The Origins and Evolution of Madagascar’s Modern Vertebrates

Dr. Karen Samonds, Northern Illinois University, discusses how fossil discoveries in Madagascar shed light on the island’s evolutionary history, and how the remaining species can be preserved.

Madagascar is one of Earth’s biodiversity hotspots that has some of the most unique species of animals on the planet. However, these pale in comparison to the diversity of animals that existed on the island in the prehistoric past. Madagascar has a dramatic geological and tectonic history that has greatly shaped today’s plants and animals. The details of how, when, and from where the ancestors of the present-day animals arrived still remain poorly known.

Madagascar has been isolated from all other landmasses for nearly 90 million years, well before the arrival of most of the ancestors of animals currently living there. If these animals were not stranded when the island separated, how did it acquire its unusual animals and plants, especially those with close relatives in distant landmasses?

The Cenozoic Era fossil record (66 million years ago to the present) remains our best source of information about the origins of these groups of animals, but much of this fossil record is missing. Recent palaeontological surveys have produced the first collection of Cenozoic vertebrates from Madagascar, including fishes, sharks, crocodylians, turtles, sea cows, dolphins, and, most significantly, the recent discovery of land-dwelling animals.