You fail to identify any mechanism.
It is obvious when you compare animal to animal. I’ve already illustrated the numbat example pretty well. And I also pointed out how ruminants are more efficient than kangaroos.
Your larger landmass point is without evidence, and pure speculation.
What does this even mean.
Nevermind if you can add nothing, stay out and I will too.
I just thought of something new, related to what Blake said.
Blake and his marxist-eco professors or whatever, claim that placental animals somehow “wastes” more energy than marsupials.
First, I am not sure about the validity of that claim. Modern ecologists, influenced by marxists, do everything to demonize so-called “non-native” species.
Second, is what I am trying to present now. That is, they are ignorant of what energy is. If these so-called “ecologists” actually understand the physics taught during highschool, they might not be quick to invent such myth as “wasting energy”.
Why? Because basic physics tells us, energy never disappear. They merely transform into another form. Assuming the claim that placentals somehow consume more energy than marsupials, it simply means they are more efficient energy users.
Almost all energy of an organism ultimately comes from the sun. When the sun shines, the plants convert solar energy into chemical energy via photosynthesis. Then they are eaten by herbivores which consumes its own chemical energy to obtain more chemical energy from plant matters, and they are in turn eaten by carnivores who spend chemical energy in pursuit of more chemical energy from the meat of the herbivores.
Therefore, energy is always there to take, but taking them require energy itself, so different organisms spend different amount of energy in order to obtain more energy.
For instance, areptiles have low energy requirement compared to . They are cold-blooded (i.e. do not need energy-expensive thermoregulation), so they can require less energy to survive because their energy expenture is low. A nile crocodile can survive months without food while a lion would turned into a skeleton already.
But this is done at a cost. Though reptiles do not need expensive thermoregulation, it also means they are less adaptable at colder climates than mammals. Mammals can survive in the arctic by converting chemical energy into heat energy, aided by thick coat or fat. Reptiles just freeze to death.
Therefore whether a species is more “advanced” might be indicated by the level of energy it could utilize. Humans, for example, have become the master of energy, to a level not a single other species of organism have ever achieved. And within human itself such distinction is still valid. More advanced people are able to utilize more energy than the less advanced. While people in the civilized world are able to obtain chemical energy from food in a large scale cheaply, exploiting energy from sources such as electricity, and even “wasting” massive energy by burning them in a few seconds in rocket-fuels for some of the fortunate ones for space tourism, the less advanced still rely on charcoals and have to spend their own energy just to carry water from the rivers because there is no running water.
Tekeli-li! Tekeli-li!
The Great Old Ones were the malign Elder Gods who, among other things, inhabited Antarctica in Days Of Yore (and Gore and Vore) in the Chulhu Mythos of H.P. Lovecraft and his circle of horror writers. It was in the nature of a recondite witticism.
This is a fairly well known hypothesis. The mechanism is that animals on larger land masses are confronted by competition from a larger number of species, and thus have their competitive capacity honed.
Here’s some detailed discussion of the hypothesis.
No, it’s not particularly obvious. Cherry-picking examples is not evidence.
There’s as much evidence for it as your speculation.
How’s that cherry-picking? Seems to me you are ignoring the overwelming evidence.
And for the theory, I know it very well. However you applied it wrong, which is why you came to the wrong conclusion.
Cane toads are a major pest in Australia, so I take it this means anurans are superior lifeforms as well?
What introduced species do well is really not an indicator of some imagined subclass superiority- hell, New Zealand Flatworms are becoming a serious problem in the UK, and they’re flatworms. All it can possibly mean is that that single species has found a niche where it is, at least in the short term, outcompeting one or more native species, which can take place for a variety of reasons, including being more adapted to the environmental change being brought about by humans. If every time a new group came along it wiped out the previous donimant group, we wouldn’t still have birds, reptiles, amphibians, insects…
Oh, and for someone who claims to be only concerned with the facts, comments like:
don’t half make it sound like you have some odd personal grudge against marsupials.
Ever considered campaigning against monotremes instead?
You haven’t presented any overwhelming evidence. You’ve presented a couple of examples. That’s cherry-picking.
If you had heard of it, then why did you ask me to identify the mechanism?
Whatever are you talking about? Please explain how I applied it wrong. And how do you know your conclusion is right and mine is wrong, exactly?
Just found more evidence of the inefficiency of the marsupials
It turned out that the top apex predator of marsupials in modern times, the tasmanian tiger, was totally incompetent, compared to placental equivalents.
From wiki:
“A 2011 study by the University of New South Wales using advanced computer modelling indicated that the thylacine had surprisingly feeble jaws. Animals usually take prey close to their own body size, but an adult thylacine of around 30 kilograms (66 lb) was found to be incapable of handling prey much larger than 5 kilograms (11 lb). Researchers believe thylacines only ate small animals such as bandicoots and possums, putting them into direct competition with the Tasmanian devil and the Tiger Quoll. Such specialisation probably made the thylacine susceptible to small disturbances to the ecosystem.[31][53]”
I mean seriously, how pathetic, a marsupial as large as the wolf, can only handle such small preys. NOW THIS IS inefficiency, or even inferiority, compared to placentals. You simply cannot deny it.
I don’t understand how you’re defining inefficiency. Predator/Prey size relationship seems an extremely bizarre definition. By that token the baleen whales (which include nine of the ten largest mammals) are vastly inferior to anything that has ever lived. For terrestrial mammals the Giant Anteater grows to more than twice the size of the Thylacine (up to 7 ft and 140 pounds) yet eats only insects as it lacks teeth. Does that make it horrible as well?
It sounds like existing on a diet of smaller than expected prey would relate first to Blake’s point about metabolic efficiency being greater in marsupials and then to Colbri’s point about specialization and lack of competition leading to animals that fair poorly when introduced to new species.
On the other hand, according to Wiki the recently extinct Thylacoleo was the most remarkable mammalian carnivore of all time:
By your own criteria, this means that marsupials must be superior to placentals.
Note that the Thylacoleo probably became extinct due to the arrival of humans in Australia, not because of any competition with placentals.
So back to the OP. is it still the case that no true mammal fossils have been found in Antarctica? So far both Marsupial and proto-mammalian fossils have been found but no modern mammals?
Is that correct?
Nitpick: aren’t humans placental? 
Why the terminology of value judgment? What’s “pathetic” about an animal’s diet?
I think you meant to say “In the rest of the world *marsupials *became completely extinct.”
Other than that, I agree with you nearly 100%.
More evidence supporting my theory that the relatively success of South American terror birds before the Great American Exchange, was due to the inefficiency of the marsupials.
from wiki:
Note the Metatherians had been regarded as marsupials, but recently it has been seperated from it but still regarded as being very closely related. Also note that it was the only carnivorous mammal in SA before the arrival of the placental carnivores with the Great Amercan Exchange, meaning the metatherians out-competed the marsupials yet got defeated by the placentals.
Dude, let it go.
This slide below just freaking NAILED IT. Marsupials are inferior. They deserve to be replaced by placentals. Australia should stop its overly-protective policies. Heck, you can’t even own a freaking HAMSTER because it is feared that these “foreign” animals would “devastate” the marsupials. LOL. Bring it on. No mercy for the losers. You don’t deserve tears when you lose the evolutionary race.
Some important parts in the slide:
II. Are marsupials inferior?
A. Lines of reasoning that they are:
B. Is the competitive disadvantage the result of their mode of reproduction?
Maybe. Their mode of reproduction limits the environments in which they can live.
Maybe not. Other factors include:
Cerebral cortex of marsupials is smaller and develops more slowly
Learning and behavioral flexibility is less developed in marsupials.
Behavior is less diverse.
They have a small number of chromosomes, which may make them less evolutionarily flexible.
Their reproductive rate is lower.
C. An alternate view is that marsupials are not necessarily at a competitive disadvantage in all circumstances. Possible advantages of a marsupial reproductive stratgey include:
Low energy requirements, spread out of a long period of time
Can quickly replace lost young