Madagascar is like a look into the past. Because it split from mainland more than a
million years ago, the ecology has lived in isolation allowing ancient species to leave descendants up to modern day. It’s because of this isolation that about 90% of all life on of Madagascar’s is endemic. It’s why Lemurs are alive today and not anywhere else on earth because Madagascar lack the suborder Haplorhini( monkeys, apes, and humans) which out competed them millions of years. And the reasons lorises bush babies, and pottos ( suborder Strepsirhini that includdes lemures) survived in pockets around the world is because of there nocturnal lifestyles that allow them to be active at night instead of the other suborder. So, if you ever thought Lemurs and lorises looked ancient you most definitely would have been right. Also because of there time in a evolutionary isolation from the rest of the world Lemurs have become incredible with a lack of predication and ability to take advantage to all the diverse ecosystems Madagascar had to offer. One of the most interesting finds that have stunned paleontologists are a family called the sloth lemurs or Palaeopropithecidae, which I still can’t pronounce.
They are interesting not because they are related to sloths. Which even to this day I still don’t know why that name stuck. It’s because of there enormous size that no living lemur can compete with. But like modern lemurs based on the fossil record they where extremely diverse. Varying in size and shape, one even having the skull the size of a gorilla and must have weighed a couple hundred pounds. But, for there size these giants
dentition shows they all had vegan diets, eating on mostly fruits and leafs. And based on there size and the fossil record there most likely was never a lot of them living at once per generation, but some of the species did live to only a couple thousand years ago. They most likely where very close to their habitat making them less adaptable to sudden changes in the environments. And there is some evidence of climate change in parts of Madagascar as well as early human settlements in regions that used agriculture to change the environment around them. There is even fossil evidence of these large lemurs with cut marks on their bones, signs of butchery for either their meat or fur. So the extinction of these animals might have been from human of the environmental change but well probably never know.
On a brighter note. A few years ago now there was a discover of sloth lemur fossils found in Tsimanampetsotse National Park. Some of the finds had complete skeletons which will help to understand more about there anatomy.