Sunday, December 20, 2020

Adalatherium

Say hello to a family of Indian mammals: adalatheres. We had jawbones for these but nobody had made sense of them. Now here's a full skeleton. Which also makes little sense. Looks like a badger but not. Hence the name: it's !loco!-therium in the Madagascar main tongue.

This island was and remains a microcontinent, but - I've just learnt - not split from Africa. Malagasy split from India, 85 mya. India had been an island-continent since Cretaceous not long after 150 mya although, arguably, from Africa (some say Antarctica). It's in the general "Gondwana" side of the mammalian tree. Meanwhile in Africa, they had such Afrotheres as the elephant; thence occasional offshoots into [South] America.

The Deccan Trap, I expect, did for most India before even Chicxulub; so Madagascar was a refuge by 66 mya.

The adalathere skeleton looks like a badger in the front and a crocodile in the rear. Those back legs, all splayed out, look great for digging emergency holes in soft earth for laying eggs. This is a monotreme - at least. It's as if this monster hadn't finished the Triassic. We're told all the paramammals like Tritylodon had died out back in the Jurassic, before India-Malagasy sheared off. But as this study points out, we're not well informed on southern-hemisphere mammalian fauna. Australia might not have had mammals at all until it was seeded from America and those are marsupial.

Cretaceous India including Malagasy, I think, would be on the South America model, generally an offshoot of contemporary Africa, Antarctica being antarctic. Some marsupials, some low-temperature primitive placentals like the armadillo.

After Chicxulub, mammals from Africa skated over there so those are the mammals they got now. Including the lemur which was European in origin.

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