Early Devonian (Pragian) vertebrates from the northern Roberts Mountains, Nevada

Abstract

Fossil fish are poorly represented in middle Lower Devonian deposits of the western United States. Here we describe vertebrate microremains from mid-Pragian levels in the Kobeh Member, McColley Canyon Formation, central Nevada. The species diversity of the assemblages is low and dominated by the acanthodian Nostolepis costata Goujet, 1976. This species is found in older (late Lochkovian–early Pragian) deposits in France and Spain and mid-Pragian or slightly younger deposits in Saudi Arabia. This distribution suggests dispersal to the west from the Armorica terrane around the south of Laurussia to the Nevada region, and southeastward to Arabia, on the northern margin of Gondwana.

Vertebrate Microremains from the Pragian, Emsian and Eifelian of the Prague Basin (Czech Republic)

“…The scale also resembles an unnamed scale described by Burrow & Murphy (2016) from Nevada and even more the scales referred to C. comptus from the Eifelian to Givetian of North Queensland (Pomeroy 1996) but the type species differs by a more elongate crown.…”

“…The histology of scales was not studied due to the rarity of the specimens. The morphological terminology of scales is adopted from Burrow & Murphy (2016). Material descriptions are arranged stratigraphicaly.…”

“…This species in known from the upper Lochkovian to the lower Pragian of Spain (Wang, 1993) as well as Saudi Arabia (Burrow et al, 2006) and Nevada (Burrow & Murphy, 2016). A discussion about similarly shaped scales from other areas has been given by Burrow & Murphy (2016). They indicate that N. costata is a widespread species along the Gondwanan shore of the Rheic and Palaeotethys oceans, but also illustrate intricate taxonomy of similarly shaped scales.…”

“…They indicate that N. costata is a widespread species along the Gondwanan shore of the Rheic and Palaeotethys oceans, but also illustrate intricate taxonomy of similarly shaped scales. All scales from the Zlíchov Formation differ from the specimens figured by Burrow & Murphy (2016) by the spiny posterolateral edges but despite this difference and different age, the new formal name is not introduced. The Bohemian scales are rather similar to scales from the Jawf Formation of Saudi Arabia (Burrow et al, 2006), especially by the uneven posterolateral edges of the crown, which resemble the spiny edges of the Bohemian scales.…”

“…The scales are also similar to the scales of Nostolepis costata (Goujet, 1976). This species in known from the upper Lochkovian to the lower Pragian of Spain (Wang, 1993) as well as Saudi Arabia (Burrow et al, 2006) and Nevada (Burrow & Murphy, 2016). A discussion about similarly shaped scales from other areas has been given by Burrow & Murphy (2016).…”