So, you know how most Australian mammals are marsupials (the ones with a pouch)? Well, the fossil record suggests marsupials first arose in the Americas and later went on to reach Australia around 50 million years ago, probably just one lucky small species that later would become kangaroos, koalas, tasmanian devils and a bunch of other fun dudes. The thing is, as far as we’re aware, the timeline of events means they got to Australia after it got separated from the rest of Gondwana with two interesting implications:
First, that they got there through rafting, which means a couple individuals crossed some expanse of ocean on top of some floating vegetation or whatever and ended up being lucky enough to survive till they landed on a new continent. Interestingly, that’s also the main theory on how (non-human) primates got from Africa to South America.
Secondly, that they migrated from South America to a not-yet-frozen-Antarctica and only then to Australia, which means all their friends who lived on Antarctica and were lucky enough to not end up in the middle of the ocean on top of some floating tree trunk ended up unknowingly condemning their descendants as the continent slowly drifted southwards and completely froze up around 10 million years ago.
Huh…if marsupials first arose in what is now the Americas, why are modern day American marsupials so…just opossums? I would expect a greater variety where they originated than where they migrated to. Competition from placental mammals not present in Australia?
Yup. As far as I know the placental mammals on Australia arrived there much later so the marsupials had already filled most available niches at that point.
So, you know how most Australian mammals are marsupials (the ones with a pouch)? Well, the fossil record suggests marsupials first arose in the Americas and later went on to reach Australia around 50 million years ago, probably just one lucky small species that later would become kangaroos, koalas, tasmanian devils and a bunch of other fun dudes. The thing is, as far as we’re aware, the timeline of events means they got to Australia after it got separated from the rest of Gondwana with two interesting implications:
First, that they got there through rafting, which means a couple individuals crossed some expanse of ocean on top of some floating vegetation or whatever and ended up being lucky enough to survive till they landed on a new continent. Interestingly, that’s also the main theory on how (non-human) primates got from Africa to South America.
Secondly, that they migrated from South America to a not-yet-frozen-Antarctica and only then to Australia, which means all their friends who lived on Antarctica and were lucky enough to not end up in the middle of the ocean on top of some floating tree trunk ended up unknowingly condemning their descendants as the continent slowly drifted southwards and completely froze up around 10 million years ago.
Huh…if marsupials first arose in what is now the Americas, why are modern day American marsupials so…just opossums? I would expect a greater variety where they originated than where they migrated to. Competition from placental mammals not present in Australia?
Yup. As far as I know the placental mammals on Australia arrived there much later so the marsupials had already filled most available niches at that point.
That is SO COOL! Thanks