The mammals of Australia have a rich fossil history, as well as a variety of extant mammalian species, dominated by the marsupials, but also including monotremes and placentals. The marsupials evolved to fill specific ecological niches, and in many cases they are physically similar to the placental mammals in Eurasia and North America that occupy similar niches, a phenomenon known as convergent evolution.[1] For example, the top mammalian predators in Australia, the Tasmanian tiger and the marsupial lion, bore a striking resemblance to large canids such as the gray wolf and large cats respectively; gliding possums and flying squirrels have similar adaptations enabling their arboreal lifestyle; and the numbat and anteaters are both digging insectivores. Most of Australia's mammals are herbivores or omnivores.
The indisputable remains of Australian placental mammals started from the Miocene, when Australia moved closer to Indonesia. After 15 myabats appeared reliably in the fossil record, and after 5to10 myarodents did. The subsequent introductions of placental mammals into Australian fauna were about 1 mya (rats), 40,000 years ago (homo sapiens),[5] several thousand years ago (dingo), and 200 years ago from European colonization (many species); the last two were made by humans.[citation needed]
Some claims were made about placental mammal fossils from the Eocene of Australia,[6] called Tingamarra. These claims are based on only one found tooth having some characteristic features of condylarth, and were discussed widely. But both the age and placental nature of these fossils were challenged by other researchers.[3][4]
Monotremes and marsupials
Monotremes are mammals with a unique method of reproduction: they lay eggs instead of giving birth to live young. Two of the five known living species of monotreme occur in Australia: the platypus and the short-beaked echidna. The platypus — a venomous, egg-laying, duck-billed, amphibious mammal — is one of the strangest creatures in the animal kingdom. When a platypus pelt was first presented by Joseph Banks to English naturalists in the late 18th century, they were convinced it must be a cleverly created hoax. Another strange monotreme is the short-beaked echidna; covered in hairy spikes, with a tubular snout in the place of a mouth, it has a tongue that can move in and out of the snout about 100 times per minute to capture termites.
Australia is also home to the world's largest and most diverse selection of marsupials: mammals with a pouch in which they rear their young. The marsupial carnivores— order Dasyuromorphia— are represented by two surviving families: the Dasyuridae with 51 members, and the Myrmecobiidae with the numbat as its sole surviving member.
The thylacine, or Tasmanian tiger, was the largest Dasyuromorphia and the last living specimen of the family Thylacinidae; however, the last known specimen died in captivity in 1936. The world's largest surviving carnivorous marsupial is the Tasmanian devil; it is the size of a small dog and hunts although it is opportunistic. It became extinct on the mainland some 600 years ago and is now found only in Tasmania. There are four species of quoll, or native cats, all of which are threatened species. The remainder of the Dasyuridae are referred to as "marsupial mice"; most weigh less than 100 grams (3+1⁄2oz). There are two species of marsupial mole— order Notoryctemorphia— that inhabit the deserts of Western Australia. These rare, blind, earless carnivores spend most of their time underground; little is known about them.
The marsupial omnivores include the bandicoots and bilbies, order Peramelemorphia. There are seven species in Australia, most of which are endangered. These small creatures share several characteristic physical features: a plump, arch-backed body with a long, delicately tapering snout, large upright ears, long thin legs, and a thin tail. The evolutionary origin of this group is unclear, but they share characteristics from both carnivorous and herbivorous marsupials.
The koala does not normally need to drink because it can obtain all of the moisture it needs by eating leaves.
The marsupial herbivores are classified in the order Diprotodontia, and further into the suborders Vombatiformes, Phalangeriformes and Macropodiformes. The Vombatiformes include the koala and the three species of wombat. One of Australia's best-known marsupials, the koala is an arboreal (tree-dwelling) species that feeds on the leaves of some 120 species of eucalyptus. Wombats, on the other hand, live on the ground and feed on grasses, sedges and roots. Wombats use their rodent-like front teeth and powerful claws to dig extensive burrow systems; they are mainly crepuscular and nocturnal. Wombats are also well known for their backwards facing pouches. Also among this group is the marsupial lion, which went extinct after the arrival of aboriginals, and was one of the few carnivorous vombatiforms.
The Phalangeriformes includes possums and is a diverse group of arboreal marsupials, including six families and 26 species. They vary in size from the pygmy possum, weighing just 7 grams (1⁄4oz), to the cat-sized common ringtail and brushtail possums. The sugar and squirrel gliders are common species of gliding possum, found in the eucalyptus forests of eastern Australia, while the feathertail glider is the smallest glider species. The gliding possums have membranes, called "patagia", that extend from the fifth finger of their forelimb back to the first toe of their hind foot. These membranes, when outstretched, allow them to glide between trees.
The Macropodiformes are divided into three families that are found in all Australian environments except alpine areas: the Hypsiprymnodontidae, with the musky rat-kangaroo as its only member; the Potoroidae, with 10 species; and the Macropodidae which had 53 members in Australia, but some species are extinct. The Potoroidae include the bettongs, potaroos and rat-kangaroos, small species that make nests and carry plant material with their tails. The Macropodiae include kangaroos, wallabies and associated species; size varies widely within this family. Most macropods move in a bipedal, energy-efficient hopping motion. They have powerfully muscled tails and large hind legs with long narrow hind feet. The hind feet have a distinctive arrangement of four toes, while the short front legs have five separate digits. The musky rat-kangaroo is the smallest macropod and the only species that is not bipedal, while the male red kangaroo is the largest, reaching a height of about 2 metres (6ft 7in) and weighing up to 85 kilograms (187lb).
Placental mammals
The dingo was the first placental mammal introduced to Australia by humans.
Australia has indigenous placental mammals from two orders: the bats, order Chiroptera, represented by six families, and the mice and rats, order Rodentia, family Muridae. Bats and rodents are relatively recent arrivals to Australia. Bats probably arrived from Asia, and they are present in the fossil record only from as recently as 15 mya. Although 7% of the world's bats species live in Australia, there are only two endemic genera of bats. Rodents first arrived in Australia 5to10 mya and underwent a wide radiation to produce the species collectively known as the "old endemics". The old endemics are represented by 14 extant genera. About a million years ago, the rat entered Australia from New Guinea and evolved into seven species of Rattus, collectively called the "new endemics".
Since human settlement, many placental mammals have been introduced to Australia and are now feral. The first was the dingo; fossil evidence suggests that people from the north brought the dingo to Australia about 5000 years ago.[7] When Europeans settled Australia they intentionally released many species into the wild, including the red fox, brown hare, and the European rabbit. Other domestic species have escaped and over time have produced wild populations, including the cat, fallow deer, rusa deer, chital, domestic horse, donkey, pig, domestic goat, water buffalo, and dromedary. Only three species of Australia's non-indigenous placental mammals were not deliberately introduced: the house mouse, black rat and brown rat.
Australian waters are home to the endangered dugong.
Forty-six species of marine mammals from the order Cetacea are found in Australian coastal waters, but since many of these species have a global distribution, some authors do not consider them Australian species. There are nine species of baleen whale, including the enormous humpback whales and southern right whales. Dwarf minke whales are common off Great Barrier Reef in winter. There are 37 species of toothed whale, which include all six genera of the family Ziphiidae (beaked whales), and 21 species of oceanic dolphin, including the Australian snubfin dolphin, a species first described in 2005 that is endemic to Australia. Some oceanic dolphins, such as the orca, can be found in all waters around the continent; others, such as the Irrawaddy dolphin, are confined to the warm northern waters. The dugong (order Sirenia) is an endangered marine species that inhabits the waters of northeastern and northwestern Australia, particularly the Torres Strait. It can grow up to 3 metres (9.8ft) long and weigh as much as 400 kilograms (880lb). The dugong is the only herbivorous marine mammal in Australia, feeding on sea grass in coastal areas.
Ten species of seals and sea lions (parvorder Pinnipedia) live off the southern Australian coast and in Sub-Antarctic Australian territories.
Conserving Australian Mammals
The distinctive nature of Australia's mammalian fauna, with a high rate of endemism, underscores the global significance of these conservation efforts. Key strategies include the creation of Safe Havens or predator-free areas providing a refuge from predators such as cats and foxes, which are responsible for the decline of many native species. Habitat Protection and Restoration. Conservation efforts focus on managing national parks, reserves, and private conservation areas to support the natural ecosystems required by various species. This includes activities like reforestation, erosion control, and management of fire regimes to ensure habitats remain suitable for their mammalian inhabitants. Captive breeding, translocation, and reintroduction aimed to bolster wild populations and are often supported by extensive research into the biology and ecology of the species to optimize their chances of survival.[8][9][10]
Given the dynamic nature of ecosystems and the ongoing challenges such as climate change, conservation strategies must be adaptable. This involves regularly assessing the effectiveness of conservation actions and being willing to modify approaches based on new scientific findings and changing environmental conditions. [10]
A mammal is a vertebrate animal of the class Mammalia. Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,400 extant species of mammals have been described and divided into 29 orders.
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a pouch. Living marsupials include kangaroos, koalas, opossums, Tasmanian devils, wombats, wallabies, and bandicoots among others, while many extinct species, such as the thylacine, Thylacoleo, and Diprotodon, are also known.
The platypus, sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypic taxon of its family Ornithorhynchidae and genus Ornithorhynchus, though a number of related species appear in the fossil record.
The fauna of Australia consists of a large variety of animals; some 46% of birds, 69% of mammals, 94% of amphibians, and 93% of reptiles that inhabit the continent are endemic to it. This high level of endemism can be attributed to the continent's long geographic isolation, tectonic stability, and the effects of a unique pattern of climate change on the soil and flora over geological time. A unique feature of Australia's fauna is the relative scarcity of native placental mammals. Consequently, the marsupials – a group of mammals that raise their young in a pouch, including the macropods, possums and dasyuromorphs – occupy many of the ecological niches placental animals occupy elsewhere in the world. Australia is home to two of the five known extant species of monotremes and has numerous venomous species, which include the platypus, spiders, scorpions, octopus, jellyfish, molluscs, stonefish, and stingrays. Uniquely, Australia has more venomous than non-venomous species of snakes.
Placental mammals are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished from monotremes and marsupials in that the fetus is carried in the uterus of its mother to a relatively late stage of development. The name is something of a misnomer considering that marsupials also nourish their fetuses via a placenta, though for a relatively briefer period, giving birth to less developed young which are then nurtured for a period inside the mother's pouch. Placentalia represents the only living group within Eutheria, which contains all mammals more closely related to placentals than to marsupials.
Echidnas, sometimes known as spiny anteaters, are quill-covered monotremes belonging to the family Tachyglossidae, living in Australia and New Guinea. The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the only surviving members of the order Monotremata. The diet of some species consists of ants and termites, but they are not closely related to the American true anteaters or to hedgehogs. Their young are called puggles.
Diprotodontia is the largest extant order of marsupials, with about 155 species, including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the hippopotamus-sized Diprotodon, and Thylacoleo, the so-called "marsupial lion".
Steropodon is a genus of prehistoric platypus-like monotreme, or egg-laying mammal. It contains a single species, Steropodon galmani, that lived about 105 to 93.3 million years ago (mya) during the Cretaceous period, from early to middle Cenomanian. It is one of the oldest monotremes discovered, and is one of the oldest Australian mammal discoveries.
Mammalia is a class of animal within the phylum Chordata. Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums. Many earlier ideas from Linnaeus et al. have been completely abandoned by modern taxonomists, among these are the idea that bats are related to birds or that humans represent a group outside of other living things. Competing ideas about the relationships of mammal orders do persist and are currently in development. Most significantly in recent years, cladistic thinking has led to an effort to ensure that all taxonomic designations represent monophyletic groups. The field has also seen a recent surge in interest and modification due to the results of molecular phylogenetics.
Tingamainus is a species of early placenta bearing mammal.
Handbook of the Mammals of the World (HMW) is a book series from the publisher Lynx Edicions. The nine volumes were published from 2009 to 2019. Each mammal family is assessed in a full text introduction with photographs and each species has a text account with a distribution map and illustrations on a plate. This is the second major project by Lynx Edicions since the release of the Handbook of the Birds of the World in 1992. The chief editors are Russell Mittermeier and Don E. Wilson in association with Conservation International, the Texas A&M University and the IUCN. Don E. Wilson is also editor of the reference work Mammal Species of the World.
Monotremes are mammals of the order Monotremata. They are the only known group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts, compared to the more common mammalian types. Although they are different from almost all mammals in that they lay eggs, like all mammals, the female monotremes nurse their young with milk.
Most mammals are viviparous, giving birth to live young. However, the five species of monotreme, the platypuses and the echidnas, lay eggs. The monotremes have a sex determination system different from that of most other mammals. In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian mammal.
Riversleigh fauna is the collective term for any species of animal identified in fossil sites located in the Riversleigh World Heritage Area.
1 2 3 Woodburne, M.O.; Case, J.A. (1996). "Dispersal, Vicariance, and the Late Cretaceous to Early Tertiary Land Mammal Biogeography from South America to Australia". Journal of Mammalian Evolution. 3 (2): 121–161. doi:10.1007/bf01454359. S2CID44211530.
1 2 Rose, Kenneth David (2006). "Reflections and Speculations on the Beginning of the Age of Mammals". The Beginning of the Age of mammals. Baltimore: The Johns Hopkins University Press. p.337. ISBN0-8018-8472-1. Archived from the original on February 22, 2013. Retrieved 2007-08-19.
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