A study, published in 1985, notes that the bones of the marsupial lion are most frequently associated with two genera of kangaroos, Macropus and Sthenurus, including giant kangaroos.
The bones of extinct giant kangaroos bearing marsupial lion toothmarks, found in the Lancefield Swamp in Victoria, suggest that, like the sabretooth cats of the northern hemisphere, it fed largely on the internal organs of its prey.
But all this tells us is that kangaroos featured in its diet. I believe we might be able to go further, and speculate that Thylacoleo carnifex was a highly specialised kangaroo hunter.
Kangaroos, some of which are much bigger and heavier than the marsupial lion, seek to escape by leaping.
An animal that can stand on its hind limbs and reach with its elongated forelimbs has a better chance of grabbing one than an animal that’s strictly quadrupedal.
Because kangaroos are so tall, Thylacoleo couldn’t go straight for the throat. Even standing on its hind paws it wouldn’t have been high enough, especially if it were hunting giant kangaroos.
But what it could have done was to hook onto the kangaroo’s belly or chest and use those tremendous forelimbs to pull itself up.
Attached to a very large, very powerful animal, with no purchase on the ground, the marsupial lion would then find itself in a perilous position.
It had to bring down its prey quickly, or find itself thrown from pillar to post.
The need to deliver sudden death might explain those extraordinary teeth and that powerful bite.