Another piece in the monkey puzzle

The primate fossil record is uneven, and substantial gaps remain. One such gap is the divergence of cercopithecoids (Old World monkeys) and hominoids (apes and humans) within Old World higher primates (Catarrhini). This event was previously thought to have occurred sometime during the early Oligocene– early Miocene interval in Afro-Arabia, but the discovery of a new stem catarrhine in western Saudi Arabia narrows that gap. The Saudi specimen, dated to the mid-Oligocene around 29 million to 28 million years ago, shows no crown catarrhine specializations other than the presence of a tubular ectotympanic, suggesting that the divergence of Old World monkeys and apes happened after that date. The cover shows the anterior view of the cranium, which has its lateral incisors, canines and broad molars in situ. The size of the cranium indicates a mediumsized primate, weighing between 15 and 20 kilograms in body mass. [Letter p. 360 | Nature Video »]