andHahn 2018). These associations are characterised by blind or smalleyed taxa (similarity with atheloptic assemblage sensu Fortey & Owens 1987; see Weiner et al 2012, Rak et al 2014. Another lower Viséan trilobite association from the shale successions of the Březina Formation was recorded in the valley of the Říčka brook near BrnoLíšeň, where somewhat largereyed archegonids [Archegonus (Phillibole) cf.…”

“…Trilobite localities previously assigned to the lower part of the Viséan were only known in aleuropelitic shale successions of the Březina Formation. These localities include Březina, valley of the Říčka brook, Zbrašov near Hranice, and Čelechovice (Chlupáč 1966(Chlupáč , 1969Weiner et al 2012;Rak et al 2014). With the exceptions of a borehole (Chlupáč 1966) and a surface locality (Weiner et al 2012) in the valley of the Říčka brook, presence of often abundant blind cystispinine trilobite Spinibole (Spinibole) olgae Chlupáč, 1966 is typical in these localities.…”