GUADALUPIAN BRACHIOPODS FROM TUNISIA AND TURKEY: SYSTEMATICS AND PALAEOBIOGEOGRAPHIC IMPLICATIONS

In the present PhD Thesis two Guadalupian brachiopod faunas are described respectively from succession cropping out at Djebel Tebaga de Medenine, S Tunisia, and from the Guadalupian lower-middle part of the Pamuçak Formation at Çürük Dağ, Antalya (Turkey). The study is based on collection already available in Dipartimento di Scienze della Terra “A. Desio”, Milano and on material newly collected by the writer. The taxonomic study and description of the brachiopod collections, based on the observations of the macro- and micro- external and internal morphological features, with critical comparison with the available literature, has allowed the determinations of 1260 specimens at generic and specific level into 68 species (including the undetermined ones) and 42 genera; they belong to orders Productida, Orthotetida, Orthida, Rhynchonellida, Athyridida, Spiriferida and Terebratulida for the Tunisian fauna; to the orders Productida, Orthotetida, Orthida, Rhynchonellida, Athyridida, Spiriferida, Spiriferinida and Terebratulida for the Turkish fauna. Five new species and two new genera are identified and established and are in press in two publications (Verna et al. in press a, b). Several brachiopod taxa are revised and their diagnostic characters better identified in order to make their determination, up to now problematic, easier (i.e. Squamularia Gemmellaro, 1899 and Permophricodothyris Pavlova). In the course of this research, the Gemmellaro collection of brachiopods from Sosio, Sicily has been also revised in part. The stratigraphic range of the Tunisian brachiopods is consistent with the Wordian- early Capitanian age suggested by the associated fusulinids and conodonts which are the tools on which the Permian Time Scale is based, allowing the correlation of the International (Global) with the Tethyan regional scale, particularly for the Guadalupian part. The age of the Turkish brachiopods coming from the lower middle part of the Pamuçak Formation is mid-Roadian to Capitanian, based on conodonts, fusulinids and already published data (Angiolini et al. 2007). The brachiopod record at Çürük Dağ section (Turkey) has implications to understand the pattern of the end-Guadalupian biotic crisis which is here represented by highly diversified pre-crisis assemblages terminating rather abruptly and being followed by Lopingian brachiopod taxa which show a significantly lower biodiversity. The last part of this study consists of a palaeobiogeographic analysis based on the comparison of the brachiopod faunas from Tunisia and Turkey originally collected and studied by the writer, with coeval ones described in several publications in the recent and distant past coming from the successions of Sosio (Sicily), Oman, N Iran, Central Afghanistan, Karakorum, Salt Range, SE Thailand. This palaeobiogeographic analysis aims to test the palaeogeographic reconstructions, independently derived from palaeomagnetic data and to derive the possible dispersal pattern of the brachiopod genera during the Guadalupian. The methods used for this analysis are cluster analysis and principal coordinate analysis (PCO), based on the similarity indices of Jaccard and Simpson applied to a presence/absence data matrix (taxa per geographic areas) of the brachiopod genera coming from Tunisia, Turkey and the other faunal stations quoted above, using the software PAST (Hammer et al. 2001). The palaeobiogegraphic affinities of the analyzed faunal stations are in agreement with the Guadalupian palaeogeographic reconstruction based on palaeomagnetic data of Muttoni et al. (2009) and indicates a consistent degree of isolation of Tunisia and Sosio from the other regions and strong faunal links between Turkey and the Gondwanan margins, represented by Oman, Salt Range and S Thailand.