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The trilobite assemblage of the Declivolithus Fauna (lower Katian, Ordovician) of Morocco: a review with new data

Published online by Cambridge University Press:  15 January 2024

Sofia Pereira*
Affiliation:
Universidade de Coimbra, Centro de Geociências, Departamento de Ciências da Terra, Coimbra, Portugal
Isabel Rábano
Affiliation:
CN Instituto Geológico y Minero de España - CSIC, Ríos Rosas 23, 28003 Madrid, Spain
Juan Carlos Gutiérrez-Marco
Affiliation:
Instituto de Geociencias (CSIC, UCM) and Área de Paleontología GEODESPAL, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, José Antonio Novais 12, 28040 Madrid, Spain
*
*Corresponding author.

Abstract

Intense commercial exploitation of fossils in the famous El Qaid Errami area in the last 20 years has led to the discovery of the interesting Declivolithus Fauna in the Moroccan Anti-Atlas. This unusually large trinucleid trilobite, described originally from the Czech Republic, is the most conspicuous element of an assemblage mainly occurring in the Bofloss locality, a local biofacies development of pelagic mudstones and sandstones cropping out in a structurally isolated place in the Tizi n'Ounfite area. Here we revise this Declivolithus Fauna trilobite assemblage from Morocco, increasing the known trilobite diversity from four to 11 species: Ulugtella? biformis n. sp., Selenopeltis cf. S. vultuosa, Phacopidina quadrata, Eudolatites cf. E. bondoni, Prionocheilus cf. P. verneuili, Nobiliasaphus cf. N. kumatox, Cyclopyge cf. C. rediviva, Symphysops stevaninae, Heterocyclopyge sp., Dionide sp., and Declivolithus alfredi. The new data and the very good preservation of specimens in sandstones, clarify the specific identity of previously reported taxa. Although the stratigraphical correlation of the fossiliferous levels remains problematic, it probably corresponds to the upper part of the Lower Ktaoua Formation or to the lower half of the Upper Tiouririne Formation. Most taxa support previous assignment of the Moroccan assemblage to the late Berounian (ca. early Katian, Ka2), although a middle Berounian (ca. Sa2–Ka1) age cannot be excluded. Most of the identified species are known from the Czech Republic (eight out of 11), showing that the strong faunal link between Morocco and the Czech Republic still existed during the Late Ordovician, being stronger than the link with the coeval Ibero-Armorican domain faunas.

UUID: http://zoobank.org/3e6e55c7-168d-4008-98ba-38a795581ca3

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Copyright
Copyright © The Author(s), 2024. Published by Cambridge University Press on behalf of Paleontological Society

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