85-655: Several; see text Opossums ( / ə ˈ p ɒ s ə m z / ) are members of the marsupial order Didelphimorphia ( / d aɪ ˌ d ɛ l f ɪ ˈ m ɔːr f i ə / ) endemic to the Americas . The largest order of marsupials in the Western Hemisphere , it comprises 126 species in 18 genera . Opossums originated in South America and entered North America in the Great American Interchange following
170-574: A barrel with fresh or rotten fruit to attract opossums that would feed on the fruit or insects. In northern/central Mexico, opossums are known as tlacuache or tlacuatzin . Their tails are eaten as a folk remedy to improve fertility. In the Yucatán peninsula they are known in the Yucatec Mayan language as "och" and they are not considered part of the regular diet by Mayan people, but still considered edible in times of famine. Opossum oil (possum grease)
255-497: A clade stemming from the last common ancestor of extant metatherians , which encompasses all mammals more closely related to marsupials than to placentals . This evolutionary split between placentals and marsupials occurred at least 125 million years ago, possibly dating back over 160 million years to the Middle Jurassic - Early Cretaceous period. Presently, close to 70% of the 334 extant species of marsupials are concentrated on
340-484: A defense mechanism, allowing a rare reversal of an evolutionary arms race where the former prey has become the predator, whereas others have suggested it arose as a predatory adaptation given that it also occurs in other predatory mammals and does not occur in opossums that do not regularly eat other vertebrates. The fer-de-lance , one of the most venomous snakes in the New World , may have developed its highly potent venom as
425-632: A different order. The opossum is typically a nonaggressive animal and almost never carries the virus that causes rabies . The word opossum is derived from the Powhatan language and was first recorded between 1607 and 1611 by John Smith (as opassom ) and William Strachey (as aposoum ). Possum was first recorded in 1613. Both men encountered the language at the English settlement of Jamestown, Virginia , which Smith helped to found and where Strachey later served as its first secretary. Strachey's notes describe
510-775: A distinct family (Prothylacynidae), phylogenetic analyses have found that these animals do not represent a monophyletic group. The exact age of most Eocene species of sparassodonts is uncertain, given the lack of precise stratigraphic information associated with most specimens and the recent division of the Casamayoran SALMA into the Vacan and Barrancan SALMAs. Several other metatherian taxa have been suggested to be sparassodonts or closely related to sparassodonts. The australian Murgon taxa Archaeonothos has been noted as being similar to sparassodonts, but currently its relationships are not fully concluded. Carneiro (2018) recovered
595-612: A diverse group of mammals belonging to the infraclass Marsupialia . They are natively found in Australasia , Wallacea , and the Americas . One of the defining features of marsupials is their unique reproductive strategy, where the young are born in a relatively undeveloped state and then nurtured within a pouch on their mother's abdomen. Living marsupials encompass a wide range of species, including kangaroos , koalas , opossums , possums , Tasmanian devils , wombats , wallabies , and bandicoots , among others. Marsupials constitute
680-459: A gross communication ( corpus callosum ) between the right and left brain hemispheres. Marsupials exhibit distinct cranial features compared to placental mammals. Generally, their skulls are relatively small and compact. Notably, they possess frontal holes known as foramen lacrimale situated at the front of the orbit. Marsupials also have enlarged cheekbones that extend further to the rear, and their lower jaw's angular extension (processus angularis)
765-399: A little bigger. They are called Kusus. They have a long tail with which they hang from the trees in which they live continuously, winding it once or twice around a branch. On their belly they have a pocket like an intermediate balcony; as soon as they give birth to a young one, they grow it inside there at a teat until it does not need nursing anymore. As soon as she has borne and nourished it,
850-671: A means to prey on or a defense mechanism against large opossums. Opossums are found in North, Central, and South America . The Virginia opossum lives in regions as far north as Canada and as far south as Central America, while other types of opossums only inhabit countries south of the United States. The Virginia opossum can often be found in wooded areas, though its habitat may vary widely. Opossums are generally found in areas like forests, shrubland, mangrove swamps, rainforests and eucalyptus forests. Opossums have been found moving northward. Until
935-499: A more recent epoch, the early Miocene (roughly 20 million years ago). The last common ancestor of all living opossums dates approximately to the Oligocene -Miocene boundary (23 million years ago) and is at most no older than Oligocene in age. Many extinct metatherians, such as Alphadon , Peradectes , Herpetotherium , and Pucadelphys , were once considered to be early opossums, but it has since been recognized that this
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#17328757381761020-497: A narrow braincase , and a prominent sagittal crest . The dental formula is: 5.1.3.4 4.1.3.4 × 2 = 50 teeth. By mammalian standards, this is an unusually full jaw. The incisors are very small, the canines large, and the molars are tricuspid . Didelphimorphs have a plantigrade stance (feet flat on the ground) and the hind feet have an opposable digit with no claw . Like some New World monkeys , some opossums have prehensile tails . Like most marsupials, many females have
1105-423: A number of anatomical features that separate them from eutherians . Most female marsupials have a front pouch , which contains multiple teats for the sustenance of their young. Marsupials also have other common structural features. Ossified patellae are absent in most modern marsupials (though a small number of exceptions are reported) and epipubic bones are present. Marsupials (and monotremes ) also lack
1190-470: A pouch. The tail and parts of the feet bear scutes . The stomach is simple, with a small cecum . Like most marsupials, the male opossum has a forked penis bearing twin glandes . Although all living opossums are essentially opportunistic omnivores , different species vary in the amount of meat and vegetation they include in their diet. Members of the Caluromyinae are essentially frugivorous ; whereas
1275-461: A reproductive system that includes a bifurcated vagina and a divided uterus ; many have a marsupium , the pouch. The average estrous cycle of the Virginia opossum is about 28 days. Opossums do possess a placenta , but it is short-lived, simple in structure, and, unlike that of placental mammals, not fully functional. The young are therefore born at a very early stage, although the gestation period
1360-418: A split or double penis lying in front of the scrotum, which is not homologous to the scrotum of placental mammals. A pouch is present in most, but not all, species. Many marsupials have a permanent bag, whereas in others the pouch develops during gestation, as with the shrew opossum , where the young are hidden only by skin folds or in the fur of the mother. The arrangement of the pouch is variable to allow
1445-463: A well defined nuchal crest . Sparassodonts spanned a wide range of body sizes, from 2.2-pound (1 kg) weasel or civet -like forms to Thylacosmilus , which was the size of a leopard . Along with the Australian thylacoleonids , sparassodonts include some of the largest metatherian carnivores. Sparassodonts have highly reduced epipubic bones (pelvic bones which support the pouch ), to
1530-502: Is 3.1.3.4 3.1.3.4 , with three upper and lower incisors , one upper and lower canine , three upper and lower premolars , and four upper and lower molars in each half of either jaw. Proborhyaenids usually only have two lower incisors instead of three, except for Callistoe . Thylacosmylids have at least two upper and only two lower incisors (the uppers grew into elongated sabers ), and two upper and lower premolars. Some specimens of Borhyaena and Arctodictis are also missing
1615-556: Is an extinct order of carnivorous metatherian mammals native to South America, related to modern marsupials . They were once considered to be true marsupials, but are now thought to be a separate side branch that split before the last common ancestor of all modern marsupials. A number of these mammalian predators closely resemble placental predators that evolved separately on other continents, and are cited frequently as examples of convergent evolution . They were first described by Florentino Ameghino , from fossils found in
1700-561: Is bent inward toward the center. The hard palate of marsupials contains more openings compared to placental mammals. Teeth in marsupials also differ significantly from those in placental mammals. For instance, most Australian marsupials outside the order Diprotodontia have a varying number of incisors between their upper and lower jaws. Early marsupials had a dental formula of 5.1.3.4/4.1.3.4 per quadrant, consisting of five (maxillary) or four (mandibular) incisors, one canine, three premolars, and four molars, totaling 50 teeth. While some taxa, like
1785-662: Is evident in both brain evolution and behaviour. The extinct thylacine strongly resembled the placental wolf, hence one of its nicknames "Tasmanian wolf". The ability to glide evolved in both marsupials (as with sugar gliders ) and some placental mammals (as with flying squirrels ), which developed independently. Other groups such as the kangaroo, however, do not have clear placental counterparts, though they share similarities in lifestyle and ecological niches with ruminants . Marsupials, along with monotremes ( platypuses and echidnas ), typically have lower body temperatures than similarly sized placental mammals ( eutherians ), with
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#17328757381761870-851: Is found in South America, morphological similarities suggest it is closely related to Australian marsupials. Molecular analyses in 2010 and 2011 identified Microbiotheria as the sister group to all Australian marsupials. However, the relations among the four Australidelphid orders are not as well understood. Paucituberculata Didelphimorphia Microbiotheria Notoryctemorphia Peramelemorphia Dasyuromorphia Diprotodontia Didelphimorphia [REDACTED] Paucituberculata [REDACTED] Sparassodont † Hathliacynidae † Hondadelphidae † Borhyaenidae † Proborhyaenidae † Thylacosmilidae Sparassodonta (from Greek σπαράσσειν [ sparassein ], to tear, rend; and ὀδούς , gen. ὀδόντος [ odous , odontos ], tooth)
1955-459: Is fully reliant on its mother's milk for essential nutrients, growth factors and immunological defence. Genes expressed in the eutherian placenta that are important for the later stages of fetal development are in female marsupials expressed in their mammary glands during their lactation period instead. After this period, the joey begins to spend increasing lengths of time out of the pouch, feeding and learning survival skills. However, it returns to
2040-408: Is further divided as follows: † – Extinct Comprising over 300 extant species, several attempts have been made to accurately interpret the phylogenetic relationships among the different marsupial orders. Studies differ on whether Didelphimorphia or Paucituberculata is the sister group to all other marsupials. Though the order Microbiotheria (which has only one species, the monito del monte )
2125-922: Is high in essential fatty acids and has been used as a chest rub and a carrier for arthritis remedies given as salves. Opossum pelts have long been part of the fur trade . Caluromysiops Caluromys Glironia Hyladelphys Tlacuatzin Marmosa Monodelphis Metachirus Chironectes Lutreolina Philander Didelphis Marmosops Cryptonanus Gracilinanus Lestodelphys Thylamys Caluromysiops Caluromys Glironia Hyladelphys Tlacuatzin Marmosa Monodelphis Chironectes Marsupial Marsupials are
2210-522: Is known as a joey . Marsupials have a very short gestation period—usually between 12.5 and 33 days, but as low as 10.7 days in the case of the stripe-faced dunnart and as long as 38 days for the long-nosed potoroo . The joey is born in an essentially fetal state, equivalent to an 8–12 week human fetus, blind, furless, and small in comparison to placental newborns with sizes ranging from 4g to over 800g. A newborn marsupial can be arranged into one of three grades of developmental complexity. Those who are
2295-546: Is retracted into the body in an S-shaped curve. Neither marsupials nor monotremes possess a baculum . The shape of the glans penis varies among marsupial species. The male thylacine had a pouch that acted as a protective sheath, covering his external reproductive organs while running through thick brush. The shape of the urethral grooves of the males' genitalia is used to distinguish between Monodelphis brevicaudata , Monodelphis domestica , and Monodelphis americana . The grooves form 2 separate channels that form
2380-566: Is similar to that of many other small marsupials, at only 12 to 14 days. They give birth to litters of up to 20 young. Once born, the offspring must find their way into the marsupium, if present, to hold on to and nurse from a teat. Baby opossums, like their Australian cousins, are called joeys. Female opossums often give birth to very large numbers of young, most of which fail to attach to a teat , although as many as thirteen young can attach, and therefore survive, depending on species. The young are weaned between 70 and 125 days, when they detach from
2465-941: Is the bifurcated penis of the male and bifurcated vagina of the female (the source of the term didelphimorph , from the Greek didelphys , meaning "double-wombed"). Opossum spermatozoa exhibit sperm-pairing, forming conjugate pairs in the epididymis . This may ensure that flagella movement can be accurately coordinated for maximal motility . Conjugate pairs dissociate into separate spermatozoa before fertilization. Opossums are usually solitary and nomadic, staying in one area as long as food and water are easily available. Some families will group together in ready-made burrows or even under houses. Though they will temporarily occupy abandoned burrows, they do not dig or put much effort into building their own. As nocturnal animals, they favor dark, secure areas. These areas may be below ground or above. When threatened or harmed, they will " play possum ", mimicking
2550-687: The Maluku Islands , Timor and Sulawesi to the west of New Guinea, and in the Bismarck Archipelago (including the Admiralty Islands ) and Solomon Islands to the east of New Guinea. In the Americas, marsupials are found throughout South America, excluding the central/southern Andes and parts of Patagonia ; and through Central America and south-central Mexico, with a single species (the Virginia opossum Didelphis virginiana ) widespread in
2635-425: The chorionic villi found in eutherian placentas. The evolution of reproduction in marsupials, and speculation about the ancestral state of mammalian reproduction , have engaged discussion since the end of the 19th century. Both sexes possess a cloaca , which is connected to a urogenital sac used to store waste before expulsion. The bladder of marsupials functions as a site to concentrate urine and empties into
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2720-527: The dusky pademelon ( Thylogale brunii ), in which case this would be the earliest European record of a member of the kangaroo family ( Macropodidae ). Marsupials are taxonomically identified as members of mammalian infraclass Marsupialia, first described as a family under the order Pollicata by German zoologist Johann Karl Wilhelm Illiger in his 1811 work Prodromus Systematis Mammalium et Avium . However, James Rennie, author of The Natural History of Monkeys, Opossums and Lemurs (1838), pointed out that
2805-440: The ecological niches presently occupied by opossums were occupied by other groups of metatherians such as paucituberculatans and sparassodonts . Large opossums like Didelphis show a pattern of gradually increasing in size over geologic time as sparassodont diversity declined. Several groups of opossums, including Thylophorops , Thylatheridium , Hyperdidelphys , and sparassocynids developed carnivorous adaptations during
2890-456: The lutrine opossum and Patagonian opossum primarily feed on other animals. The water opossum or yapok ( Chironectes minimus ) is particularly unusual, as it is the only living semi-aquatic marsupial, using its webbed hindlimbs to dive in search of freshwater mollusks and crayfish. The extinct Thylophorops , the largest known opossum at 4–7 kg (8.8–15.4 lb), was a macropredator. Most opossums are scansorial , well-adapted to life in
2975-452: The postorbital bar connecting the forehead to the cheek, thus framing the eye. They exhibit marked postorbital constriction . The orbital process (between the cheek and the eye socket) is usually diminished, though the zygomatic arch (the cheekbone) is strong. They feature a prominent sagittal crest along the midline of the flattened skull, the crest strength is quite variable among borhyaenids. They have an expanded occipital bone with
3060-431: The red kangaroo , grows up to 1.8 metres (5 ft 11 in) in height and 90 kilograms (200 lb) in weight, but extinct genera, such as Diprotodon , were significantly larger and heavier. The smallest members of this group are the marsupial mice , which often reach only 5 centimetres (2.0 in) in body length. Some species resemble placental mammals and are examples of convergent evolution . This convergence
3145-1253: The " Gurlin Tsav skull " an unnamed metatherian known from a partial skull found in the Late Cretaceous Nemegt Formation of Mongolia. The following cladogram of sparassodont interrelationships is after Engelman et al. , 2020. Not all studies agree on the sister group relationship between Thylacosmilidae and Borhyaenidae recovered here, with other studies finding thylacosmilids to be within Proborhyaenidae . The relationships among hathliacynids are also relatively unstable. Allqokirus Mayulestes Patene Hondadelphys Stylocynus Cladosictis Acyon Sipalocyon Notogale Sallacyon Lycopsis longirostrus Lycopsis viverensis Lycopsis torresi Lycopsis padillai Prothylacynus Pharsophorus Borhyaena Australohyaena Arctodictis sinclairi Arctodictis munizi Callistoe Paraborhyaena Proborhyaena Eomakhaira Patagosmilus Thylacosmilus Within Metatheria ,
3230-514: The Australian continent, including mainland Australia, Tasmania, New Guinea, and nearby islands. The remaining 30% are distributed across the Americas, primarily in South America, with thirteen species in Central America and a single species, the Virginia opossum, inhabiting North America north of Mexico. Marsupials range in size from a few grams in the long-tailed planigale , to several tonnes in
3315-510: The Grenadines , the common opossum or manicou is popular and can only be hunted during certain times of the year owing to overhunting. The meat is traditionally prepared by smoking, then stewing. It is light and fine-grained, but the musk glands must be removed as part of preparation. The meat can be used in place of rabbit and chicken in recipes. Historically, hunters in the Caribbean would place
3400-925: The Santa Cruz beds of Patagonia . Sparassodonts were present throughout South America's long period of "splendid isolation" during the Cenozoic ; during this time, they shared the niches for large warm-blooded predators with the flightless terror birds . Previously, it was thought that these mammals died out in the face of competition from "more competitive" placental carnivorans during the Pliocene Great American Interchange , but more recent research has showed that sparassodonts died out long before eutherian carnivores arrived in South America (aside from procyonids , which sparassodonts probably did not directly compete with). Sparassodonts have been referred to as borhyaenoids by some authors, but currently
3485-421: The appearance and smell of a sick or dead animal. This physiological response is involuntary (like fainting), rather than a conscious act. In the case of baby opossums, however, the brain does not always react this way at the appropriate moment, and therefore they often fail to "play dead" when threatened. When an opossum is "playing possum", the animal's lips are drawn back, the teeth are bared, saliva foams around
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3570-409: The averages being 35 °C (95 °F) for marsupials and 37 °C (99 °F) for placental mammals. Some species will bask to conserve energy Marsupials' reproductive systems differ markedly from those of placental mammals . During embryonic development, a choriovitelline placenta forms in all marsupials. In bandicoots , an additional chorioallantoic placenta forms, although it lacks
3655-462: The breeding season, the male tammar wallaby 's prostate and bulbourethral gland enlarge. However, there does not appear to be any seasonal difference in the weight of the testes. Female marsupials have two lateral vaginas , which lead to separate uteri , but both open externally through the same orifice. A third canal, the median vagina, is used for birth. This canal can be transitory or permanent. Some marsupial species are able to store sperm in
3740-443: The buccal, or cheekward, side) and associated stylar cusps. In the lower molars, the trigonids (the buccal shearing side) have an inflated paracristid and marginalized or absent metaconid; and the talonid (the distal, or backendwards, crushing side) is either reduced or gone. Sparassodonts can be divided into six major groups; basal sparassodonts (?earliest Paleocene -late Miocene ), species that cannot be easily assigned to any of
3825-447: The common urogenital sinus in both females and males. Most male marsupials, except for macropods and marsupial moles , have a bifurcated penis, separated into two columns, so that the penis has two ends corresponding to the females' two vaginas. The penis is used only during copulation , and is separate from the urinary tract , but is also used during urination . It curves forward when erect, and when not erect, it
3910-581: The connection of North and South America in the late Cenozoic . The Virginia opossum is the only species found in the United States and Canada. It is often simply referred to as an opossum , and in North America it is commonly referred to as a possum ( / ˈ p ɒ s əm / ; sometimes rendered as ' possum in written form to indicate the dropped "o"). The Australasian arboreal marsupials of suborder Phalangeriformes are also called possums because of their resemblance to opossums, but they belong to
3995-411: The dangers associated with long pregnancies, as there is no need to carry a large fetus to a full term in bad seasons. Marsupials are extremely altricial animals, needing to be intensely cared for immediately following birth ( cf. precocial ). Newborn marsupials lack histologically mature immune tissues and are highly reliant on their mother's immune system for immunological protection., as well as
4080-714: The early 20th century, the Virginia opossum was widely hunted and consumed in the United States . Opossum farms have been operated in the United States in the past. Sweet potatoes were eaten together with the opossum in the American South. In 1909, a "Possum and 'Taters" banquet was held in Atlanta to honor President-elect William Howard Taft . South Carolina cuisine includes opossum, and President Jimmy Carter hunted opossums in addition to other small game. In Dominica , Grenada , Trinidad , Saint Lucia and Saint Vincent and
4165-631: The eastern United States and along the Pacific coast. The first American marsupial (and marsupial in general) that a European encountered was the common opossum . Vicente Yáñez Pinzón , commander of the Niña on Christopher Columbus ' first voyage in the late fifteenth century, collected a female opossum with young in her pouch off the South American coast. He presented them to the Spanish monarchs, though by then
4250-427: The evolutive transition from these limbs into hooves , wings , or flippers , as some groups of placental mammals have done, more difficult. However, several marsupials do possess atypical forelimb morphologies, such as the hooved forelimbs of the pig-footed bandicoot , suggesting that the range of forelimb specialization is not as limited as assumed. Joeys stay in the pouch for up to a year in some species, or until
4335-555: The extinct Diprotodon . The word marsupial comes from marsupium , the technical term for the abdominal pouch. It, in turn, is borrowed from the Latin marsupium and ultimately from the ancient Greek μάρσιππος mársippos , meaning "pouch". Marsupials have the typical characteristics of mammals —e.g., mammary glands, three middle ear bones , (and ears that usually have tragi , varying in hearing thresholds ) and true hair . There are, however, striking differences as well as
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#17328757381764420-584: The genus Varalphadon from the Late Cretaceous of North America as a basal member of Sparassodonta. However, this interpretation of Varalphadon as a sparassodont has not been supported by later phylogenetic analyses, and most of the purported synapomorphies between Varalphadon and sparassodonts are not actually present in Varalphadon or have been suggested to be due to convergent evolution. Sparassodonts have sometimes been considered closely related to
4505-425: The last upper molar, showing that the presence of this tooth was variable in these species. Sparassodonta is characterized by dental synapomorphies that distinguish the group from other closely related mammals. Unequivocal traits uniting the earliest Sparassodonts include: In borhyaenids, only the third premolar was ever replaced in the animal's lifetime, similar to other metatherians. In thylacosmilids, only
4590-519: The late Miocene- Pliocene , before the arrival of carnivorans in South America. Most of these groups, with the exception of Lutreolina , are now extinct. It has been suggested that the size and shape of the ancestral Didelphid’s jaw would most closely match that of the modern Marmosa genus. Didelphimorphs are small to medium-sized marsupials that grow to the size of a house cat. They tend to be semi- arboreal omnivores , although there are many exceptions. Most members of this order have long snouts ,
4675-454: The latest review of the group, that of Prevosti and Forasiepi (2018), with additions from more recent studies. Although Mayulestes was originally described as a sparassodont, later phylogenetic analyses have shown that it most likely does not belong to this group; however more recent studies show it to be closely related to sparassodonts. Similarly, while basal borhyaenoids such as Lycopsis and Prothylacynus were once thought to belong to
4760-401: The least developed at birth are found in dasyurids , intermediate ones are found in didelphids and peramelids , and the most developed are in macropods . Despite the lack of development it crawls across its mother's fur to make its way into the pouch , which acts like an external womb , where it latches onto a teat for food. It will not re-emerge for several months, during which time it
4845-405: The lower third premolar was replaced. The cusps of the sparassodont molar correlate to a cutting function rather than a crushing one. In the upper molars, the paracone (on the lingual, or tongueward, side) is reduced and fused to the metacone (distal, towards the back of the mouth), inflating the postmetacrista (the lingual border of the metacone); and they almost always lack the stylar shelf (on
4930-625: The marsupium. There they remain for a number of weeks, attached to the teat. The offspring are eventually able to leave the marsupium for short periods, returning to it for warmth, protection, and nourishment. Prenatal development differs between marsupials and placental mammals . Key aspects of the first stages of placental mammal embryo development, such as the inner cell mass and the process of compaction, are not found in marsupials. The cleavage stages of marsupial development are very variable between groups and aspects of marsupial early development are not yet fully understood. An infant marsupial
5015-402: The milk. Newborn marsupials must climb up to their mother's teats and their front limbs and facial structures are much more developed than the rest of their bodies at the time of birth. This requirement has been argued to have resulted in the limited range of locomotor adaptations in marsupials compared to placentals. Marsupials must develop grasping forepaws during their early youth, making
5100-437: The mother becomes pregnant again. From the start of the 17th century, more accounts of marsupials arrived. For instance, a 1606 record of an animal, killed on the southern coast of New Guinea, described it as "in the shape of a dog, smaller than a greyhound", with a snakelike "bare scaly tail" and hanging testicles. The meat tasted like venison , and the stomach contained ginger leaves. This description appears to closely resemble
5185-503: The mother's teat. Once inside the mouth, a bulbous swelling on the end of the teat attaches it to the offspring till it has grown large enough to let go. In species without pouches or with rudimentary pouches these are more developed than in forms with well-developed pouches, implying an increased role in maintaining the young attached to the mother's teat. In Australasia, marsupials are found in Australia, Tasmania and New Guinea; throughout
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#17328757381765270-420: The mouth, the eyes close or half-close, and a foul-smelling fluid is secreted from the anal glands . The stiff, curled form can be prodded, turned over, and even carried away without reaction. The animal will typically regain consciousness after a period of a few minutes to four hours, a process that begins with a slight twitching of the ears. Some species of opossums have prehensile tails , although dangling by
5355-427: The muscular approach to the movement of the hind limbs. This could be explained by an original feature of mammals, as these epipubic bones are also found in monotremes . Marsupial reproductive organs differ from the placental mammals. For them, the reproductive tract is doubled. The females have two uteri and two vaginas, and before birth, a birth canal forms between them, the median vagina. In most species, males have
5440-414: The next joey is born. A marsupial joey is unable to regulate its body temperature and relies upon an external heat source. Until the joey is well-furred and old enough to leave the pouch, a pouch temperature of 30–32 °C (86–90 °F) must be constantly maintained. Joeys are born with "oral shields", which consist of soft tissue that reduces the mouth opening to a round hole just large enough to accept
5525-446: The offspring to receive maximum protection. Locomotive kangaroos have a pouch opening at the front, while many others that walk or climb on all fours have the opening in the back. Usually, only females have a pouch, but the male water opossum has a pouch that is used to accommodate his genitalia while swimming or running. Marsupials have adapted to many habitats, reflected in the wide variety in their build. The largest living marsupial,
5610-482: The opossum as a "beast in bigness of a pig and in taste alike," while Smith recorded it "hath an head like a swine ... tail like a rat ... of the bigness of a cat." The Powhatan word ultimately derives from a Proto-Algonquian word ( *wa·p-aʔθemwa ) meaning "white dog or dog-like beast." Following the arrival of Europeans in Australia , the term possum was borrowed to describe distantly related Australian marsupials of
5695-456: The opossum, retain this original tooth count, others have reduced numbers. For instance, members of the Macropodidae family, including kangaroos and wallabies, have a dental formula of 3/1 – (0 or 1)/0 – 2/2 – 4/4. Many marsupials typically have between 40 and 50 teeth, which is notably more than most placental mammals. Notably, in marsupials, the second set of teeth only grows in at the site of
5780-528: The other sparassodont groups and whose teeth often exhibit adaptations for omnivory ; hathliacynids (late Oligocene -early Pliocene /late Pliocene), which range from a marten to a thylacine in size, and have long, fox-like muzzles and teeth strongly suited for carnivory ; basal borhyaenoids (middle Eocene -late Miocene), borhyaenoids which are unable to be easily classified into the families Borhyaenidae , Thylacosmilidae , or Proborhyaenidae and range in form and size; borhyaenids (early-late Miocene),
5865-432: The oviduct after mating. Marsupials give birth at a very early stage of development; after birth, newborn marsupials crawl up the bodies of their mothers and attach themselves to a teat, which is located on the underside of the mother, either inside a pouch called the marsupium , or open to the environment. Mothers often lick their fur to leave a trail of scent for the newborn to follow to increase chances of making it into
5950-508: The placement of five different groups of mammals – monkeys , lemurs , tarsiers , aye-ayes and marsupials (with the exception of kangaroos, that were placed under the order Salientia) – under a single order (Pollicata) did not appear to have a strong justification. In 1816, French zoologist George Cuvier classified all marsupials under the order Marsupialia. In 1997, researcher J. A. W. Kirsch and others accorded infraclass rank to Marsupialia. With seven living orders in total, Marsupialia
6035-452: The point that early analysis could not even find evidence for them. This is a characteristic shared with the Australian thylacine , and historically argued as a synapomorphy , though nowadays it is considered to have developed independently for poorly understood reasons. As with thylacines, it is very likely that they possessed long cartilaginous elements instead. The dental formula of sparassodonts varies considerably. In borhyaenids, it
6120-430: The pouch to sleep, and if danger threatens, it will seek refuge in its mother's pouch for safety. An early birth removes a developing marsupial from its mother's body much sooner than in placental mammals; thus marsupials have not developed a complex placenta to protect the embryo from its mother's immune system . Though early birth puts the tiny newborn marsupial at greater environmental risk, it significantly reduces
6205-425: The sparassodont group most specialized for running, but not as much as living carnivorans or even thylacines ; proborhyaenids (middle Eocene-late Oligocene ), robust, wolverine -like forms with ever-growing upper and lower canines ; and thylacosmilids (early Miocene-late Pliocene), another terrestrially specialized group with ever-growing saber-like upper canines . The taxonomic classification below follows
6290-416: The suborder Phalangeriformes , which are more closely related to other Australian marsupials such as kangaroos. They similarly have didelphimorphia, two ( di ) wombs ( delphus ). Opossums are often considered to be " living fossils ", and as a result they are often used to approximate the ancestral therian condition in comparative studies. But this is a mistake, because the oldest opossum fossils are from
6375-423: The tail is more common among juveniles. An opossum may also use its tail as a brace and a fifth limb when climbing. The tail is occasionally used as a grip to carry bunches of leaves or bedding materials to the nest. A mother will sometimes carry her young upon her back, where they will cling tightly even when she is climbing or running. Threatened opossums (especially males) will growl deeply, raising their pitch as
6460-406: The teat and leave the pouch. The opossum lifespan is unusually short for a mammal of its size, usually only one to two years in the wild and as long as four or more years in captivity. Senescence is rapid. Opossums are moderately sexually dimorphic with males usually being larger, heavier, and having larger canines than females. The largest difference between the opossum and non-marsupial mammals
6545-570: The term Borhyaenoidea refers to a restricted subgroup of sparassodonts comprising borhyaenids and their close relatives. Almost all sparassodonts have an exceptionally shortened snout—most especially thylacosmylids. Hathliacynids usually have a longer snout than the other groups. The nasal bones extend past the eye sockets , often reaching the lacrimal bone . Except for thylacosmylids beyond Patagosmilus , sparassodonts feature an open eye socket, with more marginalized (though nonetheless prominent) postorbital processes which would otherwise form
6630-459: The third premolar and posteriorly; all teeth anterior to this erupt initially as permanent teeth. Few general characteristics describe their skeleton. In addition to unique details in the construction of the ankle, epipubic bones ( ossa epubica ) are observed projecting forward from the pubic bone of the pelvis. Since these are present in males and pouchless species, it is believed that they originally had nothing to do with reproduction, but served in
6715-433: The threat becomes more urgent. Males make a clicking "smack" noise out of the side of their mouths as they wander in search of a mate, and females will sometimes repeat the sound in return. When separated or distressed, baby opossums will make a sneezing noise to signal their mother. The mother in return makes a clicking sound and waits for the baby to find her. If threatened, the baby will open its mouth and quietly hiss until
6800-405: The threat is gone. Opossums eat insects, rodents , birds, eggs, frogs, plants, fruits and grain. Some species may eat the skeletal remains of rodents and roadkill animals to fulfill their calcium requirements. In captivity, opossums will eat practically anything including dog and cat food, livestock fodder and discarded human food scraps and waste. Many large opossums (Didelphini) are immune to
6885-500: The trees or on the ground, but members of the Caluromyinae and Glironiinae are primarily arboreal, whereas species of Metachirus , Monodelphis , and to a lesser degree Didelphis show adaptations for life on the ground. Metachirus nudicaudatus , found in the upper Amazon basin , consumes fruit seeds, small vertebrate creatures like birds and reptiles and invertebrates like crayfish and snails , but seems to be mainly insectivorous . As marsupials, female opossums have
6970-554: The venom of rattlesnakes and pit vipers ( Crotalinae ) and regularly prey upon these snakes. This adaptation seems to be unique to the Didelphini, as their closest relative, the brown four-eyed opossum , is not immune to snake venom. Similar adaptations are seen in other small predatory mammals such as mongooses and hedgehogs . Didelphin opossums and crotaline vipers have been suggested to be in an evolutionary arms race . Some authors have suggested that this adaptation originally arose as
7055-472: The ventral and dorsal folds of the erectile tissue. Several species of dasyurid marsupials can also be distinguished by their penis morphology. The only accessory sex glands marsupials possess are the prostate and bulbourethral glands . Male marsupials have 1-3 pairs of bulbourethral glands. There are no ampullae of vas deferens , seminal vesicles or coagulating glands. The prostate is proportionally larger in marsupials than in placental mammals. During
7140-547: The young were lost and the female had died. The animal was noted for its strange pouch or "second belly", and how the offspring reached the pouch was a mystery. On the other hand, it was the Portuguese who first described Australasian marsupials. António Galvão , a Portuguese administrator in Ternate (1536–1540), wrote a detailed account of the northern common cuscus ( Phalanger orientalis ): Some animals resemble ferrets, only
7225-484: Was solely on the basis of plesiomorphies ; they are now considered to belong to older branches of Metatheria that are only distantly related to modern opossums. Opossums probably originated in the Amazonia region of northern South America, where they began their initial diversification. They were minor components of South American mammal faunas until the late Miocene, when they began to diversify rapidly. Before that time,
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