Antartica was part of the Southern landmass, Gondwana, which also contained present-day India, Africa, South america, Australia and New Zealand. It was located in the tropics and gradually shifted southwards, until it reached its current position.
So the question is, what was the life like in Antactica?
I know only two terresrial plant species survived to the present-day, which are Antarctic hair grass and Antarctic pearlwort. But before it reached its current position it’s obvious the life was much more abundant.
The biggest problem I think, is the fossils are now buried under tens of meters of ice blanket, so compared with other continents we know a lot less.
But anyway, tell me what you know about the Antartica life (land plant and animals) AFTER the extinction of dinosaurs, and BEFORE it reached its present southpole location. Thanks.
Sure if the whole continent was exposed you’d find a lot more but considering it was joined to Australia not that long ago, we have a pretty good idea that before that the the flora and fauna was very similar to Australias fossil record.
Antarctica split from Australia well before it split from South America, which is why the Eocene fossil record of Antarctica is highly similar to that of South America, and utterly unlike that of Australia. That’s also why marsupials made it from South America to Australia via Antarctica, but South American placentals never made it past Antarctica.
They weren’t all marsupials by any stretch. There were several different groups of marsupials, including opossums and the ancestors of Australia’s marsupials. But there were also relatives of the armadillos and a several of the more bizarre South American hoofed animals as well.
Basically Antarctica seems to have had the same mammal suite as South America, though a little less diverse in species terms because it was so damn cold.
Shame that the placentals never made it to Australia before the human influence except some bats. Just a single semi-domesticted dog (dingo) caused mass extinction of marsupials, and made the Tasmanian tigers extinct on mainland, that’s just an example on how inefficient the marsupials are when it comes to best-utilize the available resources.
Marsupials simply are not competitive compared to placentals. One example is how they utterly failed to effectively colonize the mountain ranges in Australia, while in other parts of the world where the condition on the mountain terrain is much harsher, the placentals still thrive (e.g. goat-antelope species, camellids, hyrax species, marmot species, carnivores such as puma and snow leopard).
From what you said though, it appears that the Southern Ungulates, are even less competitive, because they can’t even compete against the marsupials in Australia and became extinct there. No wonder they got wiped out so quickly when the true ungulates from North America arrived with the land bridge.
Placentals arrived in Australia around 10 million years *before *the marsupials. They just didn’t arrive from South America. They were never common and they later became extinct.
Before humans arrived Australia had equal numbers of of placental mammals andd marsupials, just as it does today. Far from “some bats” Australia had huge numbers of species of bats and rodents.
No, it didn’t. Not only not a mass extinction, there is not a single species extinction that can be clearly attributed to the dingo. Maybe, just maybe, they contributed to the extinction of the Thylacine or Devil from the mainland, but the majority of ecologists accept that at worst they contributed to their demise by assisting human hunting.
So that’s a grand total of two species at the most extreme. Not really amass extinction.
No, it’s an example of gross ignorance of the facts.
I know the Victorian idea that marsupials are somehow inferior has held on longer than the idea that Black people are somehow inferior, but the two ideas have exactly the same roots and they both have the exact same evidence: none.
Marsupials are objectively much more efficient than placentals when it comes to utilising resources. A kangaroo will live on about 75% of the amount of grass needed to feed an identically sized deer or antelope. A quoll will survive on just half the number of kills that would to feed a fox. An opossum needs about 2/3 the number of calories of a raccoon.
Placental mammals are profligate energy users and incredibly inefficient. They are essential animal weeds.
In the real world we have three natural experiments: Australia, South America./Antarctica and the rest of the planet. In Australia marsupials dominated and placentals became completely extinct extinct. In south America, marsupials completely dominated the carnivore/omnivore niches and placentals were restricted to herbivory. In the rest of the world placentals became completely extinct.
IOW we have seen the results of three natural experiments and the results are a perfect random spread.
In terms of artificial experiments, we simply have to consider that for over 100 years there were attempts to introduce over 700 placental mammals species to Australia. A grand total of 12 managed to survive in the face of competition form the native marsupials.
There is no justification of any sort for a claim that marsupials are not competitive with placentals.
Firstly, what mountain ranges in Australia?
Australia is the flattest continent on the planet. Mainland Australia only has one mountain range that is even detectable to the naked eye: the Great Divide. Even that disappears into a gentle slope for large parts of its length. There are a few isolated ranges of hills in the 400-1500m range, but they are insignificant geographically. Australia is incredibly flat.
Secondly, and probably because of this, Australia is home to the greatest diversity of mountain adapted mammals in the world. There are over 20 different species of rock wallabies alone, compared to the single species of Mountain goat found in North America or the ten species of mountain ungulate found in Asia.
I have no idea where you are getting this stuff from, but it is utterly incorrect. At best it is outdated by 50 years, but much of it has simply never been accepted by any ecologist anywhere
Ahh, no. What I said was (and I quote) “marsupials made it from South America to Australia via Antarctica, but South American placentals never made it past Antarctica”. Ungulates could hardly become extinct in Australia when they never made it to Australia.
But that is rather beside the point, because your whole thesis that marsupials are somehow uncompetitive has no basis in reality.
The southern ungulates (toxodonts and liptoterns) were not “wiped out so quickly” after the Panama land bridge formed. At least some of them co-existed with the northern ungulates for three million years or more. Toxodonts moved north as far a Mexico. The last surviving litoptern, Macrauchenia, became extinct only about 10,000 years ago. Both may have fallen victim to paleoindian hunters rather than competition with northern ungulates.
It’s not clear that the decline of the marsupial carnivores of South America was directly due to competition with placental carnivores; they were already extinct before most of the placentals arrived from the north. While they may have suffered from competition with members of the raccoon family that arrived before the land bridge was complete, they also had to compete with the phorusrhacids, large flightless carnivorous birds, as well as opossums, which were fellow marsupials. See here.
Ok Blake, it seems the ecological myths, combined with a false sense of Australian nationalism, have clearly clouded your judgement and made you unable to make objective judgement. You are simply biased against placentals. I tell you what, I care about the truths and the truths only.
All this “evidence”, came from a SINGLE teeth. It is not substaintial.
Australia had only 2 genera of bats, that is hardly “huge number”.
And what the heck is the “equal” number you talking about? Species? Quantity? Without defining what “number” you are refering to the discussion would be pointless. You don’t seem to be able to talk in more scientific terms.
In your mind, the imaginary early placentals got extinct due to over-competition from early marsupials, where is YOUR evidence then? How can you clearly contribute their disappearence to the marsupials? NONE. It is so obvious that you are biased against placentals.
Typical liberal/socialist mindset. Turning every debate into some politcal-correctness issue. Ever heard of Reductio ad Hitlerum? That’s excactly where your
“arguments” are coming to.
Oh really. How come rabbits became so rampant. How come camels, water bufflos, dingos, foxes and so on became so widespread to the point the Australian government had to intentionally try to exterminate them?
I tell you what, it is well-known that ruminants are the most efficient herbivores due to their ability of ruminating.
And deers DON’T feed on grass like kangaroos. Deers are mostly BROWSERS, not grazers. but clearly you have no idea such distinction even exists, judging by the fact you lumped them together.
Totally laugable eco-bargage, fed by marxist-eco professors. Just because placental MIGHT tend to use more energy does not make them inefficient. By your logic reptiles are more efficient as they use even less energy. You clearly do not understand what “efficiency” is about.
And calling placentals “weeds”? How about you end your own life, you are placental yourself hence by definition you are weeds. And don’t eat beef, pork, lamb, milk any more. They are weeds.
Totally wrong. You have absolutely NO IDEA about the natural world.
Seriously, since when did jaguar, mountain lion, tapir, racoon, coyote, deers, rodents and so on became marsupials? In SA, after the land bridge connected NA with SA, all marsupials got wiped out by placentals except the small-sized possum species.
That was what would happen to Australia, if a similair event happened.
I assume you meant marsupials. Otherwise this would be the most stupid statement I’ve seen in this forum.
Only in your imaginary marsupial utopia, is it a perfect random spread. It is obvious that on all landmasses where marsupials and placentals compete, the marsupials got nearly wiped out, and in case they survives they only occupy very limited niches.
Non-sense. There have never been so much introductions, and even if there were, most were very small-scale done by common people with little skills, and most were just for destination such as zoos and carnivals, hardly an “introduction” intended to establish viable, long-term population in Australia.
And for the placentals that are present, they are remarkly successful. This is agreed upon by your fellow “ecologists” which is why they are so eager to exterminate them, because they think they out-compete and out-predate on the marsupials.
The wallabies are hardly adapted to mountain life, compared to the mountain animals in other parts of the world. The environment they live in would be considered paradise for these mountain placentals in the outside world.
And rock-wallabies are now declining due to competion from goats, sheeps,and rabbbits. This tells you a lot.
I reach my conclusion through independent and logical thinking, rather than taking whatever garbage from the eco-marxist professors. And I have just shown you how incorrect you are.
You have no idea what I was talking about, do you? First, this reply is irrevelant to my point, you are replying to something I never meant because you did not understand what I said. Second, you clearly have absolutely no idea what Southern Ungulates are, do some research before you speak.
The presence of large flightly carnovorous birds might as well be an indicator of the inefficiency of the marsupial carnivores. They became extinct shortly after the arrival of plancetal carnivores such as the true sabre-toothed cats.
Gastornis, another genus of large, carnivorous birds, was apex predators in late Paleocene and Eocene in Europe and North America. But they went extinct when mamallians began to out-compete them.
Taking from wikipedia.
The mid-Eocene saw the rise of large creodont and mesonychid predators to ecological prominence in Eurasia and North America; the appearance of these new predators coincides with the decline of Gastornis and its relatives. This was possibly due to an increased tendency of mammalian predators to hunt together in packs (prevalent especially in hyaenodont creodonts). The** fact that no birds appear to have ever weighed much more than half a metric ton suggests that they were restricted in their ability to evolve to larger and larger sizes, and thus in their ability to out-evolve apex predators by sheer bulk as mammals are often able to do** (see Cope’s Rule).
The conclusion is, placental carnovivores were able to evolve to out-compete the large carnivorous birds. They first managed to do that in Europe and NA, then when the land bridge is formed, they did the same to the SA carnivous birds. Only this time it was even quicker because the mammal carnivores did not have to co-evolve with the SA birds to out-compete them.
On the other hand, the marsupials failed to out-compete against the terror birds. The terror bird continued existence only proved that marsupials were inefficient, in-competent predators, compared with placentals.
I just want to add a point. It’s not just the mountain species, or the carnivores, even the ant-eating marsupials are inefficient compared to the placentals.
The numbats simply “suck” compared to the placental ant-eaters. They have the least skills when it comes to survival and ant-eating. They fail in almost EVERY category. Only “advantage” is maybe they look the cutest ant-eater so I would have no problem owning one as a pet.
ability of foraging
The numbats, according to wiki, do not have claws that are “strong enough to get at termites inside their concrete-like mound, and so must wait until the termites are active”. Almost all other ant-eaters do.
Pangolins, aardvak, and Amercain ant-eaters, all powerful enough to do that.
protection against predator
Numbats are suffering because of RED FOXES, I mean, seriously, red foxes… small-sized canine species have never been a problem for other ant-eaters.
In addition, numbats are UN-ARMORED, and cannot dig quickly.
Heck, even the Echidna got spines which protect them from predators, and they are mono-tremes…
It’s pathetic that numbats are only able to survive because of protection from human.
Cite? The Borhyaenidae is generally considered to range to about 5 million years ago, that is, before the Panama land bridge became complete and before most placental carnivores reached South America. Smilodon originated about 2.5 million years ago. I am not aware that any other sabre-toothed genera reached South America.
Some Phorusrhacids were able to compete with placental carnivores, for example Titanis of Florida, which coexisted with them for a good 3 million years.
This is a very simplistic view. There is no real evidence that the South American carnivores became extinct because of competition by placentals. As I said, they declined long before major carnivore groups even reached South America.
How do you know? Moreover, even if it did happen, the placentals did not seem to be affected much, which in turn would suggest they were more adaptable.
What I think is, marsupials and placentals lived alongside with each other for millions of years during the dinosaur age. But once the dinosaurs were gone, the mammals were able to diversify quickly, and the placental were simply superior to marsupials and replaced them everywhere except isolated places like SA and Australia, and the marsupials in SA got wiped out when the placentals arrived.
That last comment [in post #17] is incorrect. You can’t consider that there are 7 independent “experiments,” but as Blake says, only three. Europe/Asia/Africa/North America have been effectively one land mass for most of the Cenozoic (the “World Continent”, while Australia and South America were isolated island continents. Placentals dominated the World Continent, marsupials Australia, and South America had marsupial carnivores and placental herbivores. (We don’t know much about Antarctica.)
If there is a competitive advantage, it is between animals that have evolved on larger land masses have an advantage over those from smaller landmasses. If animals from the World Continent have an advantage over those from the island continents, it’s likely due to the fact that they come from a larger land mass.
How do you know? Like I said, your view is largely speculation and is not strongly supported by any real evidence.
As I said, this is simply incorrect. Stop repeating it unless you can produce some evidence that it’s actually true.
First of all, marsupials did not get “wiped out.” Opossums are diverse and widespread in the Americas, with over 100 species in the Americas in various ecological niches, and one is even common in North America.
Second, the marsupial carnivores in South America became extinct well before the arrival of most placental carnivores, so their demise can’t be attributed to that.