Definitions

Australian_megafauna

Australian megafauna

Australian megafauna is a term used to describe a number of comparatively large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives. Many of these species became extinct during the Pleistocene (16,100±100 - 50,000 years before present).

The cause of the extinction is an active and contentious field of research. It is hypothesised that with the arrival of humans (around 48,000-60,000 years ago), hunting and the use of fire to manage their environment may have contributed to the extinction of the megafauna. Increased aridity during peak glaciation (about 18,000 years ago) may have also contributed to the extinction of the megafauna. Some proponents claim climate change alone caused extinction of the megafauna, but these arguments have to account for the fact that megaufaunal species comfortably survived two million years of climatic oscillations, including a number of arid glacial periods, before their sudden extinction.

New evidence based on accurate optically stimulated luminescence and Uranium-thorium dating of megafaunal remains suggests that humans were the ultimate cause of the extinction of megafauna in Australia. The dates derived show that all forms of megafauna became extinct in the same rapid timeframe — approximately 47,000 years ago — the period of time in which humans first arrived in Australia. The dates derived suggest the main mechanism for extinction was human burning of a then much less fire-adapted landscape; analysis of oxygen and carbon isotopes from teeth of megafauna indicate sudden, drastic, non-climate-related changes in vegetation and the diet of surviving marsupial species, as well as the loss of megafaunal species. Further analysis of oxygen and carbon isotopes from teeth of megafauna indicate the arid regional climates at the time of extinction were similar to arid regional climates of today, and that the megafauna were well adapted to arid climates.

Living Australian megafauna

Mammals

  • Red Kangaroo (Macropus rufus) This species is a very large kangaroo with short, red-brown fur, fading to pale buff below and on the limbs. It has long, pointed earlobes and a squared-off muzzle. Females are smaller than males and are blue-grey with a brown tinge, pale grey below, although arid zone females are coloured more like males. It has two appendages with small claws (much like arms), two muscular legs, which are used for jumping, and a tail, which is often used like a third leg for balance.

Red Kangaroos' legs work much like a rubber band. The male Red Kangaroo can leap in full force approximately 30 feet (9.14 m) in one leap. Males grows up to 1.8m (6ft) tall and weigh up to 85 kg (187lbs). Females grow up to 1.1m (3.6ft) tall and weigh up to 35kg (77lbs). Tails can be up to 1m (3ft) along.

Birds

  • Emu The emu was first described under the name of the New Holland Cassowary in Arthur Phillip's Voyage to Botany Bay, published in 1789.[4] The species was named by ornithologist John Latham, who collaborated on Phillip's book and provided the first descriptions of and names for many Australian bird species; its name is Latin for "fast-footed New Hollander". The etymology of the common name Emu is uncertain, but is thought to have come from an Arabic word for large bird that was later used by Portuguese explorers to describe the related Cassowary in New Guinea.[5] In Victoria, some terms for the emu were Barrimal in the Djadja wurrung language, myoure in Gunai, and courn in Jardwadjali.[6]

In his original 1816 description of the emu, Vieillot used two generic names; first Dromiceius, then Dromaius a few pages later. It has been a point of contention ever since which is correct; the latter is more correctly formed, but the convention in taxonomy is that the first name given stands, unless it is clearly a typographical error.[7] Most modern publications, including those of the Australian government,[8] use Dromaius, with Dromiceius mentioned as an alternative spelling.

  • Cassowary The Northern and Dwarf Cassowaries are not well known. All cassowaries are usually shy, secretive birds of the deep forest, adept at disappearing long before a human knows they are there. Even the more accessible Southern Cassowary of the far north Queensland rain forests is not well understood.

Reptiles

Being predatory lizards, goannas are often quite large, or at least bulky, with sharp teeth and claws. The largest is the Perentie (Varanus giganteus), which can grow over 2 m in length. They prey on all manner of small animals; insects, lizards, snakes, mammals, birds, eggs. Meals are often eaten whole, and thus the size of their meals depends on the size of the animal itself. However, the Perentie has been observed killing a young kangaroo, and then biting out chunks of flesh like a dog. Goannas have even been blamed for the death of sheep by farmers, though most likely erroneously, as goannas are also eaters of carrion and are attracted to rotting meat.

Not all goannas are gargantuan. Pygmy goannas may be smaller than a man's arm. The smallest of these, the short-tailed monitor (Varanus brevicuda) reaches only 20 cm in length. They survive on smaller prey such as insects and mice.

There are many further species in the carpet python complex, including the ochre-red Bredl's or Centralian python (Morelia bredli). This python, which is native to a small area around the MacDonnell Ranges and the town of Alice Springs in Australia's Northern Territory, is a unique member of the complex, having many more smaller scales, so that the body more closely resembles a skin. In captivity, striped, spotted and hypomelanistic specimens have been observed. Bredl's python is a medium sized carpet python, averaging around , however it is noted for its thicker girth. Adults can breed at a later age than most carpet pythons.

A healthy adult male saltwater crocodile is typically 4.8 to 7 metres (15.75 to 21.6 ft) long, and weighs up to 770 kg (1697 lb), with many exceptions being much larger than this. Many large sizes have been reported[1][2], [1] Females are much smaller than males, with typical female body lengths in the range of 2.5–3 meters. A 28 foot (8.5 m) individual was reportedly shot on the Norman River of Queensland in 1957 and a cast was made of this animal (which can be viewed and is quite the popular tourist attraction), but due to the time since the occurrence and lack of rock hard evidence (other than the plaster) it is not considered "official". The saltwater crocodile has fewer armor plates on its neck than other crocodilians, and its broad body contrasts with most other lean crocodiles, leading to early unverified assumptions the reptile was an alligator.[2]Crocodylus porosus (Schneider, 1801), by Adam Britton from the Crocodilian Species List.

Extinct Australian megafauna: pre-1788

The following is an incomplete list of Australian megafauna, in the format:

  • Latin name, (common name, period alive), and a brief description.

Mammals

Mammals are aranged by size with largest at the top.

1000-2000kilograms

  • Diprotodon optatum was the largest species of Diprotodontid. Approximately three metres long, two metres high at the shoulder and weighing up to two tonnes, it resembled a giant wombat. It is the largest marsupial currently known.
  • Diprotodon minor
  • Zygomaturus trilobus was a smaller (bullock-sized, about two metres long by one metre high) Diprotodontid that may have had a short trunk. It appears to have lived in wetlands, using two fork-like incisors to shovel up reeds and sedges for food.
  • Palorchestes azael (the Marsupial Tapir) was a Diprotodontid of a similar size to Zygomaturus, with long claws and a longish trunk. It lived in the Miocene.

100-1000 kilograms

  • Euwenia grata
  • Nototherium mitchelli
  • Euryzygoma dunense
  • Phascolonus gigas
  • Ramsayia magna
  • Procoptodon goliah (the Giant Short-faced Kangaroo) is the largest kangaroo to have ever lived. It grew 2-3 metres (7-10 feet) tall, and weighed up to 230 kilograms. It had a flat shortened face with jaw and teeth adapted for chewing tough semi-arid vegetation, and forward-looking eyes providing stereoscopic vision. Procoptodon was one of seventeen species in three genera in the Sthenurine subfamily, of whom all are extinct. Sthenurines inhabited open woodlands in central Northern Australia as the tropical rainforests were beginning to retreat. All sthenurines had an extremely developed, almost hoof-like, fourth toe on the hindlimbs, with other toes vestigial. Additionally, elastic ligaments between the toe bones gave this group improved spring and speed compared to modern kangaroos. Sthenurine forelimbs were long with two extra-long fingers and claws compared with the relatively small, stiff arms of modern macropods. These may have been used for pulling branches nearer for eating and for quadrupedal movement for short distances.
  • Protemnodon a form of giant wallaby with 4 species.
  • Procoptodon rapha, P. pusio and P. texasensis
  • Polorchestes parvus'
  • Macropus pearsoni and M. ferragus

10-100 kilograms

  • Simosthenurus pales
  • Sthenurus tindalei and S. atlas
  • Phascolarctos stirtoni was a koala similar to the modern form, but one third larger.
  • Phascolomys medius
  • Lasiorhinus angustioens
  • Congruus congruus a wallaby from Naracoorte.
  • Troposodon minor
  • Sthenurus oreas
  • Simosthenurus occidentalis (another Sthenurine) was about as tall as a modern Eastern Grey Kangaroo, but much more robust. It is one of the nine species of leaf-eating kangaroos identified in fossils found in the Naracoorte Caves National Park.
  • Simothenurus brownei
  • Propleopus oscillans (the Carnivorous Kangaroo), from the Miocene and Pliocene epochs, was a large (~70 kilogram) rat-kangaroo with large shearing and stout grinding teeth that indicate it may have been an opportunistic carnivore able to eat insects, vertebrates (possibly carrion), fruits, and soft leaves. Grew to about 1.5 - 3 metres in height.
  • Simothenurus maddocki
  • Sthenurus andersoni
  • Thylacoleo carnifex, (the Marsupial Lion), was the size of a leopard, and had a cat-like skull with large slicing pre-molars. It had a retractable thumb-claw and massive forelimbs. It was almost certainly carnivorous and a tree-dweller.
  • Vombatus hacketti
  • Macropus thor
  • Macropus piltonensis
  • Zaglossus hacketti was a sheep-sized echidna uncovered in Mammoth Cave in Western Australia, and is the largest monotreme so far uncovered.
  • Macropus rama
  • Simothenurus gilli
  • Warrendja wakefieldi a wombat from Naracoorte.
  • Zaglossis ramsayi
  • Sarcophilus harrisii laniarius was a large form of the Tasmanian Devil.
  • Megalibgwilia ramsayi was a large, long-beaked echidna with powerful forelimbs for digging. Its diet would probably have included worms and grubs rather than ants.

Birds

  • Family Dromornithidae: this group of birds was more closely related to waterfowl than modern ratites.
    • Dromornis stirtoni, (Stirton's Thunder Bird, Miocene epoch) was a flightless bird three metres tall that weighed about 500 kilograms. It is one of the largest birds so far discovered. It inhabited subtropical open woodlands and may have been carnivorous. It was heavier than the Moa and taller than the Aepyornis.
    • Bullockornis planei (the 'Demon Duck of Doom') was another huge member of the Dromornithidae. It was up to 2.5 metres tall and weighed up to 250 kilograms, and was probably carnivorous.
    • Genyornis newtoni (the Mihirung) was related to Dromornis, and was about the height of an ostrich. It was the last survivor of the Dromornithidae. It had a large lower jaw and was probably omnivorous.
  • Leipoa gallinacea (formerly Progura) was a giant malleefowl.

Reptiles

  • Varanus priscus (formerly Megalania prisca) was a giant, carnivorous goanna that might have grown to as long as seven metres, and weighed up to 1,940 kilograms (Molnar, 2004).
  • Wonambi naracoortensis was a non-venomous snake of five to six metres in length, an ambush predator at waterholes which killed its prey by constriction.
  • Quinkana sp., was a terrestrial crocodile which grew from five to possibly 7 metres in length. It had long legs positioned underneath its body, and chased down mammals, birds and other reptiles for food. Its teeth were blade-like for cutting rather than pointed for gripping as with water dwelling crocodiles. It belonged to the Mekosuchine subfamily (all now extinct). It was discovered at Bluff Downs in Queensland.
  • Liasis sp., (Bluff Downs Giant Python), lived during the Pliocene epoch, grew up to ten metres long, and is the largest Australian snake known. It hunted mammals, birds and reptiles in riparian woodlands. It is most similar to the extant Olive Python (Liasis olivacea).
  • Meiolania was a genus of huge terrestrial cryptodire turtle measuring 2.5 m (8 ft 4 inches) in length, with a horned head and spiked tail.

Extinctions (not megafauna) post 1788

Mythological Australian megafauna

References

  • Field, J. H. and J. Dodson. 1999. Late Pleistocene megafauna and archaeology from Cuddie Springs, south-eastern Australia. Proceedings of the Prehistoric Society 65: 1-27.
  • Field, J. H. and W. E. Boles. 1998. Genyornis newtoni and Dromaius novaehollandiae at 30,000 b.p. in central northern New South Wales. Alcheringa 22: 177-188.
  • Long, J.A., Archer, M. Flannery, T.F. & Hand, S. 2003. Prehistoric Mammals of Australia and New Guinea -100 Million Years of Evolution. Johns Hopkins University Press, Baltimore. 242pp.
  • Molnar, R. 2004. Dragons in the Dust: The Paleobiology of the Giant Lizard Megalania. Indiana University Press. Page: 127.
  • Murray, P. F. and D. Megirian. 1998. The skull of dromornithid birds: anatomical evidence for their relationship to Anseriformes (Dromornithidae, Anseriformes). Records of the South Australian Museum 31: 51-97.
  • Roberts, R. G., T. F. Flannery, L. A. Ayliffe, H. Yoshida, J. M. Olley, G. J. Prideaux, G. M. Laslett, A. Baynes, M. A. Smith, R. Jones, and B. L. Smith. 2001. New ages for the last Australian megafauna: continent-wide extinction about 46,000 years ago. Science 292: 1888-1892.
  • Wroe, S., J. Field, and R. Fullagar. 2002. Lost giants. Nature Australia 27(5): 54-61.
  • Gavin J Prideaux, Richard G. Roberts, Dirk Megirian, Kira E. Westaway, John C. Hellstrom, John M. Olley. 2007. Mammalian responses to Pleistocene climate change in southeastern Australia. Geology, v. 35, n. 1, p. 33-36.

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