Lower Silurian (Rhuddanian) brachiopods from the Argentine

Abstract

A brachiopod fauna dominated by Hindella crassa (J. de C. Sowerby), and also including an indeterminate pseudolinguloid, Leangella (Leangella) america nov. sp., Eoplectodonta (Eoplectodonta) duplicata (J. de C. Sowerby), Fardenia sp., Glyptorthis vidari (Baarli)., Dolerorthis plicata (J. de C. Sowerby), an indeterminate giraldiellid, Dalmanella sp., and Stegerhynchus pusillum (J. de C. Sowerby), is described from the La Chilca Formation exposed at Mogotes Azules, San Juan Province, Argentina. The age of the fauna is Early Silurian (Llandovery: Rhuddanian) and it is compared with other Rhuddanian brachiopod faunas both from Gondwana and elsewhere. The brachiopod faunas of Gondwana, despite their relatively low diversity, had much in common with those from Laurentia and Avalonia-Baltica, and heralded the cosmopolitanism that prevailed for all of the first half of the Silurian.