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Primates is an order of mammals, which is further divided into the strepsirrhines, which include lemurs, galagos, and lorisids; and the haplorhines, which include tarsiers and simians. Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted for life in tropical forests: many primate characteristics represent adaptations to the challenging environment among tree tops, including large brain sizes, binocular vision, color vision, vocalizations, shoulder girdles allowing a large degree of movement in the upper limbs, and opposable thumbs that enable better grasping and dexterity. Primates range in size from Madame Berthe's mouse lemur, which weighs 30 g (1 oz), to the eastern gorilla, weighing over 200 kg (440 lb). There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and six in the 2020s.
Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of their erosive and expansile properties. This can result in the destruction of the bones of the middle ear (ossicles), as well as growth through the base of the skull into the brain. They often become infected and can result in chronically draining ears. Treatment almost always consists of surgical removal.
In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear, and thence to the oval window in the fluid-filled cochlea. The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid. The malleus bone bridges the gap between the eardrum and the other ossicles.
The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the organ of Corti, the sensory organ of hearing, which is distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea.
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales, and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555.
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
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.
Strepsirrhini or Strepsirhini is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Collectively they are referred to as strepsirrhines. Also belonging to the suborder are the extinct adapiform primates which thrived during the Eocene in Europe, North America, and Asia, but disappeared from most of the Northern Hemisphere as the climate cooled. Adapiforms are sometimes referred to as being "lemur-like", although the diversity of both lemurs and adapiforms does not support this comparison.
Omomyidae is a group of early primates that radiated during the Eocene epoch between about 55 to 34 million years ago (mya). Fossil omomyids are found in North America, Europe & Asia, making it one of two groups of Eocene primates with a geographic distribution spanning holarctic continents, the other being the adapids. Early representatives of the Omomyidae and Adapidae appear suddenly at the beginning of the Eocene in North America, Europe, and Asia, and are the earliest known crown primates.
The baculum, also known as the penis bone, penile bone, os penis, os genitale, or os priapi, is a bone in the penis of many placental mammals. It is absent from the human penis, but present in the penises of some primates, such as the gorilla and the chimpanzee. The baculum arises from primordial cells in soft tissues of the penis, and its formation is largely influenced by androgens. The bone lies above the urethra, and it aids sexual reproduction by maintaining stiffness during sexual penetration. The homologue to the baculum in female mammals is the baubellum, a bone in the clitoris.
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.
Knuckle-walking is a form of quadrupedal walking in which the forelimbs hold the fingers in a partially flexed posture that allows body weight to press down on the ground through the knuckles. Gorillas and chimpanzees use this style of locomotion, as do anteaters and platypuses.
The brow ridge, or supraorbital ridge known as superciliary arch in medicine, is a bony ridge located above the eye sockets of all primates and some other animals. In humans, the eyebrows are located on their lower margin.
The caroticotympanic artery is a small, sometimes doubled artery which arises from the internal carotid artery. It leaves the carotid canal through a foramen to reach the tympanic cavity. It contributes arterial supply to the osseous part of the pharyngotympanic tube.
The evolution of mammalian auditory ossicles was an evolutionary process that resulted in the formation of the bones of the mammalian middle ear. These bones, or ossicles, are a defining characteristic of all mammals. The event is well-documented and important as a demonstration of transitional forms and exaptation, the re-purposing of existing structures during evolution.
In the auditory system, the columella contributes to hearing in amphibians, reptiles and birds. The columella form thin, bony structures in the interior of the skull and serve the purpose of transmitting sounds from the eardrum. It is an evolutionary homolog of the stapes, one of the auditory ossicles in mammals.
Cochlea is Latin for “snail, shell or screw” and originates from the Greek word κοχλίας kokhlias. The modern definition, the auditory portion of the inner ear, originated in the late 17th century. Within the mammalian cochlea exists the organ of Corti, which contains hair cells that are responsible for translating the vibrations it receives from surrounding fluid-filled ducts into electrical impulses that are sent to the brain to process sound.
Pliopithecoidea is an extinct superfamily of catarrhine primates that inhabited Asia and Europe during the Miocene. Although they were once a widespread and diverse group of primates, the pliopithecoids have no living descendants.
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.
The entotympanic is a bone found in the ear region of many placental mammals. When present it forms the medioventral part of the auditory bulla; it is a neomorphic element derived from the tubal cartilage and the sheath of the tympanohyal. It is found in a wide variety of placental mammals, including Xenarthra, Afroinsectophilia, Hyracoidea, Pholidota, Carnivora, Perissodactyla, Chiroptera, Dermoptera, and Scandentia; it is reduced or absent in Glires, Primates, Eulipotyphla, and Artiodactyla. It is the only common neomorphic element of the mammalian skull.
References
- ↑ Fricano, Ellen Elise Irwin (2018). "The Primate Ectotympanic Tube: Correlates of Structure, Function, and Development".
{{cite journal}}: Cite journal requires|journal=(help) - ↑ Ankel-Simons, F. (2007). Primate Anatomy (3rd ed.). Academic Press. pp. 435–436. ISBN 0-12-372576-3.
- ↑ Archibald, J.D. (1977). "Ectotympanic bone and internal carotid circulation of eutherians in reference to anthropoid origins". Journal of Human Evolution. 6 (7): 609–622. doi:10.1016/S0047-2484(77)80134-6.
- ↑ Sellers, W.I. "Strepsirhine/Haplorhine Split" (PDF). Retrieved 18 August 2010.[ permanent dead link ]
- ↑ Maier, Wolfgang (August 2013). "The entotympanic in late fetal artiodactyla (Mammalia)". Journal of Morphology. 274 (8): 926–939. doi:10.1002/jmor.20149. ISSN 0362-2525.
