A slope-faced, big-toothed creature from the distant past has led scientists to recalibrate the ancient evolutionary split between apes and Old World monkeys.
A partial skull found in western Saudi Arabia suggests that those two primate groups split between 29 million and 24 million years ago, the fossil's discoverers say. A 2004 analysis of DNA from living apes and monkeys in Africa and Asia had estimated an earlier divergence, between 34.5 million and 29.2 million years ago.
An intriguing mosaic of features on the newly unearthed fossil, which dates to between 29 million and 28 million years ago, suggests that it predates a common ancestor that gave rise to hominoids--a primate lineage that includes apes and humans-and the monkeys of Africa, Asia and Europe. A team led by anthropology graduate student Iyad Zalmout of the University of Michigan in Ann Arbor reports the find in the July 15 Nature, assigning the skull to a new primate genus and species, Saadanius hijazensis.
"This is a wonderful discovery, a real missing link that fills in a gap in our understanding of the timing and pattern of anatomical change involved in the evolution of Old World monkeys and apes," remarks anthropologist John Fleagle of Stony Brook University in New …