Late Cambrian radiolarian faunas and biostratigraphy of the Cow Head Group, western Newfoundland

Abstract

Well-preserved Late Cambrian radiolarian faunas were recovered from carbonate rocks of the Cow Head Group of the Great Northern Peninsula of the island of Newfoundland, Canada. Several different faunal assemblages were recognized from three strata at Green Point, one from a stratum at Martin Point, and three from strata at Broom Point South in Gros Morne National Park. The faunas contain nine genera, five of which are new, and 33 species, all but two of which are new. The five new genera are Curvechidnina, Grosmorneus, Pararcheoentactinia, Ramuspiculum, and Subechidnina. Most of the genera belong to the families Archeoentactinidae, Echidninidae, Palaeospiculumidae, and Protoentactiniidae; a few taxa have an uncertain taxonomic position. Echidnina, whose taxonomic identity was uncertain, is shown to be a radiolarian.The diversity of each of these faunas is similar, but the difference in faunal compositions among the faunas examined is distinct. From this analysis, the Late Cambrian strata between Martin Point and Green Point can be more precisely correlated, and the previous correlation has been revised. With the recovery of the conodonts in this study, the provisionally placed boundary between the Franconian and Trempealeauan at Martin Point by earlier researchers is revised and positioned between unit 30 and unit 31.The biostratigraphic range of the co-occurring conodonts indicates that the youngest fauna described in this paper belongs to the Eoconodontus notchpeakensis Zone of late Trempealeauan age and that the other faunas (from Martin Point and Green Point) are of Franconian age.

The Beothuka terranova (Radiolaria) assemblage and its importance for the understanding of early Ordovician radiolarian evolution

“…The material looks similar to specimens of Palaeospiculum greenpointensis Won Jenner et al 1991Webby et al 2004Tucker & McKerrow, 1995Harland et al 1990 D. bifidus Biozone Little Port Complex Kozur, Mostler & Repetski, 1996Won & Iams, 2002 ?…”

“…The number of spines and size of the test are unknown. The material shows structural relationships to Parechidnina (see Won & Iams, 2002), especially in the development of the three-dimensional mesh formed from thin radial spines or bars and curved connecting bars, and is therefore included in the genus. B) contains forms with robust and short spines, usually not more than 110 µm long and 10 µm wide (Fig.…”

“…It is well known that radiolarians had a successful history already in the Cambrian, as diverse faunas have recently been described from Australia and western Newfoundland (Won & Below, 1999;Won & Iams, 2002), respectively. It is well known that radiolarians had a successful history already in the Cambrian, as diverse faunas have recently been described from Australia and western Newfoundland (Won & Below, 1999;Won & Iams, 2002), respectively.…”

Biomineralization and Evolutionary History

“…By the end of the Early Cambrian, however, faunas included recognizable stem group members of many extant phyla and classes ( Figure 5; Budd and Jensen 2000). Among protists, radiolarians first appear in Cambrian rocks (Dong et al 1997;Won and Below 1999;Won and Iams 2002), as do agglutinated, but not calcified foraminiferans (McIlroy et al 2001). Skeletons assigned to the dasyclad green algae have been reported from Cambrian carbonates in Siberia, but, by and large, algal skeletons are not a conspicuous feature of Cambrian rocks (Johnson 1966).…”

Earliest Arenig radiolarians from the Cow Head Group, Western Newfoundland

“…A SERIES of studies of Middle Cambrian to uppermost Tremadocian (lowermost Ordovician) radiolarians performed by Kozur et al (1996), Won and Below (1999), Won and Iams (2002), and Won et al (2005Won et al ( , 2007 has shown their gradual phylogenetic diversification. These pre-Arenigian radiolarians appear to have no phylogenetic relationship to Arenigian taxa.…”