The shelly fauna and biostratigraphy of the lower Cambrian (provisional series 2, stage 4) Evjevik Member, Ringstrand Formation in the Mjøsa area, Norway

Abstract

New, extensive fossil material collected in situ from the lower Cambrian Evjevik Member in the Mjøsa type area, southern Norway, allows a re evaluation of the faunal distribution and diversity of the 'Ornamentaspis' linnarssoni Zone. Described taxa include three holmiid, six ellipsocephalid and one eodiscoid trilobite in addition to five helcionelloid molluscs. A Holmia species with affinities to the Swedish H. lapponica is common in the Evjevik Member. Librigenae, thoracic segments and pygidia from the poorly known, but biostratigraphically important trilobite 'Ornamentaspis' linnarssoni (Kiaer, 1917) are documented for the first time. The species is redescribed and transferred to Ellipsocephalus. Helcionelloid molluscs are represented by Helcionella antiqua (Kiaer, 1917), Stenotheca norvegica (Resser, 1938), Mackinnonia puppis n. sp., Mackinnonia? sp. and Latouchella sp. These are similar to taxa reported from coeval strata at Gislövshammar in southern Sweden and may prove to have biostratigraphical potential. The Holmia kjerulfi Zone, the Ellipsocephalus linnarssoni Zone and the Comluella? scanica-Ellipsocephalus lunatus Zone are readily recognised in the Lower Allochthon of the Mjøsa area and are in this report treated as distinctive, successive zones. New illustrations are provided of the brachiopod Magnicanalis rotundata (Kiaer, 1917), together with the enigmatic fossil Mongolitubulus Missarzhevsky, 1977, recorded for the first time in Norway.

Mollusks from the upper Shackleton Limestone (Cambrian Series 2), Central Transantarctic Mountains, East Antarctica

“…Davidonia puppis Høyberget et al, 2015 is similar to Davidonia cf. D. corrugata but is much larger in size, up to 6.5 mm in length (Høyberget et al, 2015, p. 49), and has a less recurved apex (Høyberget et al, 2015, fig. 16, A-J).…”

“…Skovsted (2004) later placed the species in Davidonia due to the prominent lateral rugae with polygonal aragonite imprints. This reassignment leaves M. taconica and another species, M. puppis Høyberget et al, 2015, from the Cambrian Stage 4 Evjevik Member of the Ringstrand Formation Norway (Høyberget et al, 2015), as outliers within the genus, as they lack a parietal train.…”

Morphometric analysis of inter‐ and intraspecific variation in the Cambrian helcionelloid mollusc Mackinnonia

“…Of the characteristics listed in Table , the presence of rugae and a thickened apertural ridge seem to be the only ones that unite the genus Mackinnonia . The species Mackinnonia taconica (Landing & Bartowski, ) and Mackinnonia puppis Høyberget et al ., lack the parietal train common to other species, and are the only high, sub‐orthoconic members of the genus. M. taconica has a complex generic taxonomy, first placed in Stenotheca Hicks, (Landing & Bartowski ) before being removed and used as the type species of the genus ‘ Aequiconus ’ (Parkhaev in Gravestock et al .…”

Cambrian palaeoscolecids (Cycloneuralia) of southern Scandinavia

“…Correlation of lithostratigraphies at various sample localities following Nielsen & Schovsbo (, ) and Høyberget et al . (). Sample horizons indicated by stars.…”

“…The Skyberg Member belongs to the Ellipsocephalus lunatus Biozone and consists of about 7 m of greenish‐grey, monotonous mudrocks with a thin sandstone near the top of the unit (Nielsen & Schovsbo ; Høyberget et al . ). It is unconformably overlain by middle Cambrian shales of the Alum Shale Formation.…”