Campanian-Maastrichtian foraminiferal stratigraphy and palaeoenvironment of the Lower Tar Member in the Wadi Tar section, Western Sirte Basin (Libya)

Upper Campanian-Maastrichtian sections on the western flank of the Hun Graben in the Western Sirte Basin (WSB) are displaying two major type facies based on the foraminiferal assemblages. The first one indicates open-marine to outer-shelf conditions, and is represented by numerous bathy-pelagic planktonic foraminiferal species referable to the Radotruncana calcarata, Globotruncana aegyptiaca and the lower part of the Gansserina gansseri Zone (all late Campanian).The second type facies indicates an inner-shelf environment and is represented in the middle-upper part of the Gansserina gansseri Zone (early Maastrichtian) and Racemiguembelina fructicosa (late Maastrichtian) dominated by epi-pelagic planktonic and large benthic foraminifers. Large benthic foraminiferal index species Siderolites calcitrapoides Lamarck and Omphalocyclus macroporus (Lamarck) occur in abundance by the middle-late Maastrichtian. Correlation between planktonic foraminiferal zonation and large benthic foraminiferal zonation is given. An open-marine to outer-shelf environment passed into shallower marine conditions during the late Campanian-early Maastrichtian to late Maastrichtian, then a slight deepening and again shallowing is noticed

A large abelisauroid theropod dinosaur from the Early Cretaceous of Libya

Despite increasingly intensive paleontological sampling, Cretaceous terrestrial vertebrates from continental Africa remain relatively poorly known, frustrating efforts to characterize paleoecosystems in the region, as well as the paleobiogeography of the southern continents during this interval. Here we describe the partial skeleton of a large-bodied theropod dinosaur from the Early Cretaceous (early Aptian, ∼125-120 Ma) of Libya. The specimen consists of associated elements (two incomplete dorsal vertebrae, a proximal caudal centrum, a partial proximal caudal neural arch, the distal right femur, and the mostly complete right tibia) and is referable to the widespread ceratosaurian clade Abelisauroidea. The discovery adds to the growing record of abelisauroids from mainland Africa, and firmly establishes the presence of the clade on the continent prior to its final separation from South America. Indeed, the age of the Libyan theropod predates or is penecontemporaneous with the accepted timing of fragmentation of most major Gondwanan landmasses, supporting the hypothesis that abelisauroids could have dispersed throughout the southern continents before land connections between these areas were severed. Moreover, the considerable size of the Libyan form challenges assertions that abelisauroids were ecologically subordinate to basal tetanuran theropods in Early and middle Cretaceous paleoenvironments of Gondwana. © 2010 The Paleontological Society