Why does australia have mostly marsupials

Some form of primitive hopping locomotion by kangaroo ancestors is probably quite old, perhaps dating back to the Eocene based on inferences from molecular dates, not fossils. However, fast bipedal hopping is only an effective means of locomotion in deserts, grasslands and other open habitats free of overhanging woody vegetation , which became widespread in Australia much later, in the last 15 million years or so. Hopping is similar to galloping in that energy is stored in elastic tendons between strides, so these gaits might be energetically equivalent solutions for fast or long-distance locomotion.

Australian marsupials evolved in many ways to meet the challenges of drier habitats over the last 15 million years. Teeth, for example, reflect adaptive changes from browsing on woody vegetation in moist climates to grazing on grasses in arid climates. Kangaroo ancestors were quadrupedal walking on four legs most of the time in forested habitats and became progressively more bipedal as habitats dried out and opened up.

Well, I must confess a fondness for opossums New World marsupials , so much less charismatic than kangaroos and koalas, but with their own unique adaptations. Several opossum species, for example, eat venomous snakes. Snake-venom resistance is a biochemical, not a morphological adaptation, and it is another example of convergent evolution: besides opossums, mongooses and hedgehogs are also snake-venom resistant. The end of the wet season heralds the arrival of Black Wallaroo joeys , with families taking shelter in the picturesque rocky escarpments.

It is the smallest of the Wallaroos as well as the most distinctive, with its striking black silhouette. Antilopine Wallaroos are more commonly seen in larger mobs in the Savanna woodlands, with breeding reaching a peak at this time. Dingos sightings are more prevalent across Kakadu and Arnhem Land after the wet season, where they commonly prey on Agile Wallabies and other small mammals.

Northern Quolls typically breed from mid-May onwards, where incredibly males die shortly after mating from exhaustion, leaving the females to raise the young alone. Numbers are increasing in the area due to a reintroduction program, however, the species has been significantly effected by preying on the poisonous introduced Cane Toad.

The pretty Agile Wallaby is the most abundant macropod in the tropics, with its range growing across the floodplains and creek beds at this time due to the lower availability of food and fresh water.

Dingos can also be heard howling into the evening, with young males often solitary and nomadic versus breeding adults that often form a settled pack. Black Wallaroos are seen across the rocky habitats whilst their cousin, the Antilopine Wallaroo sticks to more heavily timbered regions in the Savanna. Colonies of Ghost Bats with their large protruding ears can be seen around caves and rocky outcrops situated in Arnhemland, whilst the Black Flying Fox, Little Red Flying Fox and Blossom Bat congregate in large groups following the ripening of fruit and the blossoming pollens of eucalypts, melaleuca paperbarks and banksias.

As water dries up, the concentration of Agile Wallabies around creeks and billabongs increases significantly, putting them at greater risk of being ambushed by Saltwater Crocodiles and Dingoes. This common macropod of the area typically feeds on leaf matter, roots and buds of burnt speargrasses over these months, as they wait for the wet season to begin.

A highlight for visitors is seeing males fighting as box using their paws and legs, balancing on their tails. A number of nocturnal animals can be seen at dusk at this time including the Northern Brown Bandicoot, Brush-tailed Phascogale and Northern Quoll. The Northern Quoll feeds primarily on invertebrates, but also consumes fleshy fruit, small mammals, birds, lizards, snakes, and frogs.

Long-nosed Potoroos and Tasmanian Bettongs have no specific breeding season, with animals capable of giving birth throughout the year, although there is a skew of young being born at the end of winter to early spring. The Tasmanian Bettong is only found in the eastern half of Tasmania and can be seen across the dry open eucalypt forests and grassy woodlands in late afternoons and early evening, being largely nocturnal.

Common Wombats are also abundant at this time. The Long-nosed Potoroo feeds upon seeds, roots, bulbs, insects, but prefers underground fungi which is dug up using their strong forepaws. Tasmanian Devils usually breed in March, with their young born in April after a 21 day gestation.

Common Brushtail and Ringtail Possums also typically give birth from April onwards, with a couple of young remaining in the pouch for about four months. This time of year also provides opportunities to see Short-beaked Echidnas before they enter periods of hibernation and Common Wombats , that are abundant at various national parks including Narawntapu and Cradle Mountain.

Eastern-barred and Southern-brown Bandicoots young are born between late May and December, with females having the ability to produce litters of up to four young. Breeding also occurs in early winter for Eastern and Spotted-tail Quolls with females giving birth to up to 30 young, however, with only six teats, there is a high mortality rate. Tasmanian Devils start to emerge from their dens towards the latter part of winter, with imps baby devils often seen on their backs.

The summer months are a peak time to see young carnivorous marsupials including Tasmanian Devils, Spotted-tailed and Eastern Quolls. Quolls are largely solitary animals and scavenge on insects and small mammals such as rabbits, mice and rats. They are found around various habitats, especially around Mt Field National Park. Common Wombats avoid the heat of the day, coming out to graze in the mornings and afternoons when temperatures are lower.

Although the wombat may breed at any time of the year, mating most often occurs during winter, so at this time, baby wombats can be seen in tow with their mothers. The Common Wombat is a resident of the lush East Gippsland forests. Known for their remarkable digging and excavation prowess, they have very specific requirements before they come out of their underground burrows, with the temperature above ground required to be lower than 20 degrees Celsius.

Cool nights in Spring are the best times to see them. These ancient marsupials appeared to flourish in North America, populating what was then the supercontinent Laurasia with about 15 to 20 different marsupial species, all of which are now extinct, Beck said.

It's unclear why these marsupials did well. But for some reason, at about the time that the nonavian dinosaurs went extinct, about 66 million years ago, the marsupials made their way down to South America.

At that time, North and South America weren't connected as they are today. But the two continents were very close, and a land bridge or a series of islands may have linked them. This connection allowed all kinds of animals to expand their stomping grounds. Once in South America, marsupials and their close relatives had a field day, diversifying like crazy within 2 million to 3 million years after arriving, Beck said. For instance, marsupials and their close relatives evolved into bear- and weasel-size carnivores, and one even evolved saber teeth.

Others evolved to eat fruits and seeds. Many of these marsupials went extinct between then and now, but South America is still a marsupial hotspot today. There are more than species of opossums, seven species of shrew opossums and the adorable monito del monte Dromiciops gliroides , whose Spanish name translates to "little monkey of the mountain.

On a side note, within the last 1 million years, one of South America's opossums traveled north and now lives in North America. The toes of many marsupials appear conjoined with webbing, a mutation known as syndactyly.

The koala is a perfect example. The Australian Museum respects and acknowledges the Gadigal people as the First Peoples and Traditional Custodians of the land and waterways on which the Museum stands. Image credit: gadigal yilimung shield made by Uncle Charles Chicka Madden. This website uses cookies to ensure you get the best experience on our website.