The opossum is a marsupial of the order Didelphimorphia endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 103 or more species in 19 genera. Opossums originated in South America and entered North America in the Great American Interchange following the connection of the two continents, their unspecialized biology, flexible diet, reproductive habits make them successful colonizers and survivors in diverse locations and conditions. Although the animal is called a possum in North America, which would refer to the Virginia opossum species, it should not be confused with the suborder Phalangeriformes, which are arboreal marsupials in the Eastern Hemisphere called "possums" because of their resemblance to Didelphimorphia; the word "opossum" is borrowed from the Powhatan language and was first recorded between 1607 and 1611 by John Smith and William Strachey. Both men encountered the language at the British settlement of Jamestown, which Smith helped to found and where Strachey served as its first secretary.
Strachey's notes describe 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 derives from a Proto-Algonquian word 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 the suborder Phalangeriformes, which are more related to other Australian marsupials such as kangaroos. "Didelphimorphia" refers to the fact. Didelphimorphs are small to medium-sized marsupials, they tend to be semi-arboreal omnivores. Most members of this taxon have long snouts, a narrow braincase, a prominent sagittal crest; the dental formula is: 184.108.40.206.1.3.4 × 2 = 50 teeth. By mammalian standards, this is an unusually full jaw; the incisors are small, the canines large, the molars are tricuspid. Didelphimorphs have a plantigrade stance and the hind feet have an opposable digit with no claw.
Like some New World monkeys, opossums have prehensile tails. Like that of all marsupials, the fur consists of awn hair only, the females have 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 opportunistic omnivores, different species vary in the amount of meat and vegetation they include in their diet. Members of the Caluromyinae are frugivorous; the yapok is 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, was a macropredator. Most opossums are scansorial, well-adapted to life in the trees or on the ground, but members of the Caluromyinae and Glironiinae are arboreal, whereas species of Metachirus, to a lesser degree Didelphis show adaptations for life on the ground; the 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 most insectivorous.
As a marsupial, the female opossum has a reproductive system that includes a bifurcated vagina, a divided uterus and a marsupium, her pouch. The average estrous cycle of the opossum is about 28 days. Opossums do possess a placenta, but it is short-lived, simple in structure, unlike that of placental mammals, not functional; the young are therefore born at a early stage, although the gestation period is similar to that of many other small marsupials, at only 12 to 14 days. Once born, the offspring must find their way into the marsupium to hold on to and nurse from a teat. Baby opossums, like their Australian cousins, are called joeys. Female opossums give birth to large numbers of young, most of which fail to attach to a teat, although as many as thirteen young can attach, therefore survive, depending on species; the young are weaned between 125 days, when they detach from the teat and leave the pouch. The opossum lifespan is unusually short for a mammal of its size only one to two years in the wild and as long as four or more years in captivity.
Senescence is rapid. The species are moderately sexually dimorphic with males being larger, much heavier, having larger canines than females; the largest difference between the opossum and non-marsupial mammals is the bifurcated penis of the male and bifurcated vagina of the female. Opossum spermatozoa exhibit sperm-pairing; this may ensure that flagella movement can be coordinated for maximal motility. Conjugate pairs dissociate into separate spermatozoa before fertilization. Opossums are solitary and nomadic, staying in one area as long as food and water are available; some families will group together in ready-made burrows or 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 secure areas. These areas may be below ground or above; when threatened or harmed, they will "play possum", mimicking the app
Petauroidea is a superfamily of marsupials from Australia and New Guinea. It is part of the suborder Phalangeriformes within the order Diprotodontia, which includes, among others, kangaroos, cuscuses; the superfamily Phalangeroidea, including cuscuses and brushtail possums and pygmy possums, is the immediate sister group of the Petauroidea. The superfamily includes the following recent species: Superfamily Petauroidea Family Pseudocheiridae Subfamily Hemibelideinae Genus Hemibelideus Lemur-like ringtail possum, Hemibelideus lemuroides Genus Petauroides Greater glider, Petauroides volans Subfamily Pseudocheirinae Genus Petropseudes Rock-haunting ringtail possum, Petropseudes dahli Genus Pseudocheirus Common ringtail possum, Pseudocheirus peregrinus Genus Pseudochirulus Lowland ringtail possum, Pseudochirulus canescens Weyland ringtail possum, Pseudochirulus caroli Cinereus ringtail possum, Pseudochirulus cinereus Painted ringtail possum, Pseudochirulus forbesi Herbert River ringtail possum, Pseudochirulus herbertensis Masked ringtail possum, Pseudochirulus larvatus Pygmy ringtail possum, Pseudochirulus mayeri Vogelkop ringtail possum, Pseudochirulus schlegeli Subfamily Pseudochiropinae Genus Pseudochirops D'Albertis' ringtail possum, Pseudochirops albertisii Green ringtail possum, Pseudochirops archeri Plush-coated ringtail possum, Pseudochirops corinnae Reclusive ringtail possum, Pseudochirops coronatus Coppery ringtail possum, Pseudochirops cupreus Family Petauridae Genus Dactylopsila Great-tailed triok, Dactylopsila megalura Long-fingered triok, Dactylopsila palpator Tate's triok, Dactylopsila tatei Striped possum, Dactylopsila trivirgata Genus Gymnobelideus Leadbeater's possum, Gymnobelideus leadbeateri Genus Petaurus Northern glider, Petaurus abidi Yellow-bellied glider, Petaurus australis Biak glider, Petaurus biacensis Sugar glider, Petaurus breviceps Mahogany glider, Petaurus gracilis Squirrel glider, Petaurus norfolcensis Family Tarsipedidae Genus Tarsipes Honey possum or Noolbenger, Tarsipes rostratus Family Acrobatidae Genus Acrobates Feathertail glider, Acrobates pygmaeus Genus Distoechurus Feather-tailed possum, Distoechurus pennatus Groves, C.
P. 2005. Order Diprotodontia. Pp. 43–70 in Wilson, D. E. & Reeder, D. M.. Mammal Species of the World: a taxonomic and geographic reference. 3rd ed. Baltimore: The Johns Hopkins University Press, 2 vols. 2142 pp. ISBN 978-0-8018-8221-0
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
The order Peramelemorphia includes the bandicoots and bilbies. All members of the order are endemic to the twin land masses of Australia-New Guinea and most have the characteristic bandicoot shape: a plump, arch-backed body with a long, delicately tapering snout large upright ears long, thin legs, a thin tail, their size varies from about 140 grams up to 4 kilograms, but most species are about one kilogram, or the weight of a half-grown kitten. The position of the Peramelemorphia within the marsupial family tree has long been puzzling and controversial. There are two morphological features in the order that appear to show a clear evolutionary link with another marsupial group: the type of foot, the teeth; these clear signposts point in opposite directions. All members of the order are polyprotodont -- in the case of three pairs; this suggests. On the other hand, they have an unusual feature in their feet: the second and third toes are fused together; this condition is called syndactyly, is characteristic of the Diprotodontia.
Attempts to resolve this puzzle include the view that the bandicoot group evolved from the carnivores, retaining the polyprotodont dentition, independently evolving a syndactyl hind foot. A third view suggests that the bandicoot group evolved from a primitive carnivore, developed the syndactylous hind foot as a specialisation for climbing, the diprotodonts split off and evolved the two-tooth jaw that gives them their name. Recent molecular level investigations do not so far appear to have resolved the puzzle, but do suggest that whatever the relationship of the bandicoot group to the other marsupial orders may be, it is a distant one. Recent molecular analyses have resulted in a phylogenetic reconstruction of the members of Peramelemorphia with quite strong support; the most basal split separates Thylacomyidae from all other bandicoots. The next to diverge was the extinct Chaeropodidae; the remaining taxa comprise the Peramelidae, which divides into subfamilies Peramelinae and a clade in which the Echymiperinae form a sister group to Peroryctinae: Many specimens of modern peramelemorphian have been recovered in the fossil record from Pleistocene and Holocene fossil localities.
However few fossil species have been recovered to date. The first species of fossil peramelemorphian was described by R. A. Stirton in 1955; the specimen Stirton described was a partial lower jaw from the Tirari Desert in Central Australia, Pliocene in age. The lower jaw morphology suggested a relationship with bilbies, was named Ischnodon australis, it was not until 1976 that Wade described the next fossil bandicoot. A single upper molar was recovered from the Bluff Downs fossil site, Allingham Formation, in northern Queensland Pliocene in age; the tooth was similar to that of species of Perameles, was therefore named Perameles allinghamensis. In 1995, the first Miocene species was described from Riversleigh, was named Yarala burchfieldi by Dr Jeannette Muirhead; the species was represented by several upper and lower jaws, which were smaller than any living bandicoots and had a primitive dentition. A skull was recovered in 2000, the first for any fossil peramelemorphian to date. Features of the skull and dentition suggested that Yarala burchfieldi was distinct from other peramelemorphians, for this reason, a new Superfamily Yaraloidea and Family Yaralidae were erected to classify this species.
In 1997, Muirhead and Archer described a new species of Perameles, Perameles bowensis, from teeth recovered from two Pliocene fossil localities and Wellington Caves. The same species was reported in 2000 from Chinchilla, Queensland by Mackness and colleagues. In 2002, Price described a new species Perameles, Perameles sobbei, from the Darling Downs, south-eastern Queensland; this species was represented by a few isolated lower molars. Additional material were described in 2005 from the same site, including upper molars. A second species of Yarala, Yarala kida, was described in 2006 by Schwartz; this species was recovered from Kangaroo Well, a late Oligocene site from the Northern Territory in Australia. This species is thought to be more primitive than Yarala burchfieldi; the second fossil skull of any fossil peramelemorphian was recovered from Miocene sites of Riversleigh. In fact, more than one skull of this new species was found, was different from any other bandicoot to erect a new genus, Galadi.
The species was named Galadi speciosus by colleagues. It was short-snouted unlike modern bandicoots suggesting that it was more carnivorous than its omnivorous modern relatives, its relationship to other bandicoots is unclear, but it was to be less primitive than Yarala but more primitive than living bandicoots. An additional three species of Galadi were described in 2013 and named Galadi grandis, Galadi amplus and Galadi adversus. Gurovich et al. described a new species of mouse-sized bandicoot from Riversleigh and from Kutjamarpu, Southern Australia. The species, named B
In phylogenetics, basal is the direction of the base of a rooted phylogenetic tree or cladogram. The term may be more applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root; each node in the tree corresponds to a clade. The terms deep-branching or early-branching are similar in meaning. While there must always be two or more basal clades sprouting from the root of every cladogram, those clades may differ in taxonomic rank and/or species diversity. If C is a basal clade within D that has the lowest rank of all basal clades within D, C may be described as the basal taxon of that rank within D. Greater diversification may be associated with more evolutionary innovation, but ancestral characters should not be imputed to the members of a less species-rich basal clade without additional evidence, as there can be no assurance such an assumption is valid. In general, clade A is more basal than clade B if B is a subgroup of the sister group of A.
Within large groups, "basal" may be used loosely to mean'closer to the root than the great majority of', in this context terminology such as "very basal" may arise. A'core clade' is a clade representing all but the basal clade of lowest rank within a larger clade. A basal group in the stricter sense forms a sister group to the rest of the larger clade, as in the following case: While it is easy to identify a basal clade in such a cladogram, the appropriateness of such an identification is dependent on the accuracy and completeness of the diagram, it is assumed in this example that the terminal branches of the cladogram depict all the extant taxa of a given rank within the clade. Additionally, this qualification does not ensure. In phylogenetics, the term basal can be objectively applied to clades of organisms, but tends to be applied selectively and more controversially to groups or lineages thought to possess ancestral characters, or to such presumed ancestral traits themselves. In describing characters, "ancestral" or "plesiomorphic" are preferred to "basal" or "primitive", the latter of which may carry false connotations of inferiority or a lack of complexity.
Despite the ubiquity of the usage of basal, some systematists believe its application to extant groups is unnecessary and misleading. The term is more applied when one branch is less diverse than another branch; the term may be equivocal in that it refers to the direction of the root of the tree, which represents a hypothetical ancestor. An extant basal group may or may not resemble the last common ancestor of a larger clade to a greater degree than other groups, is separated from that ancestor by the same amount of time as all other extant groups. However, there are cases where the unsually small size of a sister group does indeed correlate with an unusual number of ancestral traits, as in Amborella. Other famous examples of this phenomenon are the oviparous reproduction and nipple-less lactation of monotremes, a basal clade of mammals with just five species, the archaic anatomy of the tuatara, a basal clade of lepidosaurian with a single species; the flowering plant family Amborellaceae, restricted to New Caledonia in the southwestern Pacific, is a basal clade of extant angiosperms, consisting of the most basal species, genus and order within the group.
The traits of Amborella trichopoda are regarded as providing significant insight into the evolution of flowering plants. However, those traits are a mix of archaic and apomorphic features that have only been sorted out via comparison with other angiosperms and their positions within the phylogenetic tree. Within the primate family Hominidae, gorillas are a sister group to common chimpanzees and humans; these five species form the subfamily Homininae, of which Gorilla is the basal genus. However, if the analysis is not restricted to genera, the Homo plus Pan clade is basal. Moreover, orangutans are a sister group to Homininae and are the basal genus in the family as a whole. Subfamilies Homininae and Ponginae are both basal within Hominidae, but given that there are no nonbasal subfamilies in the cladogram it is unlikely the term would be applied to either. In general, a statement to the effect that one group is basal, or branches off first, within another group may not make sense unless the appropriate taxonomic level is specified.
If that level cannot be specified a more detailed description of the relevant sister groups may be needed. In this example, orangutans differ from the other genera in their Asian range; this fact plus their basal status provides a hint that the most recent common ancestor of extant great apes may have been Eurasian, a suggestion, consistent with other evidence. Orangutans differ from African apes in their more arboreal lifestyle, a
Numbat – Myrmecobius fasciatus – is an insectivorous marsupial native to Western Australia and re-introduced to South Australia. The species is known as noombat or walpurti, its diet consists exclusively of termites. Once widespread across southern Australia, its range is now restricted to several small colonies and it is listed as an endangered species; the numbat protected by conservation programs. The numbat genus Myrmecobius is the sole member of the family Myrmecobiidae, one of the four families that make up the order Dasyuromorphia, the Australian marsupial carnivores; the species is not related to other extant marsupials. A closer affinity with the extinct thylacine, contained in the same order, has been proposed. Genetic studies have shown the ancestors of the numbat diverged from other marsupials between 32 and 42 million years ago, during the late Eocene. Two subspecies have been described, but one of these—the rusty coloured Myrmecobius fasciatus rufus Finlayson, 1933,—has been extinct since at least the 1960s, only the nominate subspecies remains alive today.
The population described by Finlayson occurred in the arid central regions of South Australia, he thought they had once extended to the coast. The separation to subspecies was not recognised in the national census of Australian mammals, following W. D. L. Ride and others, As its name implies, M. fasciatus rufus had a more reddish coat than the surviving population. Only a small number of fossil specimens are known, the oldest dating back to the Pleistocene, no other species from the same family have identified; the following is a phylogenetic tree based on mitochondrial genome sequences: The common names are adopted from the extant names at the time of English colonisation, from the Nyungar language of southwest Australia, walpurti, the name in the Pitjantjatjara dialect. The orthography and pronunciation of the Nyungar name is regularised, following a survey of published sources and contemporary consultation that resulted in the name noombat, pronounced noom'bat. Other names include marsupial anteater.
The numbat is a small, colourful creature between 35 and 45 centimetres long, including the tail, with a finely pointed muzzle and a prominent, bushy tail about the same length as its body. Colour varies from soft grey to reddish-brown with an area of brick red on the upper back, always with a conspicuous black stripe running from the tip of the muzzle through the eyes to the bases of the small, round-tipped ears. Between four and eleven white stripes cross the animal's hindquarters, which become fainter towards the midback; the underside is cream or light grey, while the tail is covered with long, grey hair flecked with white. Weight varies between 700 g. Unlike most other marsupials, the numbat is diurnal because of the constraints of having a specialised diet without having the usual physical equipment for it. Most ecosystems with a generous supply of termites have a large creature with powerful forelimbs bearing heavy claws. Numbats are not large, they have five toes on the fore feet, four on the hind feet.
However, like other mammals that eat termites or ants, the numbat has a degenerate jaw with up to 50 small, nonfunctional teeth, although it is able to chew does so, because of the soft nature of its diet. Uniquely among terrestrial mammals, an additional cheek tooth is located between the premolars and molars; as a result, although not all individuals have the same dental formula, in general, it follows the unique pattern: 220.127.116.11.18.104.22.168.4Like many ant or termite eating animals, the numbat has a long and narrow tongue coated with sticky saliva produced by large submandibular glands. A further adaptation to the diet is the presence of numerous ridges along the soft palate, which help to scrape termites off the tongue so they can be swallowed; the digestive system is simple, lacks many of the adaptations found in other entomophagous animals because termites are easier to digest than ants, having a softer exoskeleton. Numbats are able to gain a considerable amount of water from their diets, since their kidneys lack the usual specialisations for retaining water found in other animals living in their arid environment.
Numbats possess a sternal scent gland, which may be used for marking their territories. Although the numbat finds termite mounds using scent, it has the highest visual acuity of any marsupial, unusually for marsupials, has a high proportion of cone cells in the retina; these are both adaptations for its diurnal habits, vision does appear to be the primary sense used to detect potential predators. Numbats are able to enter a state of torpor, which may last up to fifteen hours a day during the winter months. Numbats were widely distributed across southern Australia, from Western Australia to north-western New South Wales. However, their range has decreased since the arrival of Europeans, the species has survived only in two small patches of land in the Dryandra Woodland and the Perup Nature Reserve, both in Western Australia. In recent years, however, it has been reintroduced into a few fenced reserves, including some in South Australia and New South Wales. Today, numbats are found only in areas of eucalypt forest, but they were once more widespread in