Middle Ordovician (Darriwilian) radiolarians from the Crawford Group, Scotland

Abstract

A diverse assemblage of moderately well-preserved radiolarians occurs in the Ordovician cherts of the Crawford Group in the Southern Uplands terrane of the Scottish borders. A total of 8 genera and 11 species are described. Taxa present correlate to the Middle Ordovician Pygodus anserinus biozone. Key species identified include: Proventocitum procerulum, Inanigutta gansuensis, Inanigutta sp. cf. I. complanata, Inanibigutta sp. cf. I. verrucula, Inanibigutta sp. cf. I. pinglianensis, ?Inanibigutta inconstans, ?Inanihella penrosei, Haplentactinia armillata, ?Oriundogutta ramificans and Syntagentactinia sp. A new species Haplotaeniatum albaensis is introduced here and described on the basis of details of skeletal architecture observed using microcomputed tomography, demonstrating the potential of this technique as a tool for improving the understanding of radiolarian taxonomy.

Late Sandbian (Sa2) radiolarians of the Pingliang Formation from the Guanzhuang section, Gansu Province, China

“…The response of radiolarians mainly included structural adaptations, such as development of a pylome that was initiated by Darriwilian time in Triplococcus, Westernbrookia, and Protopylentonema n. gen., and successfully passed on to Late Ordovician Kalimnasphaera, Borisella, and Sandbian members of Protopylentonema n. gen. By Late Ordovician time, bandage- Perera and Aitchison-Late Sandbian radiolarians from Pingliang Formation, China type shell wall-bearing antygoporids and aspiculids of the Middle Ordovician were mostly replaced by solid, thick skeleton-bearing inaniguttids (Kalimnasphaera, Geminusphaera n. gen., Inanibigutta, Inanigutta, and Oriundogutta), increasing the robustness of the skeleton and adapting to both shallow-and deep-water facies. Although radiolarian discoveries are usually subjected to strong preservation and collection biases, which shadows true relative species abundances, many studies conducted for Ordovician radiolarians confirm the dominating occurrence of inaniguttids Wang, 1993;Danelian and Clarkson, 1998;Danelian and Floyd, 2001;Maletz and Bruton, 2008;Maletz et al, 2009;Noble and Webby, 2009;Kachovich and Aitchison, 2020;Perera et al, 2020). This indicates that the Inaniguttidae were the most successful family to diversify during the GOBE.…”

“…Inanigutta gansuensis also had been reported in two studies where SEM images were used for descriptions (Pouille et al, 2013;Perera et al, 2020). Both studies mention broken spines and do not report any six-spined specimens.…”

“…Journal of Paleontology:1-27Etymology.-From the Latin 'implexa' symbolizing the 'entangled. 'Remarks.-Micro-CT reveals that layers of H. implexa are not as widely spread as those of Haplotaeniatum albaensis Perera, Aitchison, and Nothdurft, 2020 (seePerera et al, 2020). All the spherical Haplotaeniatum species encountered from the Darriwilian Shundy Formation(Pouille et al, 2014) are larger in outer diameter compared to H. implexa.…”

Middle Ordovician (middle Darriwilian) Archaeospicularia and Entactinaria (radiolarians) from the Table Cove Formation, Piccadilly Quarry, Newfoundland, Canada

“…Ordovician, upper Dapingian, Akzhal Mountains, Kazakhstan (Nazarov and Popov, 1980); Lower Ordovician, Spitsbergen (Fortey and Holdsworth, 1971); Lower Ordovician, Ballantrae Complex, Scotland (Aitchison, 1998); Middle Ordovician, Southern Uplands terrane, Hawkwood Burn, Scotland (Perera et al, 2020).…”

“…Radiolarian faunas have been reported from Ordovician strata globally from North and South America, Spitsbergen, Scotland, Russia, China, and Australia (see Danelian et al, 2017 and references therein). Documentation of Middle Ordovician (Darriwilian) radiolarians has been presented from Newfoundland (Kachovich and Aitchison, 2020), Argentina (Maletz et al, 2009), Kazakhstan (Nazarov, 1975; Nazarov et al, 1977; Nazarov and Ormiston, 1993; Pouille et al, 2013, 2014b), Scotland (Danelian and Clarkson, 1998; Danelian, 1999; Danelian and Floyd, 2001; Danelian et al, 2013; Perera et al, 2020), and China (Li, 1995; Buckman and Aitchison, 2001; Yi et al 2018).…”