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 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 found in living catarrhines. However, it had a bony 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.
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 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.[1] The specimen was discovered in February 2009[2] 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, Zalmout found the jawbone of an anthracotheriid, which dated to the 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.[3] The fossil was soon recovered by a joint expedition involving the SGS and the University of Michigan.[1]
The fossil was not formally described until 2010 when its discovery was announced in the journal Nature.[2] The fossil was dated to about 28 or 29 million years ago based on comparisons of fossils of anthracotheriids and paenungulates found nearby with fossils from similarly aged African deposits.[1][4] However, the date has yet to be confirmed by other dating techniques.[4] The genus name, Saadanius, comes from the Arabic word, saadan (Arabic: 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.[1]
Saadanius had a longer face than living catarrhines,[4] more closely resembling New World monkeys in appearance, although it was larger—possibly the size of a gibbon.[5] Its enlarged, deep-rooted canine teeth, the diastema between its canine teeth and second incisors, and its sagittal crest suggest that the specimen was a male.[1] These features are shared among male Old World monkeys.[2] Saadanius lacks the advanced frontal sinus found in living catarrhines,[1][2][4] but it does possess an ectotympanic, found in living catarrhines. Propliopithecoids, the oldest stem group of catarrhines, which date back 35 to 30 mya, lacked a fully developed ectotympanic.[1][4]
The specimen had serious puncture wounds on the front of the skull, indicating that it had been preyed upon by a large carnivore.[2] One puncture wound was on the right side of the braincase and may have been the fatal blow. There was also a bite mark on the frontal trigone.[1]