The animal species depicted in the rock art of Shuwaymis, Saudi Arabia, provide a record of Holocene climatic changes, as seen by the engravers. Of 1903 animal engravings, 1514 contained sufficient detail to allow identification with confidence. In addition, the stratigraphy of the engravings and the depiction of domesticates provide a broad chronological framework that allows a division into images created during the Holocene humid phase and animals represented after the onset of desert conditions. Despite the large sample size, only 16 animal species could be identified, which represents an extraordinarily narrow species spectrum. Comparison with the scarce faunal record of the Arabian Peninsula shows that all larger animals that are thought to have been present in the area were also depicted in the rock art. The contemporaneous presence of at least four large carnivores during the Holocene humid phase suggests that prey animals were abundant, and that the landscape consisted of a mosaic of habitats, potentially with thicker vegetation along the water courses of the wadis and more open vegetation in the landscape around them. Community Earth System Models (COSMOS) climate simulations show that Shuwaymis was at the northern edge of the African Summer Monsoon rainfall regime. It is therefore possible that Shuwaymis was ecologically connected with southwestern Arabia, and that an arid barrier remained in place to the north, restricting the dispersal of Levantine species into Arabia.

a b s t r a c tFreshwater availability is critical for human survival, and in the Saharo-Arabian desert belt repeated fluctuations between aridity and humidity over the Quaternary mean the distribution of freshwater was likely a primary control upon routes and opportunities for hominin dispersals. However, our knowledge of the spatio-temporal distribution of palaeohydrological resources within Arabia during MideLate Pleistocene episodes of climatic amelioration remains limited. In this paper we outline a combined method for remotely mapping the location of palaeodrainage and palaeolakes in currently arid regions that were formerly subject to more humid conditions. We demonstrate the potential of this approach by mapping palaeochannels across the whole Arabian Peninsula, and palaeolakes and marshes for select regions covering c. 10% of its surface. Our palaeodrainage mapping is based upon quantitative thresholding of HydroSHEDs data, which applies flow routing to Digital Elevation Model (DEM) data, while our palaeolake mapping uses an innovative method where spectral classification of Landsat Thematic Mapper (TM) imagery is used to detect palaeolake deposits within endorheic (closed) basins, before modelling maximum lake extents by flooding the basin to the level of the elevation of the highest detected deposit. Field survey in the Nefud desert and the Dawadmi and Shuwaymis regions of Saudi Arabia indicates accuracies of 86% for palaeodrainage mapping, and 96% for identifying former palaeolake basins (73% accuracy of classification of individual deposits). The palaeolake mapping method has also demonstrated potential for identifying surface and stratified archaeological site locations, with 76% of the surveyed palaeolake basins containing archaeological material, including stratified Palaeolithic archaeology. Initial examination of palaeodrainage in relation to archaeological sites indicates a relationship between mapped features and previously recorded Palaeolithic sites. An example of the application of these data for period-specific regional palaeohydrological and archaeological reconstructions is presented for a region of Northern Saudi Arabia covering the southern Nefud desert and adjacent lava fields.

The current paucity of Pleistocene vertebrate records from the Arabian Peninsula-a landmass of over 3 million km 2-is a significant gap in our knowledge of the Quaternary. Such data are critical lines of contextual evidence for considering animal and hominin dispersals between Africa and Eurasia generally, and hominin palaeoecology in the Pleistocene landscapes of the Arabian interior specifically. Here, we describe an important contribution to the record and report stratigraphically-constrained fossils of mammals, birds and reptiles from recent excavations at the site at Ti's al Ghadah in the southwestern Nefud Desert. U series and combined US-ESR analyses of Oryx sp. teeth indicate that the assemblage is Middle Pleistocene in age and dates to ca. 500 ka. The identified fauna is a biogeographical admixture that consists of likely endemics and taxa of African and Eurasian affinity and includes extinct and extant (or related Pleistocene forms of) mammals (Palaeoloxodon cf. recki, Panthera cf. gombaszogenis, Equus hemionus, cf. Crocuta crocuta, Vulpes sp., Canis anthus, Oryx sp.), the first Pleistocene records of birds from the Arabian Peninsula (Struthio sp., Neophron percnopterus, Milvus cf. migrans, Tachybaptus sp. Anas sp., Pterocles orientalis, Motacilla cf. alba) and reptiles (Varanidae/Uromastyx sp.). We infer that the assemblage reflects mortality in populations of herbivorous animals and their predators and scavengers that were attracted to freshwater and plant resources in the inter-dune basin. At present, there is no evidence to suggest hominin agency in the accumulation of the bone assemblages. The inferred ecological characteristics of the taxa recovered indicate the presence, at least periodically, of substantial water-bodies and open grassland habitats.