Australia: The Land Where Time Began

Thylacoleonidae - Marsupial Lions

Prior to the discovery of the Riversleigh deposits, the only well-known marsupial lion was from the Pleistocene, Thylacoleo carnifex, about the size of a modern leopard and distantly related to wombats. The mass of T. carnifex has been revised up to at least 100 kg (Wroe et al., 2003).

After some discussion about their diet, is has been agreed that they ate meat and probably bones. A study compared them to carnivores from around the world and the conclusion was that it was the most highly specialised mammalian meat-eater known to have evolved in the world, based on its huge, sectorial shearing premolar. Biomechanical studies of a model of the jaws of a small Thylacoleo, about half the size of a lioness, found that it produced almost as much biting power as an adult lioness, making it probably the most powerful bite for its size of any known mammalian carnivore. Experiments with a sheep's head (not a living sheep) found that although the incisors appeared more chisel-like than other predators, they actually pushed the neck of the sheep back between the highly specialised shearing premolars. It also had powerful retractable claws, especially on the thumbs, that were very large and powerful. There is disagreement as to how it used these fearsome thumb weapons, some favouring the suggestion that they were used for slashing the prey, others preferring the suggestion that they were used like grappling hooks, firmly locking on to the prey. They appear to have looked similar to a stretched out wombat, to which they are related, but they were no cuddly fur ball. To the first Aboriginal People, who almost certainly encountered them when they arrived in Australia, they must have been a very dangerous animal.

Among the species known from non-Riversleigh sites are Preisileo pitikantensis, a cat-sized species from the Late Oligocene, dog sized species of Wakaleo from the Early Miocene, Wakaleo oldfieldi, and from the Middle Miocene, Wakaleo vanderleuri, and from the Late Miocene, Wakaleo alcootaensis. Some small-dog sized species of Thylacoleo are known from the Late Miocene, Thylacoleo hilli, and the leopard-sized Thylacoleo crassidentatus from the Pliocene. A complete skull of Wakaleo vanderleueri has been found in the Middle Miocene deposits at Bullock Creek in the Northern Territory.

Thylacoleo carnifex–Predatory Behaviour as Revealed by Morphology of Elbow Joint – Ecomorphological Determinations in Absence of Living Analogues⁴

Thylacoleo carnifex (“pouched lion”) (Mammalia: Marsupialia: Diprotodontia: Thylacoleonidae), was a carnivorous marsupial in Australia during Pleistocene. Though it is generally agreed that T. carnifex had a hypercarnivorous diet, it has remained uncertain how it killed its prey. In this paper Figueirido et al. present their findings based on the use of geometric morphometrics regarding the shape of the elbow joint (the anterior articular surface of the distal humerus) in a wide sample of extant mammals for which their behaviour is known to determine how forearm use is reflected in the anatomy of the elbow. This information was used to investigate the predatory behaviour of Thylacoleo. It was indicated by a principal components analysis that Thylacoleo is the only known carnivorous mammal that clusters with extant taxa in which the degree of forearm manoeuvrability is extreme, such as primates and arboreal xenarthrans (pilosans). Thylacoleo was confirmed by canonical variates analysis to have forearm manoeuvrability that was intermediate between wombats (terrestrial) and arboreal mammals and a much greater degree of manoeuvrability than living carnivoran placentals. It was shown by a linear discriminant analysis computed to separate the morphology of the elbow of arboreal mammals from terrestrial mammals that Thylacoleo was primarily terrestrial but with some climbing abilities. Figueirido et al. inferred from their results that Thylacoleo used its forearms for grasping or manipulating prey to a much higher degree than its supposed extant placental counterpart, the African lion (Panthera leo). In the light of this new information Figueirido et al. discuss the use of the large, retractable claw on the semiopposable thumb by Thylacoleo for potentially slashing and disemboweling prey.

Priscileo
P. pitikantensis - Upper Oligocene
P. roskellyae - Middle Miocene
Subfamily Wakaleoninae
Wakaleo alcootaensis - Upper Miocene
W. oldfieldi - Lower - Upper Miocene
W. vanderleueri - Middle-Upper Miocene
Subfamily Thylacoleoninae
Thylacoleo carnifex - Pleistocene
T. crassidentatus - Pliocene
T. hilli - Pliocene

Depicted in Rock Art

In his book, Australian Mammal Extinctions, Chris Johnson refers to many paintings in Arnhem Land of animals that look very much like thylacines, and among them are some that are slightly different, with no stripes and a tufted tail, tail butts clearly demarcated from the body, with broad paws and limb proportions that are very similar to those of the marsupial lion. According to Murray & Chaloupka, the painting of one of these animals appears to be dead. They suggest it appears as though a dead animal may have been laid out for the artist.

Wikipedia

See Riversleigh Marsupial Lions

Links

Climate Change, Not Human Activity, Led to Megafauna Extinction

Sources & Further reading

Michael Archer, Suzanne J. Hand & Henk Godthelp, Australia's Lost World: Riversleigh, world heritage Site, Reed New Holland
Chris Johnson, Australia's Mammal Extinctions, a 50,000 year history, Cambridge University Press, 2006
Josephine Flood, Archaeology of the Dreamtime, JB Publications, 2004
Figueirido, B., A. Martín-Serra and C. M. Janis (2016). "Ecomorphological determinations in the absence of living analogues: the predatory behavior of the marsupial lion (Thylacoleo carnifex) as revealed by elbow joint morphology." Paleobiology 42(3): 508-531.