Rhinarium

The rhinarium (New Latin, "belonging to the nose"; plural: rhinaria)[1] is the furless skin surface surrounding the external openings of the nostrils in many mammals. Commonly it is referred to as the tip of the snout, and breeders of cats and dogs sometimes use the term nose leather. Informally, it may be called a "wet snout" or "wet nose", because its surface is moist in many species, e.g. healthy dogs and cats.[2]

In many species the rhinarium has a mid-line groove (cleft) - the philtrum - and the surface is wrinkled (crenellated).[3] Although the rhinarium is claimed to enhance the sense of smell[4], it is actually a touch-based sense organ that connects with a well-developed vomeronasal organ (VNO). Since pheromones are usually large, non-volatile molecules, the rhinarium is used to touch a scent-marked object and transfer the pheromone molecules down the philtrum to the VNO via the nasopalatine ducts that travel through the incisive foramen of the hard palate.[5]. It also acts as a wind direction detector: the cold receptors in the skin of the rhinarium respond to the location where evaporation is the highest, which is determined by the wind direction.

The study of the structure of the rhinarium and of its associated functions has proved to be of considerable importance in mammalian evolution and taxonomy.[6]

In an analogous connection of no relevance to vertebrate morphology, the term rhinarium sometimes is applied to chemosensory structures in invertebrates. For example, microscopic sensilla in the form of flattened sense organs on the antennae of aphids are referred to as rhinaria.[7]

Cat rhinarium
The rhinarium of a cat.
Canine-nose
A dog's rhinarium with philtrum
and conspicuous crenellations

Morphology

Morphologically the rhinarium is part of the olfactory system, but it is open to debate which part of the system from which it is derived. It might be part of the main olfactory system, which captures media-borne odors; or it might be part of the "second nose", the accessory olfactory system, which samples chemicals dissolved in fluids. An example of the former view is that the rhinarium is "an outward extension of the olfactory ... skin that covers the nasal passages, [which] contains nerve receptors for smell and touch."[2] If that interpretation is correct, and the rhinarium extends the olfactory epithelium that lines the nasal passages, then the rhinarium is part of the main system.[8]

In an opposing view, the philtrum ideally traces a path that continues over a notch in the upper lip, through a gap between the first incisors and premaxillae, along a "midline palatal groove" to "a canal that connects with the duct of the vomeronasal organ," part of the accessory system.[9] Where on the one hand the moisture (mucus) may have trapped odiferous molecules in the medium, on the other hand it may be the remnant of a fluid transmission system for molecules of pheromones.

Typically the rhinarium is crenellated (wrinkled or embossed), which, as a generalisation has been speculated to increase its sensory area, but there are many exceptions and variations among different mammalian taxa, and also variations in its innervation and sensilla, so it is appropriate to treat generalisations with caution in this matter.[6]

Function

Mammals with rhinaria tend to have more acute sense of smell, and the loss of the rhinarium in the haplorrhine primates is related to their decreased reliance on olfaction, being associated with other derived characteristics such as a reduced number of turbinates. The rhinarium is very useful to animals with good sense of smell because it acts as a wind direction detector. The cold receptors in the skin respond to the place where evaporation is the highest. Thus the detection of a particular smell is associated with the direction it came from.[10]

The rhinarium is adapted for different purposes in different mammals according to ecological niche. In aquatic mammals, development of lobes next to the nostrils allow them to be closed for diving. In mammals that dig or root with their noses, the rhinarium often develops into a resilient pad, with the nostrils off to the side or below, and capable of closing for exclusion of dust. Examples include the common wombat, marsupial mole, and members of the Chrysochloridae. In the elephants it has become a tactile organ. In the walrus, it is covered with stiff bristles to protect it during foraging for shellfish. In many animals the form and purpose of the rhinarium remains to be elucidated.

The evolutionary pressures also are not always clearly distinguishable and there have been upheavals in late 20th and early 21st century taxonomy. For example, the lack of an obvious rhinarium in Tarsiiformes has been suggested to be the consequence of the enormous development of the eyeballs, rather than a loss of relevance of olfaction.,[11] but the significance is currently debatable, because there currently is an influential body of opinion favouring inclusion of the tarsiers in the Haplorhini rather than in the Strepsirrhini as had been traditional.[12]

Taxonomy

Mammalian

The rhinarium is a general mammalian feature and therefore is likely to have been present in the stem mammals.

Primate

Primates are phylogenetically divided into Strepsirrhini, and the Haplorhini. The Strepsirrhini, which means "twisted-nosed", are primates with rhinaria, which is the ancestral condition. The Strepsirrhini consists of the prosimians: the lorises, and the lemurs. The Haplorhini, which means "simple-nosed", are primates which have replaced the rhinarium with a more mobile, continuous, dry upper lip. The Haplorhini consists of the Simians: the monkeys, the apes, and humans.

Prior to the 1970s, taxonomy ignored the fact that tarsiers have no rhinarium when placing them in the Strepsirrhini. However, since then the tarsiers have been placed in with the Haplorhini, and thus the absence of a rhinarium became diagnostic of the Haplorhini.[12]

Use of term in invertebrates

In an analogous connection of no relevance to vertebrate morphology, the term rhinarium sometimes is applied to chemosensory structures in invertebrates. For example, microscopic sensilla in the form of flattened sense organs on the antennae of aphids are referred to as rhinaria.[13]

See also

References

  1. ^ "rhinarium, -arium". Webster's Third New International Dictionary (Unabridged ed.). Encyclopædia Britannica, Inc. 1986.
  2. ^ a b Ankel-Simons, Friderun (2000). Primate anatomy: an introduction. San Diego: Academic Press. pp. 349–350. In most mammals we find a moist and shiny glandular area around the nostrils....
  3. ^ Lund University Faculty of Science Department of Biology Mammalian Rhinarium Group [1]
  4. ^ Rowe 1996, p. 13.
  5. ^ Ankel-Simons 2007, pp. 392–514.
  6. ^ a b Basbaum, Allan I. Kaneko, Akimichi, Shepherd, Gordon G. Westheimer, Gerald (editors). The Senses: A Comprehensive Reference. Academic press 2007. ISBN 978-0126394825
  7. ^ Du Yongjun Yan Fushun Tang Jue. Structure and Function of Olfactory Sensilla on the Antennae of Soybean Aphids, Aphis glycines. ACTA ENTOMOLOGICA SINICA 1995, Vol. 38 Issue (1): 1-7 [2]
  8. ^ Aspinall, Victoria; O'Reilly, Melanie (2004). Introduction to veterinary anatomy and physiology. Edinburgh; New York: Butterworth-Heinemann. p. 98. The chambers and the turbinates are covered by a ciliated mucous epithelium ... These nerve fibers reach the olfactory bulbs of the forebrain ....
  9. ^ Smith, Timothy; Rossie, James (2006), "Primate olfaction: anatomy and evolution", in Brewer, Warrick; Castle, David; Pantelis, Christos (eds.), Olfaction and the Brain, Cambridge; New York: Cambridge University Press, p. 139
  10. ^ S. Dijkgraaf; D. I. Zandee; Alberti Daniel François Addink, eds. (1978). Vergelijkende dierfysiologie (Comparative animal physiology) (in Dutch) (2nd ed.). Utrecht: Bohn, Scheltema & Holkema. ISBN 9789031303229.
  11. ^ Smith, T. D., & Bhatnagar, K. P. (2004). Microsmatic primates: reconsidering how and when size matters. The Anatomical Record Part B: The New Anatomist, 279(1), 24-31.
  12. ^ a b Frederick S. Szalay; Eric Delson (22 October 2013). Evolutionary History of the Primates. Elsevier Science. pp. 189–. ISBN 978-1-4832-8925-0.
  13. ^ Du Yongjun Yan Fushun Tang Jue. Structure and Function of Olfactory Sensilla on the Antennae of Soybean Aphids, Aphis glycines. ACTA ENTOMOLOGICA SINICA 1995, Vol. 38 Issue (1): 1-7 [3]

Bibliography

  • Fleagle, J. G. (1988). Primate adaptation and evolution. San Diego: Academic Press.

External links

African sheath-tailed bat

The African sheath-tailed bat (Coleura afra) is a species of sac-winged bat in the family Emballonuridae found in Angola, Benin, the Central African Republic, the Republic of the Congo, the Democratic Republic of the Congo, Ivory Coast, Djibouti, Eritrea, Ethiopia, Ghana, Guinea, Guinea-Bissau, Kenya, Madagascar, Mozambique, Nigeria, Somalia, Sudan, Tanzania, Togo, Uganda, and Yemen.

Its natural habitats are dry savanna, subarctic shrubland, subtropical or tropical dry shrubland, caves, and hot deserts. It is threatened by habitat loss, although still ranked as least concern.A young African sheath-tailed bat is called a pup, and a group is called a colony or a cloud.

Asiatic linsang

The Asiatic linsang (Prionodon) is a genus comprising two species native to Southeast Asia: the banded linsang (Prionodon linsang) and the spotted linsang (Prionodon pardicolor). Prionodon is considered a sister taxon of the Felidae.

Bengal fox

The Bengal fox (Vulpes bengalensis), also known as the Indian fox, is a fox endemic to the Indian subcontinent and is found from the Himalayan foothills and Terai of Nepal through southern India and from southern and eastern Pakistan to eastern India and southeastern Bangladesh.

Bengal slow loris

The Bengal slow loris (Nycticebus bengalensis) or northern slow loris is a strepsirrhine primate and a species of slow loris native to the Indian subcontinent and Indochina. Its geographic range is larger than that of any other slow loris species. Considered a subspecies of the Sunda slow loris (N. coucang) until 2001, phylogenetic analysis suggests that the Bengal slow loris is most closely related to the Sunda slow loris. However, some individuals in both species have mitochondrial DNA sequences that resemble those of the other species, due to introgressive hybridization. It is the largest species of slow loris, measuring 26 to 38 cm (10 to 15 in) from head to tail and weighing between 1 and 2.1 kg (2.2 and 4.6 lb). Like other slow lorises, it has a wet nose (rhinarium), a round head, flat face, large eyes, small ears, a vestigial tail, and dense, woolly fur. The toxin it secretes from its brachial gland (a scent gland in its arm) differs chemically from that of other slow loris species and may be used to communicate information about sex, age, health, and social status.

The Bengal slow loris is nocturnal and arboreal, occurring in both evergreen and deciduous forests. It prefers rainforests with dense canopies, and its presence in its native habitat indicates a healthy ecosystem. It is a seed disperser and pollinator, as well as a prey item for carnivores. Its diet primarily consists of fruit, but also includes insects, tree gum, snails, and small vertebrates. In winter, it relies on plant exudates, such as sap and tree gum. The species lives in small family groups, marks its territory with urine, and sleeps during the day by curling up in dense vegetation or in tree holes. It is a seasonal breeder, reproducing once every 12–18 months and usually giving birth to a single offspring. For the first three months, mothers carry their offspring, which reach sexual maturity at around 20 months. The Bengal slow loris can live up to 20 years.

The species is listed as "Vulnerable" on the IUCN Red List, and is threatened with extinction due to a growing demand in the exotic pet trade and traditional medicine. It is one of the most common animals sold in local animal markets. In traditional medicine, it is primarily used by wealthy to middle-class, urban women following childbirth, but also to treat stomach problems, broken bones, and sexually transmitted diseases. It is also hunted for food and suffers from habitat loss. Wild populations have declined severely, and it is locally extinct in several regions. It is found within many protected areas throughout its range, but this does not protect them from rampant poaching and illegal logging. Critical conservation issues for this species include enhancing protection measures, stricter enforcement of wildlife protection laws, and increased connectivity between fragmented protected areas.

Evolution of olfaction

Odor molecules are detected by the olfactory receptors (hereafter OR) in the olfactory epithelium of the nasal cavity. Each receptor type is expressed within a subset of neurons, from which they directly connect to the olfactory bulb in the brain. Olfaction is essential for survival in most vertebrates; however, the degree to which an animal depends on smell is highly varied. Great variation exists in the number of OR genes among vertebrate species, as shown through bioinformatic analyses. This diversity exists by virtue of the wide-ranging environments that they inhabit. For instance, dolphins that are secondarily adapted to an aquatic niche possess a considerably smaller subset of genes than most mammals. OR gene repertoires have also evolved in relation to other senses, as higher primates with well-developed vision systems tend to have a smaller number of OR genes. As such, investigating the evolutionary changes of OR genes can provide useful information on how genomes respond to environmental changes. Differences in smell sensitivity are also dependent on the anatomy of the olfactory apparatus, such as the size of the olfactory bulb and epithelium.

Nonetheless, the general features of the olfactory system are highly conserved among vertebrates, and, similarly to other sensory systems, olfaction has undergone fairly modest changes throughout the evolution of vertebrates. Phylogenetic analyses reveal that at least three distinct olfactory subsystems are broadly consistent in vertebrates, and a fourth accessory system (vomeronasal) solely arose in tetrapods.

Golden mole

Golden moles are small, insectivorous burrowing mammals endemic to Southern Africa, where their Afrikaans names are gouemolle or kruipmolle (singular gouemol or kruipmol). They comprise the family Chrysochloridae and as such they are taxonomically distinct from the true moles, family Talpidae, and other mole-like families, all of which, to various degrees, they resemble as a result of evolutionary convergence.

Haplorhini

Haplorhini (the haplorhines or the "dry-nosed" primates, the Greek name means "simple-nosed") is a suborder of primates containing the tarsiers and the simians (Simiiformes or anthropoids), as sister of the Strepsirrhini ("moist-nosed"). The name is sometimes spelled Haplorrhini. The simians include catarrhines (Old World monkeys and apes including humans), and the platyrrhines (New World monkeys).

The extinct omomyids, which are considered to be the most basal haplorhines, are believed to be more closely related to the tarsiers than to other haplorhines. The exact relationship is not yet fully established – Williams, Kay and Kirk (2010) prefer the view that tarsiers and simians share a common ancestor, and that common ancestor shares a common ancestor with the omomyids, citing evidence from analysis by Bajpal et al. in 2008; but they also note two other possibilities – that tarsiers are directly descended from omomyids, with simians being a separate line, or that both simians and tarsiers are descended from omomyids.Haplorhines share a number of derived features that distinguish them from the strepsirrhine "wet-nosed" primates (whose Greek name means "curved nose"), the other suborder of primates from which they diverged some 63 million years ago. The haplorhines, including tarsiers, have all lost the function of the terminal enzyme that manufactures Vitamin C, while the strepsirrhines, like most other orders of mammals, have retained this enzyme. Genetically, five short interspersed nuclear elements (SINEs) are common to all haplorhines whilst absent in strepsirrhines. The haplorhine upper lip, which has replaced the ancestral rhinarium found in strepsirrhines, is not directly connected to their nose or gum, allowing a large range of facial expressions. Their brain-to-body mass ratio is significantly greater than the strepsirrhines, and their primary sense is vision. Haplorhines have a postorbital plate, unlike the postorbital bar found in strepsirrhines. Most species are diurnal (the exceptions being the tarsiers and the night monkeys).

All anthropoids have a single-chambered uterus; tarsiers have a bicornate uterus like the strepsirrhines. Most species typically have single births, although twins and triplets are common for marmosets and tamarins. Despite similar gestation periods, haplorhine newborns are relatively much larger than strepsirrhine newborns, but have a longer dependence period on their mother. This difference in size and dependence is credited to the increased complexity of their behavior and natural history.

Lemur

Lemurs ( (listen) LEE-mər) (from Latin lemures – ghosts or spirits) are mammalian animals of the order primates, divided into 8 families and consisting of 15 genera and around 100 existing species. They are native only to the island of Madagascar. Most existing lemurs are small, have a pointed snout, large eyes, and a long tail. They chiefly live in trees (arboreal), and are active at night (nocturnal).

Lemurs share resemblance with other primates, but evolved independently from monkeys and apes. Due to Madagascar's highly seasonal climate, lemur evolution has produced a level of species diversity rivaling that of any other primate group. Until shortly after humans arrived on the island around 2,000 years ago, there were lemurs as large as a male gorilla. Most species have been discovered or promoted to full species status since the 1990s; however, lemur taxonomic classification is controversial and depends on which species concept is used.

Lemurs range in weight from the 30-gram (1.1 oz) mouse lemur to the 9-kilogram (20 lb) indri. Lemurs share many common basal primate traits, such as divergent digits on their hands and feet, and nails instead of claws (in most species). However, their brain-to-body size ratio is smaller than that of anthropoid primates. As with all strepsirrhine primates, they have a "wet nose" (rhinarium). Lemurs are generally the most social of the strepsirrhine primates, and communicate more with scents and vocalizations than with visual signals. Lemurs have a relatively low basal metabolic rate, and as a result may exhibit dormancy such as hibernation or torpor. They also have seasonal breeding and female social dominance. Most eat a wide variety of fruits and leaves, while some are specialists. Two species of lemurs may coexist the same forest due to different diets.

Lemur research during the 18th and 19th centuries focused on taxonomy and specimen collection. Modern studies of lemur ecology and behavior did not begin in earnest until the 1950s and 1960s. Initially hindered by political issues on Madagascar during the mid-1970s, field studies resumed in the 1980s. Lemurs are important for research because their mix of ancestral characteristics and traits shared with anthropoid primates can yield insights on primate and human evolution.

Many lemur species are threatened with extinction due to habitat loss and hunting. Although local traditions generally help protect lemurs and their forests, illegal logging, widespread poverty, and political instability hinder and undermine conservation efforts. Because of these threats and their declining numbers, the International Union for Conservation of Nature (IUCN) considers lemurs to be the world's most endangered mammals, noting that as of 2013 up to 90% of all lemur species face extinction within the next 20 to 25 years.

Nose

A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes through the pharynx, shared with the digestive system, and then into the rest of the respiratory system. In humans, the nose is located centrally on the face and serves as an alternative respiratory passage especially during suckling for infants. On most other mammals, it is located on the upper tip of the snout.

Omomyidae

Omomyidae is a family 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, and possibly Africa, making it one of two groups of Eocene primates with a geographic distribution spanning holarctic continents, the other being the adapids (family Adapidae). Early representatives of the Omomyidae and Adapidae appear suddenly at the beginning of the Eocene (59 mya) in North America, Europe, and Asia, and are the earliest known crown primates.

Pantherinae

Pantherinae is a subfamily within the family Felidae, which was named and first described by Reginald Innes Pocock in 1917.

The Pantherinae and the Felinae diverged from a common ancestor between 10.8 and 11.5 million years ago.

Paradoxurus

Paradoxurus is a genus within the viverrid family that was denominated and first described by Frédéric Cuvier in 1822. As of 2005, this genus was defined as comprising three species native to Southeast Asia:

the Asian palm civet (P. hermaphroditus)

the golden palm civet (P. zeylonensis)

the brown palm civet (P. jerdoni)In 2009, it was proposed to also include the golden wet-zone palm civet (P. aureus), the Sri Lankan brown palm civet (P. montanus) and the golden dry-zone palm civet (P. stenocephalus), which are endemic to Sri Lanka.

Philtrum

The philtrum (Latin: philtrum, Greek: φίλτρον philtron, lit. "love charm"), or medial cleft, is a vertical indentation in the middle area of the upper lip, common to many mammals, extending in humans from the nasal septum to the tubercle of the upper lip. Together with a glandular rhinarium and slit-like nostrils, it is believed to constitute the primitive condition for at least therian mammals. Monotremes lack a philtrum, though this could be due to the specialised, beak-like jaws in living species.

Primate

A primate ( (listen) PRY-mayt) (from Latin primat-, from primus: "prime, first rank") is a eutherian mammal constituting the taxonomic order Primates. Primates arose 85–55 million years ago from small terrestrial mammals (Primatomorpha), which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, altered shoulder girdle, and dexterous hands. 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 190–448 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the first decade of the 2000s, and eleven since 2010.

Primates are divided into two distinct suborders (see diagram under History of terminology). The first is the strepsirrhines (from Greek 'wet-nosed') – lemurs, galagos, and lorisids. (The colloquial names ending in -nosed actually refer to the rhinarium of the primate.) The second is haplorhines - the "dry-nosed" primates (from Greek 'simple-nosed') - tarsier, monkey, and ape clades, the last of these including humans. Simians (infraorder Simiiformes, from Greek simos 'flat-nosed') are monkeys and apes, cladistically including: the catarrhines (from Latin 'narrow nosed') consisting of the Old World monkeys and apes; and the platyrrhines (from Latin 'flat-nosed'): this division occurred about 60 million years ago. Forty million years ago, simians from Africa migrated to South America, presumably by drifting on debris, and gave rise to the New World monkeys. Twenty five million years ago the remaining Old World simians (catarrhines) split into apes and Old World monkeys. Common names for the simians are the (Old World) baboons, macaques, gibbons, and great apes; and the (New World) capuchins, howlers and squirrel monkeys.

Primates have large brains (relative to body size) compared to other mammals, as well as an increased reliance on visual acuity at the expense of the sense of smell, which is the dominant sensory system in most mammals. These features are more developed in monkeys and apes, and noticeably less so in lorises and lemurs. Some primates are trichromats, with three independent channels for conveying color information. Except for apes, primates have tails. Most primates also have opposable thumbs. Many species are sexually dimorphic; differences may include muscle mass, fat distribution, pelvic width, canine tooth size, hair distribution, and coloration. Primates have slower rates of development than other similarly sized mammals, reach maturity later, and have longer lifespans. Depending on the species, adults may live in solitude, in mated pairs, or in groups of up to hundreds of members. Some primates, including gorillas, humans and baboons, are primarily terrestrial rather than arboreal, but all species have adaptations for climbing trees. Arboreal locomotion techniques used include leaping from tree to tree and swinging between branches of trees (brachiation); terrestrial locomotion techniques include walking on two limbs (bipedalism) and modified walking on four limbs (knuckle-walking).

Primates are among the most social of animals, forming pairs or family groups, uni-male harems, and multi-male/multi-female groups. Non-human primates have at four types of social systems, many defined by the amount of movement by adolescent females between groups. Most primate species remain at least partly arboreal: the exceptions are some great apes, baboons, and humans, who left the trees for the ground and now inhabit every continent.

Close interactions between humans and non-human primates (NHPs) can create opportunities for the transmission of zoonotic diseases, especially virus diseases, including herpes, measles, ebola, rabies, and hepatitis. Thousands of non-human primates are used in research around the world because of their psychological and physiological similarity to humans. About 60% of primate species are threatened with extinction. Common threats include deforestation, forest fragmentation, monkey drives, and primate hunting for use in medicines, as pets, and for food. Large-scale tropical forest clearing for agriculture most threatens primates.

Snout

A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the equivalent structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of some animals is called the rhinarium (colloquially this is the "cold wet nose" of some animals). The rhinarium is often associated with a stronger sense of olfaction. The snout is considered a weak point on most animals: because of its structure, an animal can be easily stunned or knocked out, or even have its snout snapped by applying sufficient force.

Strepsirrhini

Strepsirrhini or Strepsirhini ( (listen); STREP-sə-RY-nee) 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 that 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.

Strepsirrhines are defined by their "wet" (moist) rhinarium (the tip of the snout) - hence the colloquial but inaccurate term "wet-nosed" - similar to the rhineria of dogs and cats. They also have a smaller brain than comparably sized simians, large olfactory lobes for smell, a vomeronasal organ to detect pheromones, and a bicornuate uterus with an epitheliochorial placenta. Their eyes contain a reflective layer to improve their night vision, and their eye sockets include a ring of bone around the eye, but they lack a wall of thin bone behind it. Strepsirrhine primates produce their own vitamin C, whereas haplorhine primates must obtain it from their diets. Lemuriform primates are characterized by a toothcomb, a specialized set of teeth in the front, lower part of the mouth mostly used for combing fur during grooming.

Many of today's living strepsirrhines are endangered due to habitat destruction, hunting for bushmeat, and live capture for the exotic pet trade. Both living and extinct strepsirrhines are behaviorally diverse, although all are primarily arboreal (tree-dwelling). Most living lemuriforms are nocturnal, while most adapiforms were diurnal. Both living and extinct groups primarily fed on fruit, leaves, and insects.

Sunda slow loris

The Sunda slow loris (Nycticebus coucang) or greater slow loris is a strepsirrhine primate and a species of slow loris native to Indonesia, western Malaysia, southern Thailand and Singapore. It measures 27 to 38 cm (11 to 15 in) from head to tail and weighs between 599 and 685 g (21.1 and 24.2 oz). Like other slow lorises, it has a wet nose (rhinarium), a round head, small ears hidden in thick fur, a flat face, large eyes and a vestigial tail.

The Sunda slow loris is nocturnal and arboreal, typically occurring in evergreen forests. It prefers rainforests with continuous dense canopies and has an extremely low metabolic rate compared to other mammals of its size. Its diet consists of sap, floral nectar, fruit and arthropods. It will feed on exudates such as gum and sap by licking wounds in trees. The species is generally solitary; one study showed only 8% of its active time was spent near other individuals. Social behavior makes up a very small part of the activity budget, though it has monogamous mating system with the offspring living with the parents. It sleeps during the day, rolled up in a ball in hidden parts of trees above the ground, often on branches, twigs, palm fronds, or lianas. The species is polyoestrous, usually giving birth to a single offspring after a gestation period of 192 days. The young disperses between 16 and 27 months, generally when it is sexually mature.

The species is listed as "Vulnerable" on the IUCN Red List. It is threatened with extinction due to a growing demand in the exotic pet trade, and has become one of the most abundant primate species on sale at Indonesian pet markets. Its teeth are often pulled out before being sold as pets which can result in infection and/or death, this process makes reintroduction to the wild impossible. It also suffers from habitat loss, which has been severe in the areas in which it is found.

Wallaroo

Wallaroo is any of three closely related species of moderately large macropod, intermediate in size between the kangaroos and the wallabies. The word "wallaroo" is from Dharug walaru. In general, a large, slim-bodied macropod of the open plains is called a "kangaroo"; a small to medium-sized one, particularly if it is relatively thick-set, is a "wallaby": most wallaroos are only a little smaller than a kangaroo, fairly thickset, and are found in open country. All share a particular habit of stance: wrists raised, elbows tucked close into the body, and shoulders thrown back, and all have a large, black-skinned rhinarium.

The common wallaroo (Macropus robustus or wallaroo) is the best-known species. There are four subspecies of the common wallaroo: the eastern wallaroo and the euro, which are both widespread, and two of more restricted range, one from Barrow Island, the other from the Kimberley.

The black wallaroo (Macropus bernardus) occupies an area of steep, rocky ground in Arnhem Land. At around 60 to 70 cm (24 to 28 inches) in length (excluding tail) it is the smallest wallaroo and the most heavily built. Males weigh 19 to 22 kg (42 to 49 lb), females about 13 kg (29 lb). Because it is very wary and is found only in a small area of remote and very rugged country, it is little known.

Macropus antilopinus is the exception among wallaroos. It is, essentially, the far-northern equivalent of the eastern and western grey kangaroos. Like them, it is a creature of the grassy plains and woodlands, and gregarious, where the other wallaroos are solitary. Because of this difference, it is sometimes called the antilopine kangaroo.

Woolly giant rat

The woolly giant rat (Kunsia tomentosus) is a species of large burrowing rodent native to South America. No subspecies are currently recognised.

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