The Early Cretaceous palynological successions record one of the earliest waves of angiosperm radiation in several low-latitude localities, including the Arabian Plate. The palynological analysis of 59 core and cuttings samples from the late Barremian-early Aptian Biyadh and Shu'aiba formations, offshore Saudi Arabia, reveals remarkably high angiosperm diversity. These Early Cretaceous angiosperms inhabited northeastern Gondwana together with a diverse flora that also included bryophytes, lycopodiopsids, ferns, conifers, and other gymno-sperms. A review of the dispersal capacity of this Gondwanan flora suggests that most mainland taxa had potentially colonized the carbonate islands and island arc archipelagos on both sides of the Neotethys Ocean.Two models are postulated to explain the late Barremian-early Aptian radiation of angiosperms. During sea -level lows, angiosperms would be easily dispersed to carbonate islands contiguous to northeastern Gondwana. Early birds and flying reptiles acted as the main dispersal agents for the early flowering plants, together with a diverse set of abiotic factors. The sub-aerial exposures of oceanic seamounts would serve as stepping-stones for early birds and flying reptiles, allowing a two-way dispersal of angiosperm propagules to distant volcanic islands. During sea-level highs, angiosperm gene flow between the mainland pool and the island inhabitants would be severely impeded because of the drowning of the coastal regions, many carbonate islands, and seamounts, thus promoting insular allopatric speciation and adaptive radiation. During these periods of geographical isolation, the remaining emergent Neotethyan archipelagos would act as 'insular centers of diversification' generating angiosperm island endemics, which in turn would be dispersed to the mainland during the following sea-level lows. Additionally, the gene flow of early aquatic angiosperms colonizing the scattered water bodies on north-eastern Gondwanan wetlands would be limited during sea-level lows, turning these sites into 'wet centers of diversification'.

A palynological analysis of core and cuttings samples from successions assigned to the Biyadh Formation of Saudi Arabia in the Arabian Gulf (eastern margin of northern Gondwana) revealed diverse and well-preserved palynological assemblages including bryophyte and fern spores, gymnosperm and flowering plant pollen, dinocysts, and acritarchs. Palynological data corroborates earlier geological and stratigraphic models, indicating a ?late Barremianearly Aptian age. The fluctuations of dinocyst abundance and diversity proved extremely useful to detect fine-scale sea-level changes in carbonate platforms with episodic terrigenous inputs. In agreement with current understanding of dinocyst paleoenvironmental distribution trends, Cribroperidinium and Aptea? vannophora are restricted to inner neritic/?fluvial-influenced settings, while Spiniferites and Trichodinium have been confirmed as more open marine water (middle/outer neritic) indicators. The composition of the terrestrial assemblages is dominated by fluvially-transported spores, mainly released by ferns and probable tree ferns. The overall floral composition is considered to reflect a seasonal, humid, climate punctuated by episodic droughts. Recurrent increases in abundance of wind-pollinated cheirolepid and Araucariaceae pollen, observed in assemblages otherwise characterized by low dinocyst content, are interpreted to represent sea-level falls and basinward expansion/migration of conifer-dominated coastal vegetation. The abundance of the dinocysts Cepadinium variabilis and Pseudoceratium nohrhansenii sp. nov., previously recorded at higher latitudes, is interpreted to reflect the invasion of cooler/colder water masses, confirming a significant ?latest Barremian/early Aptian global cold episode, possibly related to the OAE1a event. The following new dinocyst taxa are described: Pseudoceratium nohrhansenii sp. nov. and Protobatioladium alhajrii sp. nov.

Early flowering plants constituted a minor component of the Early Cretaceous conifer- and fern- dominated flora. However, their pollen provides a rich, albeit incomplete, record of the group's early evolutionary history. Palynological analysis of Barremian-lower Aptian successions from the Biyadh and Shu'aiba formations in the Arabian Gulf reveals remarkably high angiosperm diversity. While Chloranthaceae, magnoliids, monocots, eudicots, and other "basal" groups represent the bulk of flowering plants, pollen with uncertain affinities is also a significant component of the angiosperm assemblage. Analysis of the palaeobiogeographic distribution of angiosperm pollen during the late Barremian-early Aptian allowed us to discern three groups of angiosperms. The first group, including Clavatipollenites, produced pollen with a near-cosmopolitan distribution. The second group, including Stellatopollis, had a somewhat restricted distribution in northern Gondwana and western Laurasia. The pollen distribution of the third group, which includes Dichastopollenites, is restricted to central and/ or northeastern Gondwana. These varied patterns of palaeobiogeographical spread of early angiosperms reflect different migration and colonisation abilities. When compared with coeval palynological successions from other Gondwanan localities, the composition and diversity of the Arabian angiosperm assemblages support early hypotheses on the radiation of angiosperms that identify northeastern Gondwana as one of the most important centres of angiosperm diversification.The following new taxa are described: Splitipollis gen. nov., Splitipollis reticulatus sp. nov., Tucanopollis doylei sp. nov., Pennipollis spinosus sp. nov., Clavamonocolpites woodii sp. nov., and Retimonoporites arabiensis sp. nov.

Biosteering in Saudi Arabia is successful in achieving greater contacts with the Khuff C Member pay zones. The procedure supports Underbalanced Coiled Tube Drilling (UBCTD) and has been applied since 2008 to improve gas and condensate recovery from development wells in the Upper Permian Khuff C carbonate of Saudi Arabia. Multiple laterals are drilled by re-entry of the mother-bore with the objective of maintaining the well-path trajectory within selected porous layers. This method of drilling permits the drill string to re-enter the mother-bore of older development wells and new infill wells. The drill commences a lateral path through a window milled in the mother-bore casing and has the advantage of rapid adjustment to the inclination and trajectory as well as enabling continued gas and condensate production while drilling. As wireline logging during slim-bore, coiled-tubing drilling is confined to the gamma tool, which follows the bit by approximately 30 ft, the only "real-time" source of stratigraphic control is provided by micropaleontological analysis, up to two hours ahead of the gamma data. Controlled drilling prohibits the use of rate of penetration (ROP) as an accessory stratigraphic guide. For instance, the use of water as a drilling medium enables cuttings to be received with a lag time of 10 to 20 minutes from 12,000ft, depending on the degree of gas contribution. By comparing the micropaleontology of cuttings samples with those recorded in a cored offset well, the stratigraphic position can be determined within 2 ft vertical thickness. Caving is minimal due to the sliding and non-rotational drilling method. This information enables the well-path trajectory to be monitored, as it approaches the planned layer, and real-time instructions provided to the directional driller whenever deviation from the targeted porosity layer is detected. This process is termed biosteering. The Upper Permian microfossils are typically less than 0.5 mm in size and can be well-preserved in small cuttings samples. In addition, the morphology of foraminifera, calcareous algae, bryozoa and other microfossils are sufficiently varied to enable confident species identification in randomly oriented thin-sections. Although of predominantly shallow marine origin, Khuff C depositional environments were highly varied leading to a succession of vertical microfacies variations that provide calibration with biofacies analyzed from cuttings in the "laterals". As the Khuff C environment also varied across the region, no single microfacies scheme can be applied to all wells in the development area and necessitated establishment of a local reference zonation for each biosteered well. Such a local reference section is based on high-resolution micropaleontological and petrographic analysis of cored wells located as close as possible to the intended lateral trajectory. Knowledge of the micropaleontological diversity, abundance and good preservation in all post-Permian carbonate reservoirs provides the potential for biosteering in similar reservoirs in the Middle East and circum-Tethyan regions.

Analysis of Silurian graptolite assemblages from 1017 sample horizons in 132 cores (from 65 boreholes) through the Qusaiba Member, Qalibah Formation of Saudi Arabia, provides a refined graptolite biostratigraphy for the Arabian Peninsula comparable in its resolution to that from the British Isles and the Czech Republic. Over 150 graptolite species characterize 11 biozones from the lowermost Rhuddanian lubricus Biozone to the lower Telychian guerichi Biozone, with sub-zonal resolution for several intervals. Graptolite biozonal boundaries and the Rhuddanian Aeronian and Aeronian Telychian stage boundaries can be placed with high precision. Detailed analysis of graptolite spatial distribution suggests persistent depth-stratified marine assemblages across the Silurian palaeo-Arabian Plate. Near-surface-dwelling assemblages probably occupied the mixed-layer of Silurian oceans, enabling colonization of shallow shelf environments. They are low-diversity (1-2 species) assemblages characterized by Neodiplograptus, Coronograptus, Neolagarograptus and Stimulograptus species and often are preserved in strata with extensive shelly faunas. Deeper marine assemblages are of higher diversity (up to 15 species per horizon), and are characterized by dorsally curved or helically coiled species of Spirograptus, Demirastrites, Lituigraptus, Rastrites and Torquigraptus. Recognition of depth-stratified graptolite assemblages provides an important tool for establishing palaeo-basin topography and water depth at the time of sedimentary deposition. At the species level, the graptolite assemblages of Saudi Arabia are remarkably similar to contemporaneous faunas from peri-Gondwanan Europe and, from the middle Rhuddanian onwards, also to the Avalonian and Laurentian Llandovery graptolites of the UK.