From giant rodents to miniature elephants, the tropical archipelago of Indonesia used to be teeming with weird and wonderful creatures. In an expedition to understand why so many of these incredible animals no longer stalk these forest, researchers have detailed the species that once lived on one such island called Sumba.
As part of a group known as the Wallace Islands, this region is of particular interest to biologists simply due to its pure oddity. Located as a gateway between Asia and Australia, the islands have a bizarre mix of creatures from both continents that have subsequently been isolated on islands for thousands of years.
On Sumba, it seems this led to the evolution of multiple species of giant rats, the massive komodo dragons, as well as the smallest elephant species (a pygmy stegodon) yet discovered. This study, published in the Proceedings of the Royal Society B, is the first to describe in detail the ancient fauna that once lived on the Indonesian island of Sumba.
“These discoveries offer a fascinating and poignant glimpse at a lost world, as many of the animals that evolved in isolation on islands in Wallacea were lost following the prehistoric arrival of modern humans,” says lead author Dr Samuel Turvey in a statement. “Understanding the past diversity of these islands can give a unique insight into the processes of evolution, explaining why some species were lost while others survived.”
Interestingly, the species that lived on Sumba were similar to those that are known to have evolved on the nearby island of Flores, which raises some fascinating possibilities. Flores is the island on which anthropologists made the explosive discovery of the “hobbit” people, or Homo floresiensis, a species of human that stood only 1.1 meters (3 feet 7 inches) tall.
The researchers of this latest study suggest that if many of the other animals that lived on Flores were also able to cross the strait that separates the islands, there could be the possibility that H. floresiensis also made this journey too. This might not be too far-fetched, considering their ancestors would have had to have crossed open water to get to Flores in the first place.
What needs to be done now is to look at the differences between the fauna found on both islands, to see if these other species were indeed moving from island to island. If they do seem to be from a single or closely related population, then it would support this hypothesis. Equally, if it turns out that the different species individually grew and shrunk as they were all exposed to similar environments and thus similar selective pressures, then it would imply they were far more isolated.