Article: Conodonts from the Ordovician Shinnel Formation, Southern Uplands, Scotland
Howard A. Armstrong
The Shinnel Formation is dominated by over 2 km of quartzose sandstones. It crops out between the Fardingmullach and Orlock Bridge faults, Northern Belt of the Southern Uplands, and is of mid Ashgill age. The interbedded and distinctive Tweeddale Member (previously the Wrae Limestone and Tweeddale lavas) comprises debris flow deposits with clasts of limestone which yield a diverse and abundant conodont fauna, including Pygodus anserinus, Baltoniodus variabilis, Periodon aculeatus, Protopanderodus varicostatus, Spinodus spinatus, Eoplacognathus lindstroemi, Strachanognathus parvus and coniform species; an assemblage considered to be of P. anserinus Biozone (late Llanvirn (Llandeilian) to early Caradoc (Aurelucian)) age. These conodont faunas are similar to those from the upper Stinchar Limestone from Girvan to the north-west. The deep or cool water, predominantly prioniodontid and panderodontid, conodont fauna is described systematically for the first time. Emended apparatus plans are proposed for Pygodus anserinus, Protopanderodus varicostatus and Strachanognathus parvus.