widespread across the continent, which includes New Guinea. Its predecessor by some 4 to 6 million years was the considerably larger Thylacinus potens , whose fossil record is very meagre. The modern thylacine outlived both the marsupial lion, Thylacoleo carnifex , and the giant predatory kangaroo, Propleopus. It would also have competed to some extent with reptilian carnivores like the giant goanna and the terrestrial crocodile Quinkana . Even so, these represent a paucity of major predators, given the abundance and variety of herbivores. Down in size and occupying different niches are the Tasmanian devil, also once widespread on the mainland (and much larger than its modern-day descendant), and the tiger cats.
The Riversleigh fossil collections of Queensland provide a comprehensive thylacine picture back to a point: âFive species ranging in size from that of a big domestic cat to that of a dingo thrived 25 million years agoâa sure indication that they had been evolving for a long time. But by 15 million years ago they were reduced to two species, and by 8 million years ago there was only one.â 5
It is possible that the niche-specific thylacine developed relatively free of competition even from the much larger carnivorous megafauna, although rather than being an evolutionary bonus this may have spelled long-term problems once dingoes, men and dogs came on the scene. Although the theory of convergent evolution suggests that its canid-like features and some behavioural characteristics gave it a dominant position equivalent to that of the Northern Hemisphere wolf, some critical features may have been absent. 6 The thylacine may not have needed to develop genuine speed to go with its stamina when hunting wallaby and kangaroo. It may also have enjoyed the luxury of being able to depend exclusively upon these and similar prey, to the extent of feeding selectively from fresh kill. Perhaps it lacked the ability to scavenge and to learn to adopt an omnivorous diet in the face of later competition.
That the thylacine inhabited much of the Australian continent is further evidence of a lack of major competing predators; it also reveals an ability to adapt to dissimilar environments. This was particularly the case from about 6000 years ago when the interior began to dry out. There is no real evidence that thylacines were affected by the increasing aridity. On the contrary, Aboriginal rock and sacred cave art dating back to that time, in such areas as the Kimberley and Arnhem Land, vividly portrays the animal. There is also a famous mummified thylacine (see plate section), found in 1966 at the base of a shaft on the dry Nullarbor Plain, that fell in and died there about 4000 years ago. It would have lived in very different circumstances to the thylacines of Tasmania, by then separated from the mainland and affected in large areas by cold, moist Antarctic winds and cold ocean currents.
Predator follows prey (never the other way around!), and as the kangaroos and wallabies radiated into most parts of the continent, itâs entirely logical that the thylacine did likewise. Aborigines are known to have hunted them for food, but this would have been in a strictly utilitarian manner, in no way threatening the speciesâ existence. Ancient Aboriginal rock-cave art depicting thylacines exists in at least eight locations, scattered geographically and over time. There are about 30 known thylacine fossil sites, out of a total of about 70 significant Quaternary mammal sites in Australia. In an evolutionary sense, therefore, there is evidence that the thylacine evolved as a successful marsupial, unchallenged as the continentâs pre-eminent modern terrestrial carnivore.
3 AT THE END:
EXTINCTION
During our conversation, he told me that the last Tasmanian Tiger taken alive was caught at Adamsfield in the 1930s by his uncle. The method they used to trap the animal was to make a large box out of bush timber with a snare at the
The Riversleigh fossil collections of Queensland provide a comprehensive thylacine picture back to a point: âFive species ranging in size from that of a big domestic cat to that of a dingo thrived 25 million years agoâa sure indication that they had been evolving for a long time. But by 15 million years ago they were reduced to two species, and by 8 million years ago there was only one.â 5
It is possible that the niche-specific thylacine developed relatively free of competition even from the much larger carnivorous megafauna, although rather than being an evolutionary bonus this may have spelled long-term problems once dingoes, men and dogs came on the scene. Although the theory of convergent evolution suggests that its canid-like features and some behavioural characteristics gave it a dominant position equivalent to that of the Northern Hemisphere wolf, some critical features may have been absent. 6 The thylacine may not have needed to develop genuine speed to go with its stamina when hunting wallaby and kangaroo. It may also have enjoyed the luxury of being able to depend exclusively upon these and similar prey, to the extent of feeding selectively from fresh kill. Perhaps it lacked the ability to scavenge and to learn to adopt an omnivorous diet in the face of later competition.
That the thylacine inhabited much of the Australian continent is further evidence of a lack of major competing predators; it also reveals an ability to adapt to dissimilar environments. This was particularly the case from about 6000 years ago when the interior began to dry out. There is no real evidence that thylacines were affected by the increasing aridity. On the contrary, Aboriginal rock and sacred cave art dating back to that time, in such areas as the Kimberley and Arnhem Land, vividly portrays the animal. There is also a famous mummified thylacine (see plate section), found in 1966 at the base of a shaft on the dry Nullarbor Plain, that fell in and died there about 4000 years ago. It would have lived in very different circumstances to the thylacines of Tasmania, by then separated from the mainland and affected in large areas by cold, moist Antarctic winds and cold ocean currents.
Predator follows prey (never the other way around!), and as the kangaroos and wallabies radiated into most parts of the continent, itâs entirely logical that the thylacine did likewise. Aborigines are known to have hunted them for food, but this would have been in a strictly utilitarian manner, in no way threatening the speciesâ existence. Ancient Aboriginal rock-cave art depicting thylacines exists in at least eight locations, scattered geographically and over time. There are about 30 known thylacine fossil sites, out of a total of about 70 significant Quaternary mammal sites in Australia. In an evolutionary sense, therefore, there is evidence that the thylacine evolved as a successful marsupial, unchallenged as the continentâs pre-eminent modern terrestrial carnivore.
3 AT THE END:
EXTINCTION
During our conversation, he told me that the last Tasmanian Tiger taken alive was caught at Adamsfield in the 1930s by his uncle. The method they used to trap the animal was to make a large box out of bush timber with a snare at the
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