Marsupial Lion
Encyclopedia
The Marsupial Lion is an extinct species of carnivorous marsupial
mammal that lived in Australia
from the early to the late Pleistocene
(1,600,000–46,000 years ago). Despite its name it is not closely related to the lion
, but is a member of the order
Diprotodontia
.
The Marsupial Lion is the largest meat-eating mammal
known to have ever existed in Australia, and one of the largest marsupial carnivores from anywhere in the world (although see Thylacosmilus
and Borhyaena
). Individuals ranged up to around 75 cm (29.5 in) high at the shoulder and about 150 cm (60 in) from head to tail. Measurements taken from a number of specimens show that they averaged 100 to 130 kg (220 to 285 lb) in weight although individuals heavier than 160 kg (350 lb) may not have been uncommon. This would make it quite comparable to female lions and tiger
s in general size.
The animal was extremely robust with powerfully built jaws and very strong forelimbs. It possessed retractable claws, a unique trait among marsupials. This would have allowed the claws to remain sharp by protecting them from being worn down on hard surfaces. The claws were well-suited to securing prey and for climbing trees. The first digits ("thumbs") on each hand were semi-opposable and bore an enlarged claw. Palaeontologists believe that this would have been used to grapple with and slash at its intended prey as well as providing it with a sure footing on tree trunks and branches. The hind feet had four functional toes, the first digit being much reduced in size but possessing a roughened pad similar to that of possum
s, which may have assisted with climbing. It is unclear whether the Marsupial Lion exhibited syndactyly
(fused second and third toes) like other diprotodonts.
The Marsupial Lion's hindquarters were also well-developed although to a lesser extent than the front of the animal. Remains of the animal show that it had a relatively thick and strong tail and that the vertebrae possessed chevrons on their undersides where the tail would have contacted the ground. These would have served to protect critical elements such as nerves and blood vessels if the animal used its tail to support itself when on its hind legs, much like present day kangaroos
do. Taking this stance would free up its forelimbs to tackle or slash at its intended victim.
s on both the upper (maxilla
e) and lower (mandible
s) jaws. However, these teeth (the lower in particular) were shaped much more like the pointed canine
teeth of animals such as dog
s and cat
s than those of Kangaroos. It is not known whether the incisors would have been used to simply stab at and pierce the flesh of its prey or whether they had more specialised functions such as separating neck vertebrae, severing the spinal cord
, or lacerating major blood vessel
s such as the carotid artery
or jugular vein
s.
However, the most unusual feature of the creature's dentition were the huge blade-like carnassial
premolar
s on either side of its jaws. The top and bottom carnassials worked together like shears
and would have been very effective at slicing off chunks of flesh from carcasses
and cutting through bone.
The jaw muscle
of the Marsupial Lion was exceptionally large for its size, giving it an extremely powerful bite. Biometric calculations show that, pound for pound, it had the strongest bite of any known mammal, living or extinct – a 100 kg (220 lb) individual would have had a bite comparable with that of a 250 kg (550 lb) African Lion.
, either sneaking up and then leaping upon its prey, or dropping down on it from overhanging tree branches. It is thought to have hunted large animals such as the Hippopotamus
-sized Diprotodon
and giant browsing
kangaroo
s like Sthenurus
and Procoptodon
. Despite its size it may not have been a true apex predator
as it shared at least part of its range with the 6 metre (20 ft) long goanna
Megalania
. The Marsupial Lion may have cached kills in trees in a manner similar to the modern Leopard
. Like many predators, it was probably also an opportunistic scavenger
, feeding off carrion
and driving off less powerful predators from their kills.
CT
scans of a well-preserved skull
have allowed scientists to study internal structures and create a brain endocast
showing the surface features of the animal's brain. The parietal lobe
s, visual cortex
, and olfactory bulb
s of the cerebrum were enlarged indicating that the Marsupial Lion had a good sense of hearing, sight, and smell, as might be expected of an active predator. There were also a pair of blind canals within the nasal cavity
which were probably associated with detecting pheromone
s as in the Tasmanian Devil
. This indicates that it most likely had seasonal mating
habits and would "sniff out" a mate when in season.
n continent
. A large proportion of its environment would have been similar to the southern third of Australia today - semi-arid
open scrub and woodland
punctuated by waterhole
s and water courses.
It would have co-existed with many of the so-called Australian megafauna
such as the previously mentioned Diprotodon, giant kangaroos, and Megalania, as well as giant wallabies
like Protemnodon
, the giant wombat
Phascolonus
, and the thunderbird
Genyornis
.
Many of these animals would have been prey for adult Marsupial Lions. The Marsupial Lion was especially adapted
for hunting large animals but was not particularly suited to catching smaller prey. The relatively quick reduction in the numbers of its primary food source around 40,000 to 50,000 years ago probably led to the decline and eventual extinction of the Marsupial Lion. There now appears to be little doubt that these events were precipitated by the arrival of human
s in Australia and the use of fire-stick farming
.
s, and the koala
. It is further classified in its own family
, the Thylacoleonidae
, of which 3 genera
and 11 species
are recognised, all extinct. The term marsupial lion (lower case) is often applied to other members of this family. The Marsupial Lion's closest living relatives are the herbivorous Koala and wombat
s.
Fossil
s of the Marsupial Lion have been found at a number of sites in Australia since the mid-19th century. However, it was only recently that a complete articulated skeleton was discovered in limestone
caves under the Nullarbor Plain
in 2002. The ends of the limb bones were not fully fused indicating that the animal was a sub-adult and not fully-grown.
Unlike most fossils, these bones were not mineralised and had been preserved in this state for approximately 500,000 years by the low humidity
and cool temperature of the cave. The partial remains of ten other individuals were found in this or nearby caves, along with hundreds of other specimens of other animals.
It is believed the animals fell to their death tens of metres below, through narrow openings in the roof of the caves known as sinkhole
s. The caves and sinkholes were formed by groundwater slowly dissolving and eroding the limestone forming the bed of the plain (once a shallow sea).
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
mammal that lived in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
from the early to the late Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
(1,600,000–46,000 years ago). Despite its name it is not closely related to the lion
Lion
The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...
, but is a member of the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Diprotodontia
Diprotodontia
Diprotodontia is a large order of about 120 marsupial mammals including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the rhinoceros-sized Diprotodon, and Thylacoleo, the so-called "marsupial lion"....
.
Description
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
known to have ever existed in Australia, and one of the largest marsupial carnivores from anywhere in the world (although see Thylacosmilus
Thylacosmilus
Thylacosmilus was a genus of sabre-toothed metatherian predators that first appeared during the Miocene. Remains of the animal have been found in parts of South America, primarily Argentina...
and Borhyaena
Borhyaena
Borhyaena is an extinct genus of South American metatherian, living between 20 and 15 million years ago.Borhyaena was a large, bear-like marsupial predator of up to long and with an estimated average weight of . A typical borhyaenid, it had flat feet and a heavy build...
). Individuals ranged up to around 75 cm (29.5 in) high at the shoulder and about 150 cm (60 in) from head to tail. Measurements taken from a number of specimens show that they averaged 100 to 130 kg (220 to 285 lb) in weight although individuals heavier than 160 kg (350 lb) may not have been uncommon. This would make it quite comparable to female lions and tiger
Tiger
The tiger is the largest cat species, reaching a total body length of up to and weighing up to . Their most recognizable feature is a pattern of dark vertical stripes on reddish-orange fur with lighter underparts...
s in general size.
The animal was extremely robust with powerfully built jaws and very strong forelimbs. It possessed retractable claws, a unique trait among marsupials. This would have allowed the claws to remain sharp by protecting them from being worn down on hard surfaces. The claws were well-suited to securing prey and for climbing trees. The first digits ("thumbs") on each hand were semi-opposable and bore an enlarged claw. Palaeontologists believe that this would have been used to grapple with and slash at its intended prey as well as providing it with a sure footing on tree trunks and branches. The hind feet had four functional toes, the first digit being much reduced in size but possessing a roughened pad similar to that of possum
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...
s, which may have assisted with climbing. It is unclear whether the Marsupial Lion exhibited syndactyly
Syndactyly
Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
(fused second and third toes) like other diprotodonts.
The Marsupial Lion's hindquarters were also well-developed although to a lesser extent than the front of the animal. Remains of the animal show that it had a relatively thick and strong tail and that the vertebrae possessed chevrons on their undersides where the tail would have contacted the ground. These would have served to protect critical elements such as nerves and blood vessels if the animal used its tail to support itself when on its hind legs, much like present day kangaroos
KangaROOS
KangaROOS are an American brand of sneaker originally produced from 1979 through the 1980s, with a later revival that continues in present. They were notable for having a small zippered pocket on the side of the shoe, large enough for a small amount of loose change, keys, or more recently,...
do. Taking this stance would free up its forelimbs to tackle or slash at its intended victim.
Dentition
The Marsupial Lion was a highly specialised carnivore and this is reflected in its dentition (teeth). Like other diprotodonts, it possessed enlarged incisorIncisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s on both the upper (maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
e) and lower (mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
s) jaws. However, these teeth (the lower in particular) were shaped much more like the pointed canine
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
teeth of animals such as dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s and cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s than those of Kangaroos. It is not known whether the incisors would have been used to simply stab at and pierce the flesh of its prey or whether they had more specialised functions such as separating neck vertebrae, severing the spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
, or lacerating major blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s such as the carotid artery
Carotid artery
Carotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
or jugular vein
Jugular vein
The jugular veins are veins that bring deoxygenated blood from the head back to the heart via the superior vena cava.-Internal and external:There are two sets of jugular veins: external and internal....
s.
However, the most unusual feature of the creature's dentition were the huge blade-like carnassial
Carnassial
Carnassials are large teeth found in many carnivorous mammals, used for shearing flesh and bone in a scissor- or shear-like way. In the Carnivora, the carnassials are the modified last upper premolar and the first molar, but in the prehistoric creodonts, the carnassials were further back in the...
premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
s on either side of its jaws. The top and bottom carnassials worked together like shears
Scissors
Scissors are hand-operated cutting instruments. They consist of a pair of metal blades pivoted so that the sharpened edges slide against each other when the handles opposite to the pivot are closed. Scissors are used for cutting various thin materials, such as paper, cardboard, metal foil, thin...
and would have been very effective at slicing off chunks of flesh from carcasses
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
and cutting through bone.
The jaw muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
of the Marsupial Lion was exceptionally large for its size, giving it an extremely powerful bite. Biometric calculations show that, pound for pound, it had the strongest bite of any known mammal, living or extinct – a 100 kg (220 lb) individual would have had a bite comparable with that of a 250 kg (550 lb) African Lion.
Behaviour
The Marsupial Lion's limb proportions and muscle mass distribution indicate that, although it was a powerful animal, it was not a particularly fast runner. Palaeontologists conjecture that it was an ambush predatorAmbush predator
Ambush predators or sit-and-wait predators are carnivorous animals that capture prey by stealth or cunning, not by speed or necessarily by strength. These organisms usually hide motionless and wait for prey to come within striking distance. They are often camouflaged, and may be solitary...
, either sneaking up and then leaping upon its prey, or dropping down on it from overhanging tree branches. It is thought to have hunted large animals such as the Hippopotamus
Hippopotamus
The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest...
-sized Diprotodon
Diprotodon
Diprotodon, meaning "two forward teeth", sometimes known as the Giant Wombat or the Rhinoceros Wombat, was the largest known marsupial that ever lived...
and giant browsing
Browsing (predation)
Browsing is a type of herbivory in which an herbivore feeds on leaves, soft shoots, or fruits of high growing, generally woody, plants such as shrubs. This is contrasted with grazing, usually associated with animals feeding on grass or other low vegetation...
kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s like Sthenurus
Sthenurus
Sthenurus is an extinct genus of kangaroo. With a length of about 3 m , some species were twice as large as modern extant species. Sthenurus was related to the better-known Procoptodon.-Fossil habitats:...
and Procoptodon
Procoptodon
Procoptodon was a genus of giant short-faced kangaroo living in Australia during the Pleistocene epoch. P. goliah, the largest known kangaroo that ever existed, stood approximately 2 meters tall. They weighed about ....
. Despite its size it may not have been a true apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
as it shared at least part of its range with the 6 metre (20 ft) long goanna
Goanna
Goanna is the name used to refer to any number of Australian monitor lizards of the genus Varanus, as well as to certain species from Southeast Asia.There are around 30 species of goanna, 25 of which are found in Australia...
Megalania
Megalania
Megalania is a giant extinct goanna or monitor lizard. It was part of a megafaunal assemblage that inhabited southern Australia during the Pleistocene, and appears to have disappeared around 40,000 years ago...
. The Marsupial Lion may have cached kills in trees in a manner similar to the modern Leopard
Leopard
The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...
. Like many predators, it was probably also an opportunistic scavenger
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
, feeding off carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
and driving off less powerful predators from their kills.
CT
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
scans of a well-preserved skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
have allowed scientists to study internal structures and create a brain endocast
Endocast
An endocast is the internal cast of a hollow object, often specifically used for an endocasts of the cranial vault. Endocasts can be man-made for examining the properties of a hollow, inaccessible space, or occur naturally through fossilisation....
showing the surface features of the animal's brain. The parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
s, visual cortex
Visual cortex
The visual cortex of the brain is the part of the cerebral cortex responsible for processing visual information. It is located in the occipital lobe, in the back of the brain....
, and olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
s of the cerebrum were enlarged indicating that the Marsupial Lion had a good sense of hearing, sight, and smell, as might be expected of an active predator. There were also a pair of blind canals within the nasal cavity
Nasal cavity
The nasal cavity is a large air filled space above and behind the nose in the middle of the face.- Function :The nasal cavity conditions the air to be received by the other areas of the respiratory tract...
which were probably associated with detecting pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
s as in the Tasmanian Devil
Tasmanian Devil
The Tasmanian devil is a carnivorous marsupial of the family Dasyuridae, now found in the wild only on the Australian island state of Tasmania. The size of a small dog, it became the largest carnivorous marsupial in the world following the extinction of the thylacine in 1936...
. This indicates that it most likely had seasonal mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
habits and would "sniff out" a mate when in season.
Palaeoecology
Numerous fossil discoveries indicate that the Marsupial Lion was distributed across much of the AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n continent
Continent
A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
. A large proportion of its environment would have been similar to the southern third of Australia today - semi-arid
Semi-arid
A semi-arid climate or steppe climate describes climatic regions that receive precipitation below potential evapotranspiration, but not extremely...
open scrub and woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...
punctuated by waterhole
Depression (geology)
A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...
s and water courses.
It would have co-existed with many of the so-called Australian megafauna
Australian megafauna
Australian megafauna are a number of 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...
such as the previously mentioned Diprotodon, giant kangaroos, and Megalania, as well as giant wallabies
Wallaby
A wallaby is any of about thirty species of macropod . It is an informal designation generally used for any macropod that is smaller than a kangaroo or wallaroo that has not been given some other name.-Overview:...
like Protemnodon
Protemnodon
Protemnodon is a genus of megafaunal macropods that existed in Australia, Tasmania and Papua New Guinea in the Pleistocene. Based on fossil evidence it is thought that Protemnodon was physically similar to wallabies but far larger; Protemnodon hopei was the smallest in the genus weighing about 45...
, the giant wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
Phascolonus
Phascolonus
Phascolonus was a genus of prehistoric Australian marsupial in the wombat family. The largest species, Phascolonus gigas weighed as much as 200 kg. Phascolonus existed alongside with an even larger marsupial, Diprotodon, which weighed as much as two tons and was distantly related to wombats...
, and the thunderbird
Dromornithidae
Dromornithidae — the dromornithids — were a family of large, flightless Australian birds of the Oligocene through Pleistocene epochs. All are now extinct. They were long classified in the order Struthioniformes, but are now usually classified as a family of Anseriformes1...
Genyornis
Genyornis
Genyornis was a monotypic genus of large, flightless bird that lived in Australia until 50±5 thousand years ago. Many species became extinct in Australia around that time, coinciding with the arrival of humans....
.
Many of these animals would have been prey for adult Marsupial Lions. The Marsupial Lion was especially adapted
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
for hunting large animals but was not particularly suited to catching smaller prey. The relatively quick reduction in the numbers of its primary food source around 40,000 to 50,000 years ago probably led to the decline and eventual extinction of the Marsupial Lion. There now appears to be little doubt that these events were precipitated by the arrival of human
Human
Humans are the only living species in the Homo genus...
s in Australia and the use of fire-stick farming
Fire-stick farming
Fire-stick farming is a term coined by Australian archaeologist Rhys Jones in 1969 to describe the practice of Indigenous Australians where fire was used regularly to burn vegetation to facilitate hunting and to change the composition of plant and animal species in an area.Fire-stick farming had...
.
Classification
The Marsupial Lion is classified in the order Diprotodontia along with many other well-known marsupials such as kangaroos, possumPossum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...
s, and the koala
Koala
The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....
. It is further classified in its own family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, the Thylacoleonidae
Thylacoleonidae
Thylacoleonidae is a family of extinct meat-eating marsupials from Australia, referred to as marsupial lions. The best known is Thylacoleo carnifex, also called the Marsupial Lion...
, of which 3 genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
and 11 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are recognised, all extinct. The term marsupial lion (lower case) is often applied to other members of this family. The Marsupial Lion's closest living relatives are the herbivorous Koala and wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
s.
Fossils
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of the Marsupial Lion have been found at a number of sites in Australia since the mid-19th century. However, it was only recently that a complete articulated skeleton was discovered in limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
caves under the Nullarbor Plain
Nullarbor Plain
The Nullarbor Plain is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its north. It is the world's largest single piece of limestone, and occupies an area of about...
in 2002. The ends of the limb bones were not fully fused indicating that the animal was a sub-adult and not fully-grown.
Unlike most fossils, these bones were not mineralised and had been preserved in this state for approximately 500,000 years by the low humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
and cool temperature of the cave. The partial remains of ten other individuals were found in this or nearby caves, along with hundreds of other specimens of other animals.
It is believed the animals fell to their death tens of metres below, through narrow openings in the roof of the caves known as sinkhole
Sinkhole
A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...
s. The caves and sinkholes were formed by groundwater slowly dissolving and eroding the limestone forming the bed of the plain (once a shallow sea).
See also
- Australian megafaunaAustralian megafaunaAustralian megafauna are a number of 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...
- Pleistocene megafaunaPleistocene megafaunaPleistocene megafauna is the set of species of large animals — mammals, birds and reptiles — that lived on Earth during the Pleistocene epoch and became extinct in a Quaternary extinction event. These species appear to have died off as humans expanded out of Africa and southern Asia,...