Saadanius

Skull Fragment of Saadanius hijazensis

• Region Hejaz, Saudi Arabia

Saadanius hijazensis is an extinct species of primates that occurred during the middle Oligocene in the Arabian Peninsula. In Saudi Arabia, discovered fossils to put this kind, dated their discoverer in the original description of Saadanius hijazensis in 2010 on the basis of radiometric methods at least 26-21 million years, and based on biostratigraphic analyzes - including animals from the group of Anthracotheriidae - in the period prior to about 29-28 million years ago. The fossils were by their discoverers in the vicinity of the last common ancestor of Cercopithecidae ( Cercopithecoidea ) and anthropoids ( Hominoidea ) provided. Your Fund was also rated as a confirmation of the hypothesis that the early evolution of Old World monkeys took place in the African- Arab region.

Naming

This name is derived from Arabic Saadanius sa'adan / سعدان / sa ʿ dān /, monkey '. The epithet refers to the hijazensis locality in the region of Hejaz ( Al- Hijaz الحجاز, DMG al - Ḥiǧāz ), in the English language Al Hijaz.

The type specimen

As holotype fragment of the facial skeleton of a presumably adult male individual was reported in the original description (archive number SGS -UM 2009-002 ), which is kept in the paläoontologischen department of the Saudi Geological Survey in Jeddah. Could be assigned to this fossil, inter alia, fragments of bone from the area of ​​the eye sockets and the nose, the palate almost completely preserved as well as parts of the upper jaw with few remaining molars, incisors and a canine.

The fossil bones were bared up in 2009 on the northwest edge of Harrat Al Ujayfa in the Hejaz region, Saudi Arabia, above a oolitic iron formation while searching for fossil whale and dinosaur bones. Their discoverer, Iyad S. Zalmout was, at that time a postdoctoral fellow in the laboratory of Philip D. Gingerich, University of Michigan.

Saadanius hijazensis is also the type species of the genus Saadanius.

In the first description of this genus and species of 2010, also has recently introduced family Saadaniidae and the newly introduced superfamily Saadanioidea within the Old World monkeys ( catarrhines ) have been assigned.

Significance of the find

Finds of fossil Old World monkeys from the Oligocene - the period before about 34 to 21 million years - are so far relatively rare. However, they are considered particularly important for the reconstruction of the evolutionary history of human -like, as their lineage separated in this era from that of the Cercopithecidae. Among the primate fossils of this era include, for example, the types of dated one aged 35 to 30 million annual family Propliothecoidea, the genus Aegyptopithecus ( 34-28 million years) and the much younger, live in front of 23 bis 16 million years genus Kamoyapithecus. With an age of about 29 and 28 million years Saadanius hijazensis thus fills a gap in the sequence of traditional fossil of the middle Oligocene.

According to reconstruction in the original description Saadanius united hijazensis certain original features and newly acquired characteristics, it was concluded that the separation of the anthropoids of the Cercopithecidae - as already had suggesting other fossil finds - in the period between 29-28 and 24 million years ago today carried out; the lower limit of 24 million years was derived from the classification of Kamoyapithecus in the anthropoids. With the help of so-called molecular clock - whose calibration is controversial - was, however, calculated that the separation between 34,5 und 29.2 million years was made.

Description of the findings

Saadanius hijazensis was alive probably the size of a Siamang and weighed about 15 to 20 kilograms. It lacks all the special features that make it possible to distinguish monkeys relatives and human -like each other. The shape of his face is according to the first description intermediate between Aegyptopithecus and the later species of the Miocene; it probably resembled more like the face of today baboons as the face of the gibbons. The salient features of the fossil are especially be relatively elongated face and snout -like protrusion of the facial bones; further than the " original " feature rated lack of a frontal sinus, the presence of very small canines and the construction of relatively wide, covered with only a thin enamel Great molars. As flashy " newly acquired " characteristic is, however, the - derivable from the resulting temporal bone - construction of the external auditory canal.

Visible are also a deep bite mark in the middle area of the face as well as a potentially leading to death injection site on the right.

This habitat of Saadanius hijazensis According to those found in the same strata crop residues include mangrove forests.