Biodiversity, Distribution and Patterns of Extinction of the Last Odontopleuroid Trilobites During the Devonian (Givetian, Frasnian)
Geol. Mag. 144 (5), 2007, pp. 777–796. c 2007 Cambridge University Press 777 doi:10.1017/S0016756807003779 First published online 13 August 2007 Printed in the United Kingdom Biodiversity, distribution and patterns of extinction of the last odontopleuroid trilobites during the Devonian (Givetian, Frasnian) ∗ RAIMUND FEIST & KENNETH J. MCNAMARA† ∗Laboratoire de Paleontologie,´ Institut des Sciences de l’Evolution, Universite´ Montpellier II, Cc 062, Place E. Bataillon, 34095 Montpellier, France †Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK (Received 18 September 2006; accepted 22 February 2007) Abstract – Biostratigraphical ranges and palaeogeographical distribution of mid-Givetian to end- Frasnian odontopleurids are investigated. The discovery of Leonaspis rhenohercynica sp. nov. in mid-Givetian strata extends this genus unexpectedly up to the late Middle Devonian. New material of Radiaspis radiata (Goldfuss, 1843) and the first koneprusiine in Britain, Koneprusia? sp., are described from the famous Lummaton shell-bed, Torquay, Devon. New taxa of Koneprusia, K. serrensis, K. aboussalamae, K. brevispina,andK. sp. A and K. sp. B are defined. Ceratocephala (Leonaspis) harborti Richter & Richter, 1926, is revised and reassigned to Gondwanaspis Feist, 2002. Two new species of Gondwanaspis, G. dracula and G. spinosa, plus three others left in open nomenclature, are described from the late Frasnian of Western Australia. A further species of Gondwanaspis, G. prisca, is described from the early Frasnian of Montagne Noire. Species of Gondwanaspis are shown to possess a number of paedomorphic features. A functional analysis suggests that, unlike other odontopleurids, Gondwanaspis actively fed and rested with the same cephalic orientation. The sole odontopleurid survivors of the severe terminal mid-Givetian biocrisis (‘Taghanic Event’) belong to the koneprusiine Koneprusia in the late Givetian and Frasnian, and, of cryptogenic origin, the acidaspidine Gondwanaspis in the Frasnian.
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