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Significance The primate subfamily Cercopithecinae represents the most diverse and successful living Old World primate group, with a current distribution throughout Africa and Asia. However, how and when these monkeys dispersed out of Africa is not well understood. This paper is significant in its description of a ∼6.5–8.0 million-y-old fossil guenon from Arabia representing the earliest cercopithecine (and only guenon) yet known outside of Africa. Furthermore, this specimen extends the guenon fossil record by at least 2.3 million y and may represent the earliest known cercopithecine as well. Because Old World monkeys appear to have dispersed out of Africa sometime during the Late Miocene, the Arabian fossils also have implications for dispersal scenarios in Old World monkey biogeography and evolution.

Many living vertebrates exhibit complex social structures, evidence for the antiquity of which is limited to rare and exceptional fossil finds. Living elephants possess a characteristic social structure that is sex-segregated and multi-tiered, centred around a matriarchal family and solitary or loosely associated groups of adult males. Although the fossil record of Proboscidea is extensive, the origin and evolution of social structure in this clade is virtually unknown. Here, we present imagery and analyses of an extensive late Miocene fossil trackway site from the United Arab Emirates. The site of Mleisa 1 preserves exceptionally long trackways of a herd of at least 13 individuals of varying size transected by that of a single large individual, indicating the presence of both herding and solitary social modes. Trackway stride lengths and resulting body mass estimates indicate that the solitary individual was also the largest and therefore most likely a male. Sexual determination for the herd is equivocal, but the body size profile and number of individuals are commensurate with those of a modern elephant family unit. The Mleisa 1 trackways provide direct evidence for the antiquity of characteristic and complex social structure in Proboscidea.

(previously known as the Western Region) comprises much of the area of Abu Dhabi Emirate west of the city of Abu Dhabi and bears the only known late Miocene terrestrial fossil biota from the entire Arabian Peninsula. Driving along the Abu Dhabi-As Sila' highway, which runs parallel to the Gulf coast and connects the United Arab Emirates to Saudi Arabia, one encounters a landscape of low dunes to the south, and sabkha (supratidal salt flats) and the sea to the north. Interspersed on both sides of the highway are low-lying jebels (hills), at most rising about 60 m above the surrounding terrain. 111ese jebels are capped by a resistant gypsum-anhydrite-chert bed that produces characteristic table-top forms, or mesas. 111e sediments of these flat-topped jebels have been formally described as the Baynunah Formation (Whybrow 1989) and are composed mainly of reddish fine-to medium-grained sands of dominantly fluvial origin, along with brown and g reen silts, alternating sand-carbonate sequences, gypsum, and fine intraformational conglomerates. Several horizons within the Baynunah Formation bear fossils, either body parts or traces, of vertebrate, invertebrate, and plant taxa (figures 27.1 and 27.2). From the sites of Rumaitha in the east to Jebel Barakah in the west, and from the sites of Shuwaihat in the north to Jaw AI Dibsa in the south, the area across which the Baynunah Formation is exposed forms a long eastwest trending quadrangle measuring 180 x 45 km, covering 8100 km 2 (figure 27.3). Interspersed within this area are over two dozen documented sites from which fossil remains have been collected over three decades. 111ese fossils include remains ofhippopotamus, giraffes, crocodiles, rodents, turtles, catfish, ratites, machairodont felid, and hyaenids, as well as bivalves, gastropods, and fossil wood. The Baynunah Formation records a time when a perennial river supported a rich ecosystem in what is now a hyperarid part of the world. By way of biochronology, the Baynunah fossil fauna is estimated to be between 8 Ma and 6 Ma (Whybrow and Hill 1999). No other terrestrial fossil sites of late Miocene age are known from the remainder of the Arabian Peninsula. The Baynunah fauna, then, represents the sole sample available to chart the biotic continuity between late Miocene Arabia and neighboring contemporaneous fossil sites in Asia (e.g., Siwaliks, Marageh), the Mediterranean (Pikermi, Samos), and Africa (Sahabi, Toros-Menalla, Lothagam, Tugen Hills). Since the publication of a monographic treatment of the Baynunah fossils (Whybrow and Hilll999), renewed fieldwork activities have brought new light to elements of the Baynunah fossil fauna. 1l1is chapter summarizes the latest knowledge on the fossil biota of the late Miocene Baynunah Formation. HISTORY OF EXPlORATION The first indications of the presence of vertebrate fossils from AI Gharbia came with the explorations of oil geologists working in the 1940s (Hill, Whybrow, and Yasin

Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than "Thryonomys" asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6-8 Ma).