Early Ordovician (Arenig) brachiopods from volcaniclastic rocks of the Famatina Range, northwest Argentina

• Published in: Journal of Paleontology
• Main Author: Benedetto, Juan L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2003
• Subjects: Newfoundland
• Online Access: http://dx.doi.org/10.1017/s0022336000043614; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022336000043614

This paper constitutes the first monographical study of the rich brachiopod faunas from the Early Ordovician Suri and Molles Formations of the central Famatina Range, which form a nearly continuous, more than 2,000 m thick succession of fossiliferous clastic and volcaniclastic rocks. Conodonts from the brachiopod-rich levels of the upper third of the Suri Formation and Los Molles Formation indicate the upper part of the Oepikodus evae Biozone (mid-Arenig). The systematic study of brachiopod faunas reveals the presence of 22 species belonging to 19 genera, three of which are new. The new genera recognized are the orthid Suriorthis , the hesperonomiid Mollesella , and the rectostrophiid Trigonostrophia . The following 12 new species and subspecies are described and illustrated: the clitambonitoidean Tritoechia mollesensis the skenidioideans Crossiskenidium ? stelzneri and Skenidioides kayseri the orthoideans Paralenorthis suriensis, Paralenorthis riojanus brevis, Panderina ? ambigua, Productorthis angulensis, Hesperonomiella arcuata , and Monorthis transversa the plectorthoideans Ffynnonia famatinensis and Desmorthis ? bifurcata and the porambonitoidean Rugostrophia protoandina . Associated forms are Tritoechia sp., Pinatotoechia acantha Benedetto, 2001b; Protoskenidioides cf. revelata Williams, 1974; Hesperonomia orientalis Benedetto, 1998a; Paralenorthis riojanus (Levy and Nullo, 1973), Famatinorthis turneri (Levy and Nullo, 1973); and Camerella sp. Brachiopods from the Famatina Range display strong affinities with Welsh and Central Newfoundland, Maine and New Brunswick volcanic assemblages forming with them a statistically well defined Celtic cluster. Faunal evidence suggests that the Famatina volcanic belt continues northward into the western Puna belt.