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Saadanius
''Saadanius'' is a genus of fossil primate dating to the Oligocene that is closely related to the common ancestor of the Old World monkeys and apes, collectively known as catarrhines. It is represented by a single species, ''Saadanius hijazensis'', which is known only from a single partial skull tentatively dated between 29 and 28 mya (million years ago). It was discovered in 2009 in western Saudi Arabia near Mecca and was first described in 2010 after a comparison with both living and fossil catarrhines.
''Saadanius'' had a longer face than living catarrhines and lacked the advanced frontal sinus (airspaces in the facial bones) found in living catarrhines. However, it had a bony ear tube (ectotympanic) and teeth comparable to those of living catarrhines. The discovery of ''Saadanius'' may help answer questions about the evolution and appearance of the last common ancestors of Old World monkeys and apes.
==Discovery==
''Saadanius'' is known from a single specimen, the holotype, named "SGS-UM 2009-002", stored in Jeddah, Saudi Arabia, at the Paleontology Unit of the Saudi Geological Survey (SGS). Its type locality, or the place it was discovered, was on top of an oolitic ironstone fossil bed of the middle Shumaysi Formation located in the southwest corner of Harrat Al Ujayfa, in western Saudi Arabia, close to Mecca. The specimen was discovered in February 2009 by paleontologist Iyad Zalmout, who had traveled to the region to search for ancient whale and dinosaur fossils. While looking for dinosaur fossils in an area that, according to the maps he was working from, contained rock layers that dated to the Cretaceous (145–66 mya), Zalmout found the jawbone of a hippo-like creature, called an anthracotheriid (a close relative of whales and hippos), which dated to Eocene or Oligocene. This indicated that the rock layers were much younger than what was dated on the maps. The following day, he noticed fossil teeth, which he immediately recognized as those of a primate. Zalmout emailed a photo of the teeth to paleontologist Philip D. Gingerich, with whom he was working as a postdoctoral fellow. Gingerich, an expert on ancient primates and whales, confirmed that it was indeed a primate. Due to a tight schedule, Zalmout had to leave the exposed fossil embedded in the rock for the next few days because collecting it would require days of work. The fossil was soon recovered by a joint expedition involving the SGS and the University of Michigan.
The fossil was not formally described until 2010 when its discovery was announced in the journal ''Nature''. The fossil was dated to about 28 or 29 million years ago based on comparisons of fossils of anthracotheriids and paenungulates (members of the group that includes elephants and hyraxes) found nearby with fossils from similarly aged African deposits. However, the date has yet to be confirmed by other dating techniques. The genus name, ''Saadanius'', comes from the Arabic word, ''saadan'' ((アラビア語:سَعدان)), which is the collective term for apes and monkeys. The species name, ''hijazensis'', is a reference to the al Hijaz region, in which it was discovered.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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