Among the Orbitolininae, Palorbitolina lenticularis (Blumenbach) is a common facies marker in Upper Barremian Lower Aptian shallow water Mesogean deposits and was hitherto ascribed to specifi c, but contrasting paleoenviron ments within the carbonate platform facies suites. The Albacete-Prebetic area (SE Spain) illustrates a model in which the Palorbitolina facies spread over the whole platform system. The development of the Palorbitolina sediments coincided with a transgressive trend at the end of an important terrigenous period. This model could also be applied to similar Middle Cretaceous "Orbitolina" facies.

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Shallow-water organisms recovered from drilling four guyots in the western Pacific (from the southern Marshall Islands to the Japanese Seamounts) allow the recognition of changes in bioprovinces through time. The Tethyan low-latitude bioprovince characterizes the early Aptian worldwide. In the late Albian, however, shallow-water floral and f aunal assemblages from the drilled guyots, although predominantly composed of cosmopolitan forms, yielded few elements with an areal distribution more restricted to either the Caribbean-central American region or the Mediterranean, suggesting that two bioprovinces had already differentiated at low latitude at that time. During the late Campanian-Maastrichtian, the guyots' area was under the influence of the Caribbean bioprovince, but foraminifer assemblages also include some Mediterranean elements, suggesting that colonization occurred both westward and eastward. In the latest Paleocene-early middle Eocene, the direction of colonization reversed, with prevalent migration from the Mediterranean toward the Pacific.

This work provides a new ammonite age-calibration of the rudistid limestones of the Urgonian-type Provence carbonate platform (Southeast France) based on sampling along three ~200 km-long platform-to-basin transects and re-examination of historical collections. Ammonite key findings indicate that the first rudistid platform stage (including the Agriopleura and requieniid-monopleurid beds) develops and spreads northward through the Toxancyloceras vandenheckii-Gerhardtia sartousiana zones interval (lower upper Barremian). This stage is interrupted by the tectonically-induced deepening of the southern Provence domain during the Imerites giraudi Zone while the northern regions records the massive deposition of Palorbitolina-Heteraster beds. Recovery of the rudistid carbonate system is illustrated by the development of caprinid-bearing rudistid limestones in the North Provence domain through the Martelites sarasini Subzone (lower Martelites sarasini Zone, uppermost Barremian), which shows a bidirectional progradation toward the South Provence and Vocontian basins. The 2 caprinid-bearing limestones terminate at a short-term exposure and are overlain by cherty-oobioclastic deposits spanning the Pseudocrioceras waagenoides Subzone (upper M. sarasini Zone) to the lower Deshayesites forbesi Zone. A regional-wide flooding of the study area is illustrated by the abrupt change to a marl-dominated regime occurring in the upper D. forbesi Zone. Compared to the previous datings, the Barremian/Aptian boundary should be relocated in the lower part of the post-caprinid, cherty-oobioclastic deposits although its precise level cannot be fixed due to the lack of a continuous ammonite record. Ammonite age-calibration of the surrounding Urgonian rudistid platform series is discussed and gives evidence of a comparable twofold demise of the peri-Vocontian rudistid biota during the uppermost Barremian. Accordingly, the link between the final demise of the peri-Vocontian rudistid biota and the onset and/or culmination of the mid-early Aptian Oceanic Anoxic Event (OAE) 1a should be reconsidered.