“…A short-lived drop in seawater temperature around the Callovian-Oxfordian transition has been identified using the oxygen isotope composition of shark tooth enamel, belemnite rostra and bivalve shells from Tethyan and sub-Arctic domains [Dromart et al, 2003b;Brigaud et al, 2009;Price and Rogov, 2009;Nunn and Price, 2010]. Although the influence of local paleoceanic changes implying cool water influxes cannot be completely excluded [Wierzbowski and Rogov, 2011], other independent proxies support the climatic interpretation for a cooling trend: (1) palynological and clay mineral data indicating that continental air became markedly cooler in north Europe hinterlands [Abbink et al, 2001;Pellenard and Deconinck, 2006], (2) successive southward invasions of boreal ammonite families in the NW Tethyan domains [Thierry et al, 2006] and (3) a local CO 2 minimum [Royer et al, 2004] located at the MLJT in the proxy record of CO 2 . During the Callovian and Oxfordian periods, perturbations in the carbonate deposition pattern occur [Dromart et al, 2003a] as evidenced by shrinkage of the latitudinal extent of carbonate platforms followed by a general demise of carbonate platforms deposition.…”