Original article Early Carboniferous (Mississippian) ammonoid biogeography § Dieter Korn a, *, Alan L. Titus b , Volker Ebbighausen c,1 , Royal H. Mapes d , Milan N. Sudar e a Museum fu ¨r Naturkunde, Leibniz Institute at the Humboldt University Berlin, Invalidenstrabe 43, 10115 Berlin, Germany b Grand Staircase-Escalante National Monument, 190 East Center Street, Kanab, UT 84741, USA c Engstenberger Ho ¨he, 51579 Odenthal, Germany d Department of Geological Sciences, Ohio University, Athens 45701, USA e Department of Paleontology, Faculty of Mining and Geology, University of Belgrade, Kamenicˇka 6, PO Box 62, 11000 Belgrade, Serbia 1. Introduction The quantitative study of Carboniferous biogeography is a relatively recent endeavour. With their pioneering study, Ross and Ross (1985) initiated the first detailed biogeographic study using various fossil groups in their analysis. It was found that during Early Carboniferous time, barriers such as mountain chains and oceanic trenches increasingly separated equatorial shelf areas. The result was increasing provincialism of the invertebrate faunas, as demonstrated for ammonoids (Korn, 1997a). Most previous ammonoid biogeographic studies have focused only on the Late Vise ´an and Early Serpukhovian, i.e. the time when the Variscan Orogeny caused a major reconfiguration of the shelf areas. Kullmann (1962) discussed in a qualitative way the biogeographic patterns of late Early Carboniferous ammonoids, pointing out that the Namurian ammonoid faunas of the Cantabrian Mountains show much closer affinities to the assemblages from the South Urals than those from the North Variscan (British Isles, Central Europe). Quantitative analyses of Palaeozoic ammonoids and Carbonif- erous fossils in general have only rarely been published, in contrast to Permian brachiopods (Shen and Shi, 2000, 2004; Powell, 2007; Shen et al., 2009), Permian bivalves (Biakov and Shi, 2010), Triassic ammonoids (e.g., Brayard et al., 2006, 2007, 2009) and Jurassic- Cretaceous ammonoids (e.g., Cecca et al., 2005; Dommergues et al., 2009). In those studies it was shown that latitudinal differences played an important role in the distribution of faunas. After near complete extinction near the Devonian-Carbonifer- ous boundary, the Ammonoidea experienced a rapid radiation at the beginning of the Carboniferous. Two major clades separate at the beginning of the Carboniferous (Korn and Ilg, 2011):  The very diverse order Goniatitida (approximately 1200 Early Carboniferous species);  The much less diverse order Prolecanitida (approximately 140 Early Carboniferous species). The evolution of these two lineages in the various regions allows for a biogeographic analysis of the Early Carboniferous ammonoids. Both clades differ significantly in the evolution of conch characters:  The Early Carboniferous members of the order Goniatitida are generally characterised by a stable number of suture elements, consisting of a simple or subdivided external lobe as well as simple adventive, lateral, umbilical, and internal lobes. At the same time, the order Goniatitida produced a large number of different conch shapes and shell ornament. Conch geometry is also rather variable through ontogeny; Geobios 45 (2012) 67–77 A R T I C L E I N F O Article history: Received 6 December 2010 Accepted 23 November 2011 Available online 26 December 2011 Keywords: Carboniferous Ammonoidea Biogeography Cluster analysis Non-metric multidimensional scaling A B S T R A C T Cluster analyses and non-metric multidimensional scaling of ammonoid assemblages from six successive Early Carboniferous time intervals (two Tournaisian, Vise ´ an, and Serpukhovian) show that increasing provincialism is the main biogeographic trend through the period. While the assemblages from the Tournaisian to the early Late Vise ´ an are globally similar in the tropical occurrences, dissimilarities appear in the middle Late Vise ´ an and become pronounced in the latest Vise ´ an, Pendleian, and Arnsbergian. From the latest Vise ´ an, two major biogeographic realms are recognisable. A north- western realm consists of the four North Variscan regions (Rhenish Mountains, North England, South Portugal, and Moroccan Meseta) as well as the American Midcontinent and the Antler Foreland Basin. The second realm includes the South Urals, which is the most diverse region and thus has an isolated position, as well as the Jadar Block of Serbia, the Cantabrian Mountains of Spain, the Anti-Atlas of Morocco, and the Saoura Valley of Algeria. ß 2012 Elsevier Masson SAS. All rights reserved. § Corresponding editor: Pascal Neige. * Corresponding author. E-mail address: dieter.korn@mfn-berlin.de (D. Korn). 1 yJune 3rd, 2011. Available online at www.sciencedirect.com 0016-6995/$ – see front matter ß 2012 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.geobios.2011.11.013