Australian megafauna were large animals that lived in Australia during the Pleistocene period. Many of these animals disappeared during the later part of the Pleistocene as part of a major extinction event that occurred worldwide. Scientists are still discussing whether human activity or changes in climate were the main reasons for their extinction.

Some of these ancient animals share similarities with mythical creatures described in Aboriginal Dreamtime stories.

Causes of extinction

Many modern scientists, including Tim Flannery, believe that the arrival of early Aboriginal Australians may have played a role in the extinction of large animals called megafauna. These early people may have hunted these animals and used fire to manage the land, which could have led to their disappearance. Some scientists also think that drier conditions during a time of heavy ice coverage (about 18,000 years ago) might have contributed, but most megafauna were already gone by this time. Others, like Steve Wroe, point out that there is not enough evidence to know exactly when many megafauna species died. Some species have no confirmed records from the last 100,000 years, and extinctions may have happened slowly over time due to climate changes before humans arrived.

New research using special dating methods shows that humans may have caused the extinction of some megafauna in Australia. These studies suggest that all large animals on the mainland disappeared around 46,000 years ago, which is when the first humans arrived. However, other studies later challenged these findings, noting that 50 out of 88 megafauna species had no evidence of living after about 130,000 years ago. Only 8–14 species were confirmed to have lived at the same time as humans. Analysis of tooth chemicals from megafauna suggests that the climate during their extinction was similar to today’s dry conditions, and these animals were adapted to such environments. Some scientists believe that humans caused sudden changes in plant life and animal diets by burning landscapes, which were not as fire-resistant as modern ones.

In Tasmania, evidence shows that Aboriginal people may have hunted megafauna to extinction around 41,000 years ago, after a land bridge connected the island to Australia. This happened without using fire, suggesting hunting was a key factor. Some studies suggest that changes in plant life were a result of megafauna disappearing, not the cause. Sediment samples from Lynch’s Crater in Queensland support this idea, showing that fires increased after megafauna vanished, leading to changes in plant types. However, the use of a fungus called Sporormiella as a sign of megafauna presence has been questioned, as it is also found in other animals and does not always reflect megafauna numbers.

A study of remains at Walker Creek in Queensland found that megafauna disappeared after a long period of environmental decline. Chemical analysis of eggshells from a flightless bird called Genyornis newtoni showed signs of burning, possibly from human fires. This was seen as direct evidence of humans causing extinction, but later studies argued the eggshells were from a smaller bird, not Genyornis. The timing of Genyornis’ extinction remains unclear.

Some scientists suggest that humans gradually caused megafauna to disappear, while others argue that these animals coexisted with humans for thousands of years. Debate continues about whether megafauna died before humans arrived. Tim Flannery, a scientist who wrote about human impact on ecosystems, has faced criticism for his conclusions. A 2021 study found that megafauna extinction rates varied, with some generalist species dying earlier and specialized ones later or even surviving today. Scientists propose that a mix of human and environmental factors caused these extinctions.

Living Australian megafauna

The term "megafauna" refers to large animals that weigh more than 100 kg (220 lb). In Australia, however, these animals were not as large as those on other continents. Because of this, scientists often use a less strict rule, defining megafauna as animals weighing more than 40 kg (88 lb).

Extinct Australian megafauna

The following is a list that is not complete of extinct Australian megafauna (monotremes, marsupials, birds, and reptiles) in the format:

Monotremes are listed from largest to smallest.

Marsupials are listed from largest to smallest.

Extinct megafauna contemporaneous with Aboriginal Australians

In Dreamtime stories, monsters and large animals are often linked to extinct megafauna. This connection was noted as early as 1845, when colonists recorded that Aboriginal people recognized Diprotodon bones as belonging to bunyips. Thomas Worsnop suggested that fears of bunyip attacks near water sources may have reflected a time when Diprotodon lived in wetlands.

In the early 1900s, John Walter Gregory described the Diyari people’s Kadimakara story, which describes Central Australia’s deserts as once being "fertile, well-watered plains" covered with giant gum trees and thick clouds. The trees formed a dense canopy where strange creatures called Kadimakara lived. These creatures sometimes came to the ground to eat. When the gum trees were destroyed, the Kadimakara were forced to stay on the ground, especially near Lake Eyre and Kalamurina, until they died.

During droughts or floods, the Diyari held ceremonies called corroborees, which included dances and rituals, at the bones of the Kadimakara. These ceremonies aimed to calm the creatures and ask them to help bring rain. Aboriginal people identified Kadimakara bones at sites that matched locations where megafauna fossils were found. An Aboriginal guide also recognized a Diprotodon jaw as belonging to the Kadimakara.

Gregory suggested the story might reflect a time when the Diyari lived elsewhere or when Central Australia’s environment was different. If the Diyari coexisted with megafauna, it would mean humans lived alongside these animals. Gregory wrote:

"If the geologist can determine whether the bones of the extinct monsters of Lake Eyre match those described in Aboriginal traditions, he can help solve several interesting problems. If the legends describe traits of the extinct animals that match their real features, the stories may show that humans lived in Central Australia at the same time as Diprotodon and giant kangaroos. If not, the traditions might reflect stories brought by people who moved to new areas."

— John Walter Gregory, Dead Heart of Australia

After studying fossils, Gregory concluded the Kadimakara story combined elements of real animals and environmental changes. He believed Lake Eyre’s environment had not changed much since Aboriginal people lived there. Some parts of the story likely described crocodiles that once lived in the lake, while others referred to Diprotodon, a large, heavy animal with a single horn on its forehead.

Geologist Michael Welland notes that Dreamtime stories across Australia describe giant creatures that lived in lush landscapes until droughts caused them to die in dry marshes like Kati Thanda–Lake Eyre. Examples include the Kadimakara of Lake Eyre and continent-wide tales of the Rainbow Serpent, which may relate to Wonambi naracoortensis, a large snake.

Journalist Peter Hancock suggests a Dreamtime story from Perth might describe Varanus priscus, a giant lizard that lived 46,000 years ago. However, the story mentions dingoes attacking this creature, even though dingoes arrived in Australia much later than the lizard’s extinction.

Rock art in the Kimberley region and Arnhem Land appears to show a marsupial lion and a marsupial tapir. Arnhem Land art also seems to depict Genyornis, a bird that went extinct about 40,000 years ago.

A fossil of an Early Triassic archosauromorph found in Queensland, named Kadimakara australiensis, is named after the Kadimakara.