Palaeogeography, Palaeoclimatology, Palaeoecology 183 (2002) 103^133 www.elsevier.com/locate/palaeo Circum-Mediterranean Oligo^Miocene biogeographic evolution ^ the gastropods’ point of view Mathias Harzhauser a, Werner E.Piller b;Ã, Fritz F.Steininger c a Naturhistorisches Museum Wien, Geologisch-Pala«ontologische Abteilung, Burgring 7, A-1014 Vienna, Austria b Institut fu«r Geologie und Pala«ontologie, Universita«t Graz, Heinrichstrasse 26, A-8010 Graz, Austria c Naturmuseum Senckenberg, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany Received 2 April 2001; accepted 24 October 2001 Abstract Based on studies in Iran (Qom Basin, Esfahan^Sirjan Basin, Zagros Mountains), in Turkey (Mut and Sivas basins), in the Mesohellenic Basin, and in northeastern Egypt, a new palaeobiogeographic concept for the Oligocene and Miocene in the circum-Mediterranean area with special emphasis on the distribution patterns of gastropod faunas is presented.A very strict biogeographic terminology is proposed to avoid the common fusion of geographic, faunistic and geodynamic terms in the palaeontologists’ jargon.Our main interest focuses on the affinities and the faunistic interactions between the early ‘Mediterranean’ and the early ‘Indo-Pacific’ regions during the Oligo^Miocene. Especially the role of the early Indo-Pacific faunas as the mythic centre of origination of Early Neogene European mollusc faunas, as often vaguely indicated in the literature, is critically evaluated.This leads to the establishment of a Mediterranean^Iranian Province and a Western Indian^Eastern African Province as palaeobiogeographic subunits of the Western Tethys Region during the Oligocene.Due to major geodynamic and related biogeographic changes in the Early Miocene the Western Tethys Region no longer existed and was replaced by the Proto-Mediterranean^Atlantic Region.For the area of the Paratethys the palaeobiogeographic unit Danubian Province, which includes the Proto- Caspian Subprovince, is proposed.Furthermore, the underrated transatlantic communication of the Oligo^Miocene nearshore mollusc faunas is demonstrated.Altogether this paper is a contribution to the discussion on the bio- geographic concepts, classification and nomenclature in palaeontology as initiated by Westermann [Palaeogeogr.Pa- laeoclimatol.Palaeobiogeogr.158 (2000) 1^13; 163 (2000) 49^68]. ß 2002 Elsevier Science B.V.Allrights reserved. Keywords: biogeography; gastropods; Indo-Paci¢c; Mediterranean; Paratethys; Atlantic 1. Introduction tral Europe has been produced (e.g. Ho«rnes, 1856; Bellardi, 1872^1890; Ho«rnes and Auinger, During the 19th and 20th centuries a large da- 1879^1891; Sacco, 1890^1904; Cossmann and taset for Cenozoic gastropods from the Western Peyrot, 1909^1934).This led to an early under- Mediterranean, the European Atlantic and Cen- standing of Eocene to Miocene biogeography of this area.In an eastern direction, however, infor- mation concerning the Eastern Mediterranean * Corresponding author. and the Middle East was scanty.Gastropods E-mail address: [email protected] (W.E. Piller). were documented as rare byproducts during inves- 0031-0182 / 02 / $ ^ see front matter ß 2002 Elsevier Science B.V. All rights reserved. PII: S0031-0182(01)00464-3 PALAEO 2816 31-5-02 Cyaan Magenta Geel Zwart 104 M. Harzhauser et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 183 (2002) 103^133 tigations of regional geology.Due to the strong biogeographic entities, was thus severely ham- preservational bias related to the predominantly pered by a palaeontological no man’s land span- studied calcareous facies, the mollusc studies fo- ning the entire eastern Mediterranean and the cused mainly on oysters and pectinids (Douglas, connecting Tethyan seaway.Therefore, modern 1927, 1928).On the other hand, scattered and palaeobiogeographic interpretations of late Te- inhomogeneous data on Eocene to Miocene gas- thyan mollusc faunas (Piccoli, 1984; Piccoli et tropod faunas from Pakistan, Somalia, Kenya, al., 1986, 1991) were usually based on the well- Madagascar, Southern India, Burma, and Java studied Northern Italian and Pakistanian faunas. (Noetling, 1901; Martin, 1914^1915, 1916^1917, The vast area in-between was taken into consid- 1921^1922; Davies, 1923; Vredenburg, 1925^ eration only cursorily since their poorly docu- 1928; Collignon and Cottreau, 1927; Cox, mented and low diversity faunas were considered 1930a; Azzaroli, 1958) allowed a glance at the to be of little palaeobiogeographic value. composition and evolution of the early Indo- To close this gap we focused on this poorly West Paci¢c faunas.The comparison of Mediter- studied area.Detailed investigations of Oligocene ranean and Asian faunas, representing two major and Early Miocene sections in the Greek Meso- Fig.1.Geographic location of the herein reported Oligocene and Early Miocene gastropod faunas.The faunas from Iran, Turkey and Greece form the base for the present study, whereas the low diversity and poorly preserved faunas from Egypt and Oman are only supplementary.Additionally, the position of some selected European and Asian reference faunas is indicated.Among these, the Italian and Pakistanian gastropod faunas turned out to represent the cornerstones for biogeographic considerations in the circum-Mediterranean area. PALAEO 2816 31-5-02 Cyaan Magenta Geel Zwart M. Harzhauser et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 183 (2002) 103^133 105 hellenic Basin, the Turkish Mut and Sivas basins to Lattin’s subregion whilst the subrealm of Wes- and especially the Iranian Qom and Esfahan^Sir- termann (2000b) seems to be more or less synon- jan basins (Fig.1) yielded a high number of shal- ymous to ‘region’ of most biogeographers.Long- low marine gastropod faunas.Hence, the faunistic hurst (1998) unites the provinces in biomes. gap in the Eastern Mediterranean was ¢lled and However, the geographic and biogeographic data from Iran, which is identi¢ed as key area boundaries of the modern shallow-water subdivi- between Mediterranean and Paci¢c faunas, are sions are more or less the same for all authors. available for the ¢rst time.Based on these data Recently, biogeographic principles and the de- a new concept of the palaeobiogeography of the nomination of units and their hierarchical ranking Oligocene and Early Miocene Western Tethys can were discussed by Westermann (2000a,b).In his be developed. ‘Rules of Biogeographic Nomenclature’, Wester- The main interest focussed on the dawn of the mann (2000a) proposes a strict use of biogeo- fauna of the Mediterranean^Iranian Province.Its graphic terms, with emphasis on homonyms and birth from the Oligocene faunal-stock of the vast synonyms as well as stability throughout geolog- Tethys Realm is outlined, and the in£uence of the ical time.Westermann (2000a) tries to establish Proto-Indo-West Paci¢c Region on the Early the general term ‘biochore’ for all biogeographic Miocene gastropod faunas of the Iranian Qom units.The term ‘biochore’ is, however, highly con- Basin and the faunas of the Mediterranean area troversially used: for many neontologists ‘bio- is evaluated. chore’ has a strong ecological component without geographic restrictions (e.g. biochores are grass- land, forest, and desert) and even for palaeontol- 2. Biogeographic basics ogists such as Lehmann (1996) ‘Biochorion’ is a small area within a biotope (e.g. a treetrunck or a A summary of the various concepts and hierar- carcass).Thus a biochore in modern biology ^ chies in biogeography is given in Sedlag and Wei- especially in botany ^ is a subdivision of the bio- nert (1987), who recommend a terminology corre- cycle which contains a group of biotopes that re- sponding to Lattin (1967).According to these semble one another.This diverging use of ‘bio- authors the usually rather vaguely used term chore’ is based on the unclear translation of the ‘province’ should be con¢ned to a part of a sub- Greek bio-‘MgbYc’ as living-‘space’ instead of liv- region.The latter term corresponds largely to the ing-‘place’.Therefore, not to prolong the confu- term ‘province’ as used by Woodward (1856) and sions, we prefer ‘biogeographic unit’ instead of Hedgpeth (1957).Finally, the subregions are the term biochore. united into large biogeographic units ^ the re- Westermann (2000a,b) recommends the ranks gions. Superrealm, Realm, Subrealm, Province, and Sub- A strict de¢nition of the various biogeographic province as valid hierarchical categories for the units based on percentages of endemisms is pre- de¢nition of his biochores.The term region is sented by Kau¡mann (1973) and Kau¡mann and for informal use only.We believe, however, that Scott (1976).According to this de¢nition a realm the well-established and widely used term ‘region’ is characterised by more than 75% endemism, a should be obligatory and not replaced by an op- region comprises 50^75%, a province 25^50%, a tional term as ‘Subrealm’.Therefore, in this paper subprovince 10^25% and ¢nally an endemic centre the terms province and region are mainly used reaches 5^10% endemism. sensu Briggs (1995).In contrast, we follow Wes- Generally, the term province as proposed by termann (2000a) in his proposed rule, that the Sedlag and Weinert (1987) is accepted by modern replacement of names is acceptable under certain biogeographers including Briggs (1995), Long- conditions, e.g. extreme biochore expansion or hurst (1998), and Westermann (2000a,b).None- contraction, exceptional geologic change at re- theless the classi¢cation of higher ranks is in a gional or global