People ask why there are no big cats in Australia but they could also ask a much wider question namely, “Why are there no native cats at all in Australia?”
The answer must be found in the fact that the evolution of the island continent of Australia and the evolution of cats as a species, and big cats in particular, were out of synchronisation with each other.
My understanding of the evolution of the island of Australia (it has to be described as an island even though it is also a continent) is that it split off from Antarctica and travelled north, and is still doing so at about 7 cm annually, about 55 million years ago.
About 40 million years ago the first early examples of cats evolved on the planet. The big cats, to the best of my knowledge, evolved around 2.5 million years ago depending upon the species. Fossils of jaguars dated to 2.5 million years ago have been found. Fossils of lions have been found which were dated to a similar age. The fossil history of the tiger goes back approximately 1.5 million years.
So let’s say that the big cats began to evolve as separate species around 3 million years ago. At that time Australia was an island. The lion evolved in Africa on the African continent. The tiger apparently originates from Siberia and migrated south to Asia. It could not migrate further south to Australia because there was a water mass between Asia and Australia by that time. The jaguar evolved in South America as it is described now. Once again by the time the animal had evolved it could not migrate to Australia. The leopard’s natural domain is far north of Australia.
If, on the other hand early cat species had made their home in what is now Australia before the continent of Australia drifted away from Antarctica then they would have had the opportunity to evolve into various species of cat including the big cats over the intervening 55 million years. If that scenario had occurred there would have been big cats in Australia. But it didn’t happen. Australia became an island with no vestige of early cats on it and therefore there was no possibility of them evolving into big as has taken place in other parts of the planet.
Some say that big cats could not survive in Australia anyway. I doubt that. There are around 50 million kangaroos in Australia. The authorities shoot them in large numbers at night in secret. The big cats of Australia which never existed would have had a field day. But there would have been a special Australian big cat adapted to the arid outback a bit like a massive sand cat.
The only wild cats that exist in Australia are feral cats which were imported to the island as domestic cats by European settlers from, it is believed, 1788 onwards. They brought in unsterilised ships’ cats. Some of them escaped and became feral cats which bred and procreated to around 2 million of them today. These are the only wild cats on the island as stated. They should not be there. It is very unfortunate for them because they are hated for their success in surviving on native species. One day long into the future, say 100 years from now, they won’t exist. They’ll have been entirely exterminated.