É++rJ++F,46 ( igfJ ) : 483-488 ( 2007 + 6 F ) Acta Palaeontologica Sinica , 46 ( Suppl. ): 483-488 ( June, 2007 ) # + tr fi H t'R 4 $EJ\¿ll frt*/rfF/È SEtlE'fü ä ü2* Oive TINNI), Leho AINSA.ART),Tõnu MEIDLAT), Lars E. HOLMEP) l) Institute of Geology, university of rarh;, vanemuise 46, 51014, Tartu, Estonia<oive.Tinn@ut.ee> 2) Depafment ofEarlh Sciences, Palaeobiology, Villavägen 16, SE-75236 Uppsala, Sweden +84 f,åÈrfita,fùã(ô,3c)É.¡AIN,þ*HE.rE+,HtÈdtE+,+n+ffãx" hrF_rtEwafrtùi+ttaÐlt+&trwþ 4, IFfl/} M#4ff'l4tÃt\E4frÃluÃN4LttT¡tL&41tft" tlî:+W+EjtV+il1?iËâFËÉ!È9.tF.E'Ìc-È¡r.E%. +Ìb+FTpõ " h\!fr+.u, ¿q¿p'JfnlftõtEEt.Ez\ õ',c {ËÉ.¡1Érr. iEyÉTpãEl Ê85â$ã IIRÈ|LHX, +T& ã.ltËÞlx,+$EÌ+f Ëfi+Ê'¡rtil16fr4þXÉrÃ4r. Ð1ftÉliEyEEIÊÉâ r\+^^+W.ffiRffi+4rJ&t+,ltÉ.fiH¡n" XTä MJ 4 ++,1+ 5 tA fr . Ft t¡ã. rn w,Ft Þ Þ ru, v1 4q rrl ft ü H t+ Ì ^Efr n " XfiåiFJ itV+, -,h+rJÊ+tlPÈ., EfrAln R, HW2¿, ü,ry tu1 - F¡Æm2fiÆú ORDOVICIAI{ OSTRACOD DIVERSITY AND CARBON ISOTOPE CURVE IT{ GULLHÖGEN, S\ryEDEN Oive TINNI), Leho AINSAART),Tõnu MEIDLAT), and Lars E. HOLMERÐ l) Institute of Geology, university of rartu, vanemuise 46,51014,Tartu, Estonia<oive.Tinn@ut.ee> 2) Department ofEarth Sciences, Palaeobiology, Vllavägen 16, SE-75236 Uppsala, Sweden 1 INTRODUCTION fluctuations and biotic events (Brenchley et al., 1994; Ainsaar et a1.,1999).In the present study we are going to analyze ostracod diversity data in comparison with carbon isotope changes, in order to assess regional biodiversity trends more definitively. 2 GEOLOGICAL SETTING The Gullhögen quany, situated on the south-eastem slope of Mount Billingen in Västergötland, is one of the largest limestone quarries in Sweden (Text-fig. 1). The almost 70 meters thick exposed section ranges from the Upper Cambrian to the lowerpart ofUpper Ordovician (Holmer, 1989) (Text-fig. 2). However, due to the complex landscape and quarrying, the complete succession has to be pieced together from different parts of the quarry. The lowermost 20 meters of the measured Gullhögen section, the Lanna and Holen limestones, comprise mostly red, bedded wackestones. They are divided by a grey- coloured packstone layer, locally known as Täljsten. Faunal diversity pattems comprise manifold information. They involve evolutionary patterns, including taxonomical differentiation and temporal dynamics of higher taxa. Diversity studies within a single section carry a strong regional signal, associated with the evolution of the basin, transgressive-regressive cycles and displacement of the palaeocontinent at the global scale. Ostracods were one of those groups that appeared and diversified in the course of the Ordovician radiation. In the Baltoscandian palaeobasin, the start of carbonate sedimentation in the late Early Ordovician coincides with the appearance ofostracods in the fossil record (Tinn, 2002). Ordovician ostracods of Baltoscandia are taxonomically well studied, and are one of the most abundant and diverse fossil groups, that display unusually good preservation for Lower Palaeozoic microfaunas. Trends in stable carbon isotopic composition (ðt3C) have been found to be often associated with sea-level