of the recorded assemblages in several fauna1 groups of NW Europe and Tethys are observed. The uppermost Levesquei Subzone thermal peak has only been recognized in the deposits of the section located in Central Spain and coincides with a positive o l3 C excursIOn.

The Early Toarcian mass extinction event represented the most important Mesozoic and Cenozoic turnover of the population of brachiopods and severely affected other benthic fauna. Two main hypotheses have been proposed to explain the synchronous and global mass extinction: an oceanic anoxic event or a warming episode. To test both hypotheses, the dynamics of the brachiopod assemblages below and above the extinction boundary are analyzed and compared with the seawater paleotemperature variations, calculated from the δ 18 O data recorded in belemnite rostra. Five sections from Northern and Central Spain, well dated with ammonites, have been selected for this study. The sections show no indication of sedimentary breaks and contain abundant brachiopods, which have been grouped into four assemblages. The changes observed in the brachiopod assemblages show a close correlation with the changes in the seawater paleotemperatures. The oldest assemblage (assemblage 1) coincides with a cooling interval recorded to have taken place in the latest Pliensbachian. Paleobiogeographical reconstruction shows that this assemblage was distributed at paleolatitudes between 30 and 45°N, with a preference for relatively cool waters. With the rise of temperatures that took place during the earliest Toarcian Tenuicostatum Zone, assemblage 1 was substituted by assemblage 2, which composed of different species of the same genera but considerably restricted to the warmer waters of lower paleolatitudes, between 28 and 35°N. Coinciding with the rapid and pronounced increase in seawater temperature, recorded at the Tenuicostatum-Serpentinum zonal boundary, all of these brachiopod species disappeared in the studied localities, marking clearly the extinction boundary. Predominant southward currents through the Laurasian Seaway precluded the possible migration of the brachiopods to cooler northern waters. The brachiopods' disappearance is independent from the oxygenation degree of the sea bottom, and therefore the rapid warming seems to be the most plausible cause of the mass extinction. After the extinction event, the recovery of the brachiopods was uneven. Subsequent to a brief pause, recovery was rapid in Central Spain and in other southern areas of Western Tethys, whereas in northern Spain and in the whole of Europe north of the French Central Massif, brachiopods did not recover until the Mid to Late Toarcian times.

Abstract. One of the main controversial themes in palaeoclimatology involves elucidating whether climate during the Jurassic was warmer than the present day and if it was the same over Pangaea, with no major latitudinal gradients. There has been an abundance of evidence of oscillations in seawater temperature throughout the Jurassic. The Pliensbachian (Early Jurassic) constitutes a distinctive time interval for which several seawater temperature oscillations, including an exceptional cooling event, have been documented. To constrain the timing and magnitude of these climate changes, the Rodiles section of the Asturian Basin (Northern Spain), a well exposed succession of the uppermost Sinemurian, Pliensbachian and Lower Toarcian deposits, has been studied. A total of 562 beds were measured and sampled for ammonites, for biochronostratigraphical purposes, and for belemnites, to determine the palaeoclimatic evolution through stable isotope studies. Comparison of the recorded latest Sinemurian, Pliensbachian and Early Toarcian changes in seawater palaeotemperature with other European sections allows characterization of several climatic changes that are likely of a global extent. A warming interval partly coinciding with a δ 13 C bel negative excursion was recorded at the Late Sinemurian. After a "normal" temperature interval, with temperatures close to average values of the Late Sinemurian-Early Toarcian period, a new warming interval containing a short-lived positive δ 13 C bel peak, developed during the Early-Late Pliensbachian transition. The Late Pliensbachian represents an outstanding cooling interval containing a δ 13 C bel positive excursion interrupted by a small negative δ 13 C bel peak. Finally, the Early Toarcian represented an exceptional warming period, which has been pointed out as being responsible for the prominent Early Toarcian mass extinction.

Causes of the major mass extinction recorded during the Early Toarcian (Early Jurassic) are controversial. Many authors have concluded that the mass extinction is caused by the widespread oceanic anoxia derived from a postulated Early Toarcian Oceanic Anoxic Event (ETOAE), supposedly synchronous in all basins and global in extent. Another group of papers links the mass extinction with a major climate change that occurred synchronously with the mass extinction. The results of the study of five sections of the uppermost Pliensbachian and Lower-Middle Toarcian deposits, located in northern and central Spain are presented. Detailed ammonite-based biostratigraphy, coupled with stable isotope analysis of belemnite calcite and bulk carbonates, as well as total organic carbon (TOC) analyses have been performed in all sections. Records of the vertical distribution of mainly benthic fossils have been compiled in four of the studied sections. Results obtained in the Spanish outcrops have been compared and correlated with other European sections. The excellent mutual relation between the patterns of the Early Toarcian progressive warming and the concomitant progressive losses of species evidences a cause-and-effect relationship between the increase of temperature and the mass extinction. From an uppermost Pliensbachian cooling interval, warming started at the Lower Toarcian Tenuicostatum Zone. Increase of average seawater palaeotemperature is associated with a progressive and substantial drawdown in the number of species of nektonic, planktonic and benthic organisms, representing the extinction interval. A prominent increase in seawater temperature occurred around the Lower Toarcian Tenuicostatum-Serpentinum zonal boundary. Average temperatures at the Serpentinum Zone increased about 7 °C, marking the extinction boundary. The high temperatures continued during the Middle Toarcian Bifrons Chronozone, representing the repopulation interval. The anoxia linked to the postulated ETOAE cannot be the responsible for the mass extinction, because it has been synchronously recorded in the oxygenated environments of many European and Northern African platforms. Deposition of laminated organic-rich black shale facies, above 5 wt.% TOC indicating anoxic environments, was mostly confined geographically to the Western Europe Euxinic Basin, and mainly deposited after the extinction event, during the interval of faunal recovery.

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