Saadanius

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Saadanius
Temporal range: 29–28  Ma
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Saadanius hijazensis 002.jpg
Saadanius hijazensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Parvorder: Catarrhini
Superfamily: Saadanioidea
Zalmout et al., 2010
Family: Saadaniidae
Zalmout et al., 2010
Genus: Saadanius
Zalmout et al., 2010
Species:
S. hijazensis
Binomial name
Saadanius hijazensis
Zalmout et al., 2010

Saadanius is a genus of fossil primates 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 comparison with both living and fossil catarrhines.

Contents

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. Its discovery provided new information about the early evolution of catarrhines.

Taxonomy

The specimen was found with the palate and teeth facing upward. Saadanius hijazensis 003.jpg
The specimen was found with the palate and teeth facing upward.

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). [1] The specimen was discovered in southwestern Saudi Arabia 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 formally described in 2010 when its discovery was announced in the journal Nature . [2] 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]

Description

Front and side view of Saadanius hijazensis. Saadanius hijazensis 001.jpg
Front and side view of Saadanius hijazensis.

The only known fossil of Saadanius is a partial skull, preserving much of the face and palate and many of the teeth. Two bite marks, one of which may have been fatal, are visible on the skull. [1] 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 had a longer face than living catarrhines, [4] more closely resembling New World monkeys in appearance, [5] although it was larger, similar in size to the siamang. [1] It most closely resembles the older fossil Aegyptopithecus , but it also shares some similarities with later catarrhines. [1] For example, it lacks the advanced frontal sinus found in living hominoids, [1] [2] [4] but it does possess a tube-shaped 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 upper molars were relatively wide, with prominent well-separated cusps. The third upper molar (M3) was larger than the second (M2). The canines were relatively smaller than in some later taxa like Proconsul , with an approximately oval cross-section. The nasal aperture is relatively large, though unlike in Dendropithecus it does not extend between the roots of the first incisors. The nasals are long and narrow and do not touch the premaxillae. [1]

Phylogeny

Saadanius placement within the catarrhine clade [1]
  Catarrhini  

  Propliopithecoidea  ( Aegyptopithecus ) 

  Pliopithecoidea  ( Pliopithecus ) 

 Saadanius 

crown catarrhines
(living and fossil)

Comparative anatomy and cladistic analysis performed when the fossil was discovered indicate that Saadanius is more closely related to the last common ancestor of crown catarrhines than any other known fossil catarrhines, placing the common ancestry of Catarrhini in Arabia and Africa. Other stem catarrhines include propliopithecoids, such as Aegyptopithecus , and pliopithecoids, such as Pliopithecus . The closer similarities between Saadanius and crown catarrhines, particularly its ectotympanic, suggest Saadanius of all known fossil primates most closely resembled the last common ancestor of living catarrhines. [1] Some later studies instead found Saadanius to be more closely related to Old World monkeys than to hominoids, placing it among crown catarrhines. [6] [7]

Animated 3D view of the skull

The discovery of Saadanius provides new evidence for competing hypotheses about the facial appearance of the ancestral crown catarrhines, or common ancestor. One reconstruction is based on living catarrhine traits and predicts a short face and a rounded braincase, similar to that of a gibbon. Another reconstruction, based on the morphology of early Miocene apes and the basal cercopithecoid Victoriapithecus , predicts that the last common ancestor had a projecting snout and tall face, like that of living baboons and the oldest fossil apes and Old World monkeys. The conservative features of Saadanius, similar to those of the older stem catarrhines, support the latter hypothesis, according to Zalmout et al. [1] [4] [3] However, one palaeontologist, Eric Delson, has cautioned that geological pressure may have distorted the shape of the skull. [4]

According to Zalmout et al., Saadanius may also help resolve the age of the hominoid–cercopithecoid split. [1] [4] Paleoanthropological work has typically placed the divergence between 25 and 23 mya, but genetic-based estimates have placed it in the early Oligocene, approximately 33 mya. Despite the predictions from the genetic tests, little fossil evidence has been found for a last common ancestor between 30 and 23 mya, favoring a later split. Only isolated teeth of Kamoyapithecus hinted at the existence of potential basal hominoids in the late Oligocene (between 24 and 27.5 mya), [1] [5] while the oldest fossil Old World monkey, Victoriapithecus macinnesi, dates to 19 mya. [8] With the discovery of Saadanius, Zalmout et al. suggested a later split than the genetic data, dating between 29–28 and 24 mya. [1] [5] However, Pozzi et al. later argued that although Saadanius is a significant discovery, because it is a stem catarrhine, it could not be used to date the divergence of the crown group. The presence of stem taxa in the fossil record does not indicate that crown groups have evolved, and stem taxa may survive for millions of years after the crown taxa appear. For this reason, the fossil record can only suggest a hard minimum boundary for divergence dates, which corresponds to the first appearance of a crown taxon. Furthermore, Pozzi et al. pointed out that the supplementary material published by Zalmout et al. demonstrated that Pliopithecoidea were more closely related to living catarrhines than Saadanius. [8] In 2013, two other Oligocene catarrhines were announced, the proposed Old World monkey Nsungwepithecus and the hominoid Rukwapithecus . [9]

The fossil find has also been seen by the SGS as an important find for Saudi Arabia, because it enriches the fossil record for the region. As a result of the find, both the SGS and the University of Michigan are considering more collaborative field explorations in the country. [3]

Paleoecology

Saadanius was found 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. Other fossils recovered from the same horizon include a few teeth and jaws of the following mammals: [1]

The presence of a gomphothere and mammutid suggests that the deposits are younger than the Jebel Qatrani Formation at Fayum in Egypt, while the other taxa indicate an older age than the Chilga Formation of Ethiopia. This led Zalmout's team to assign an age of 28 or 29 million years to the Shumaysi Formation fauna. [1] [4] However, the date has yet to be confirmed by other dating techniques. [4] A 2020 review assigned the Harrat Al Ujayfa locality to the Turkwelian African land mammal age, which started 28.2 million years ago. [10]

Like other catarrhine primates, Saadanius was probably a tree-dweller. [5] During the time it would have lived, the Red Sea had not yet formed, and new plant and animal species would have been arriving from nearby Eurasia as it converged with the Afro-Arabian landmass. [2]

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]

Related Research Articles

<span class="mw-page-title-main">Ape</span> Branch of primates

Apes are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia, which together with its sister group Cercopithecidae form the catarrhine clade, cladistically making them monkeys. Apes do not have tails due to a mutation of the TBXT gene. In traditional and non-scientific use, the term ape can include tailless primates taxonomically considered Cercopithecidae, and is thus not equivalent to the scientific taxon Hominoidea. There are two extant branches of the superfamily Hominoidea: the gibbons, or lesser apes; and the hominids, or great apes.

<span class="mw-page-title-main">Old World monkey</span> Family of mammals

Old World monkeys are primates in the family Cercopithecidae. Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons, red colobus and macaques. Common names for other Old World monkeys include the talapoin, guenon, colobus, douc, vervet, gelada, mangabey, langur, mandrill, surili (Presbytis), patas, and proboscis monkey.

<span class="mw-page-title-main">Catarrhini</span> Group of Old World monkeys and apes

The parvorder Catarrhini consists of the Cercopithecoidea and apes (Hominoidea). In 1812, Geoffroy grouped those two groups together and established the name Catarrhini, "Old World monkeys",. Its sister in the infraorder Simiiformes is the parvorder Platyrrhini. There has been some resistance to directly designate apes as monkeys despite the scientific evidence, so "Old World monkey" may be taken to mean the Cercopithecoidea or the Catarrhini. That apes are monkeys was already realized by Georges-Louis Leclerc, Comte de Buffon in the 18th century. Linnaeus placed this group in 1758 together with what we now recognise as the tarsiers and the New World monkeys, in a single genus "Simia". The Catarrhini are all native to Africa and Asia. Members of this parvorder are called catarrhines.

<span class="mw-page-title-main">Haplorhini</span> Suborder of primates

Haplorhini, the haplorhines or the "dry-nosed" primates is a suborder of primates containing the tarsiers and the simians, as sister of the Strepsirrhini ("moist-nosed"). The name is sometimes spelled Haplorrhini. The simians include catarrhines, and the platyrrhines.

<span class="mw-page-title-main">Lemuriformes</span> Infraorder of primates

Lemuriformes is the sole extant infraorder of primate that falls under the suborder Strepsirrhini. It includes the lemurs of Madagascar, as well as the galagos and lorisids of Africa and Asia, although a popular alternative taxonomy places the lorisoids in their own infraorder, Lorisiformes.

<span class="mw-page-title-main">Simian</span> Infraorder of primates

The simians, anthropoids, or higher primates are an infraorder of primates containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders Platyrrhini and Catarrhini, the latter of which consists of the family Cercopithecidae and the superfamily Hominoidea.

<i>Aegyptopithecus</i> Extinct single-species genus of primate

Aegyptopithecus is an early fossil catarrhine that predates the divergence between hominoids (apes) and cercopithecids. It is known from a single species, Aegyptopithecus zeuxis, which lived around 38-29.5 million years ago in the early part of the Oligocene epoch. It likely resembled modern-day New World monkeys, and was about the same size as a modern howler monkey, which is about 56 to 92 cm long. Aegyptopithecus fossils have been found in the Jebel Qatrani Formation of modern-day Egypt. Aegyptopithecus is believed to be a stem-catarrhine, a crucial link between Eocene and Miocene fossils.

<span class="mw-page-title-main">Hominini</span> Tribe of mammals

The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera Homo (humans) and Pan and in standard usage excludes the genus Gorilla (gorillas).

<span class="mw-page-title-main">Monkey</span> Animal of the "higher primates" (the simians), but excluding the apes

Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, thus monkeys constitute an incomplete paraphyletic grouping; however, in the broader sense based on cladistics, apes (Hominoidea) are also included, making the terms monkeys and simians synonyms in regard to their scope.

<span class="mw-page-title-main">Rusinga Island</span> Island in Kenya

Rusinga Island, with an elongated shape approximately 10 miles (16 km) from end to end and 3 miles (5 km) at its widest point, lies in the eastern part of Lake Victoria at the mouth of the Winam Gulf. Part of Kenya, it is linked to Mbita Point on the mainland by the new Rusinga-Mbita bridge which replaced the old causeway.

<i>Lufengpithecus</i> Extinct genus of primates

Lufengpithecus is an extinct genus of ape, known from the Late Miocene of East Asia. It is known from thousands of dental remains and a few skulls and probably weighed about 50 kg (110 lb). It contains three species: L. lufengensis, L. hudienensis and L. keiyuanensis. Lufengpithecus lufengensis is from the Late Miocene found in China, named after the Lufeng site and dated around 6.2 Ma. Lufengpithecus is either thought to be the sister group to Ponginae, or the sister to the clade containing Ponginae and Homininae.

<span class="mw-page-title-main">Toothcomb</span> Dental structure found in some mammals

A toothcomb is a dental structure found in some mammals, comprising a group of front teeth arranged in a manner that facilitates grooming, similar to a hair comb. The toothcomb occurs in lemuriform primates, treeshrews, colugos, hyraxes, and some African antelopes. The structures evolved independently in different types of mammals through convergent evolution and varies both in dental composition and structure. In most mammals the comb is formed by a group of teeth with fine spaces between them. The toothcombs in most mammals include incisors only, while in lemuriform primates they include incisors and canine teeth that tilt forward at the front of the lower jaw, followed by a canine-shaped first premolar. The toothcombs of colugos and hyraxes take a different form with the individual incisors being serrated, providing multiple tines per tooth.

Kamoyapithecus was a primate that lived in Africa during the late Oligocene period, about 24.2-27.5 million years ago. First found in 1948 as part of a University of California, Berkeley expedition, it was at first thought to be under a form of Proconsul by C.T. Madden in 1980, but after a re-examination by Meave Leakey and associates later, the fossils were moved under a new genus Kamoyapithecus, named after the renowned fossil finder Kamoya Kimeu. The genus is represented by only one species, K. hamiltoni.

<span class="mw-page-title-main">Evolution of lemurs</span> History of primate evolution on Madagascar

Lemurs, primates belonging to the suborder Strepsirrhini which branched off from other primates less than 63 million years ago, evolved on the island of Madagascar, for at least 40 million years. They share some traits with the most basal primates, and thus are often confused as being ancestral to modern monkeys, apes, and humans. Instead, they merely resemble ancestral primates.

Parapithecidae is an extinct family of primates which lived in the Eocene and Oligocene periods in Egypt. Eocene fossils from Myanmar are sometimes included in the family in addition. They showed certain similarities in dentition to Condylarthra, but had short faces and jaws shaped like those of tarsiers. They are part of the superfamily Parapithecoidea, perhaps equally related to Ceboidea and Cercopithecoidea plus Hominoidea - but the placement of Parapithecoidea is substantially uncertain.

<i>Nacholapithecus</i> Extinct genus of hominoids

Nacholapithecus kerioi was an ape that lived 14-15 million years ago during the Middle Miocene. Fossils have been found in the Nachola formation in northern Kenya. The only member of the genus Nacholapithecus, it is thought to be a key genus in early hominid evolution. Similar in body plan to Proconsul, it had a long vertebral column with six lumbar vertebrae, no tail, a narrow torso, large upper limbs with mobile shoulder joints, and long feet.

<i>Anapithecus</i> Extinct genus of primates

Anapithecus is a late Miocene primate known from fossil locations in Hungary and Austria. Many Anapithecus fossils come from the site of Rudabánya, in northern Hungary, where Anapithecus lived alongside the ape Rudapithecus. The only species in the genus, Anapithecus hernyaki, is named after Gabor Hernyák, chief geologist of the Iron Ore Works of Rudabánya.

<span class="mw-page-title-main">Evolution of primates</span> Origin and diversification of primates through geologic time

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<span class="mw-page-title-main">Pliopithecoidea</span> Extinct superfamily of primates

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<i>Epipliopithecus</i> Extinct genus of primates

Epipliopithecus vindobonensis is an extinct species of pliopithecoid primate recovered from the Middle Miocene deposits of Devínska Nová Ves fissure in western Slovakia. Epipliopithecus is one of the few pliopithecoids for which both cranial and post-cranial fossil material has been recovered. Most pliopithecoids are known only from fossilized teeth, whereas Epipliopithecus is known from three nearly complete skeletons. As such, Epipliopithecus has greatly informed the modern understanding of pliopithecoid anatomy, locomotion, and phylogeny.

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