There would be or should be trails of fossils or bone remains of kangaroos, from Mount Ararat, Turkey, to all the way to Australia, if you seriously believe in a biblical, global flood, pegg. There should be remains in Central Asia, possibly in South Asia (Indian subcontinent) and continental South-East Asia. There are none.
In fact, evidences of all animal migrations, large and small, should originate from Mount Ararat. According to the Genesis, Noah's Ark landed on the peak on one of Ararat mountains, presumably the highest peak, if you take the Genesis literally. But every little remains are found at this attitude.
And the supposed flood (of the bible) supposed to take place between 2340 BCE and 2104 BCE. There are no evidences of flood of the magnitude anywhere between those time, because many of the Sumerian/Akkadian and Egyptian civilisations were still flourishing, historically and archaeology.
If the flood happened in the 2nd half of 3rd millennium BCE, then archaeologically you would find devastation of the flood at that POINT OF TIME, in the Bronze Age cities and towns, and geological strata. No such devastation can be found.