Populating Madagascar

In chapter 12 of On the Origin of Species, Darwin argues that the non-existence of certain animals on oceanic islands is evidence against the theory that the flora and fauna of the world were brought into existence by acts of special creation by a divine being. Here he is on frogs, toads and newts:

With respect to the absence of whole orders on oceanic islands, Bory St. Vincent long ago remarked that Batrachians (frogs, toads, newts) have never been found on any of the many islands with which the great oceans are studded...This general absence of frogs, toads, and newts on so many oceanic islands cannot be accounted for by their physical conditions; indeed it seems that islands are peculiarly well fitted for these animals; for frogs have been introduced into Madeira, the Azores, and Mauritius, and have multiplied so as to become a nuisance. But as these animals and their spawn are known to be immediately killed by sea-water, on my view we can see that there would be great difficulty in their transportal across the sea, and therefore why they do not exist on any oceanic island. But why, on the theory of creation, they should not have been created there, it would be very difficult to explain.

It is easy to make sense of their absence if islands have been populated by migrating creatures. Frogs, toads and newts can't hop over the sea or swim there, as sea-water kills them. Birds, insects and the seeds of plants can be carried by their own steam or by the wind, which is why you find them there.

But what about Madagscar? There you find mammals, notably the lemurs, who could not have swum or be blown or (clearly) flown across. There's no evidence of a now-non-existent land-bridge either over which they could have walked. Research published this week in Nature by researchers in Purdue University and Hong Kong University claims that the ancestral species of modern-day Madagascan fauna could floated there on bits of wood and, once there, evolved in isolation into the distinctive species we see now:

Here's a summary of the findings from Purdue University.