Evolution: Shouldn't the Kangaroos be at least similar to their ancestors & not so different?

Question

www.cnn.com/2006/TECH/science/07/12/australia.fossils.reut/index.html PLEASE read this article at cnn.com

I am confused...make fun & this is NOT an evolution/creationism question so if that is ur thing don't bug me... my ? is Why are the kangaroos so very different from their ancestors. Generally speaking we are like apes, so u can see the supposed flow from ape to man. However to go from 4 legged galloping carnivore to 2 legged hopping herbivore seems not to flow as neatly. Does anyone ACTUALLY know anything about this?? Again please, I really just want to see if I can get an intelligent answer not sarcasim, wit or mean responses. THANKS

Answer 1

Let's clear up a few points first, OK?

The ancestors of modern kangaroos were NOT "legged galloping carnivore". You have completely misread the article, which is poorly written. But you get that when popular journalists try to write science articles. All that the article says is that the ancestors of modern kangaroos looked nothing like their forebears. It also adds the word "ferocious" implying that these carnivorous animals were the forebears of modern roos. Let me assure you they are not. The journalist just added that bit. I know Sue Hand and she would not have said such a thing. That is a misattributed quote.

The ancestors of modern kangaroos were hopping herbivores just like modern kangaroos. They in turn derived from a species of small tree-dwelling marsupial somewhat like an opossum, but that is going back many hundreds of millions of years. Whether those distant ancestors were omnivorous we don't know but they were PRIMARILY herbivores. Nobody is quite sure exactly at what stage macropods adopted a hopping gait and primarily herbivorous lifestyle but it was many millions of years before these carnivorous roos existed.

The described carnivorous roos are a side-branch of the kangaroo family. By the time they evolved roos were already firmly established as hoping herbivorous animals. These carnivorous animals evolved from hoping kangaroos, not the other way around.

IOW a fairly typical looking kangaroo adopted a carnivorous lifestyle and gradually lost the ability to hop. That might seem unusual but it is certainly no more drastic in evolutionary terms than whales losing all their limbs and returning to the oceans, or even humans adopting bipedal locomotion.

Although these roo finds were interesting they surprised nobody in scientific circles. We already knew that such animals must have existed, we just hadn't found them yet. The reason we knew they must have existed is that we already knew that the Thylacines were descended from hopping kangaroo-like ancestors and had evolved into very dog-like forms. That is the reason why the Thylacines were the only predatory mammals to have a fused lower spine and tail, just like kangaroos. So evolutionary theory had already predicted that there must have existed semi-bipedal, carnivorous kangaroos that made transition to dog-like form. No surprises there. The only surprise is that these things existed so late, well after true thylacines already existed, which suggests that kangaroos may have re-evolved a quadripedal carnivorous lifestyle multiple times.

These carnivorous branches of the kangaroo family were not in any way ancestral to any living macropod species. They were a side-group that split away form an essentially modern kangaroo form. They were also an evolutionary dead-end and left no descendants.

It might seem odd that something like a kangaroo would adopt a four-legged posture or a carnivorous lifestyle, but really it isn't. Macropods always have and still do WALK on all four limbs. Only when they are travelling fast do they hop. So reverting to a quadripedal gait isn't a big move for macropods, far less so than for humans.

Similarly many of these early macropods would have been opportunistic omnivores, as most "herbivores" are today. We know today that animals such as deer, sheep, squirrels and kangaroos will all eat meat such as insects and nestling birds when they can get it. These early kangaroos would have been similarly opportunistic and gradually become truly predatory. However to make an effective predator requires an ability to stalk as well as grapple prey and that in turn means adopting a more efficient quadripedal gait since it is hard to stalk while bouncing up and down.

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Snakegirl said>>>>Once placental mammals evolved most
>>>>>> marsupials were pushed out everywhere else.

Not even remotely true. Placentals and marsupials co-existed in Australia from the very beginning and the placentals became extinct. In South America marsupials still make up the vast majority of the non-rodent mammal species and until a few million years ago made up ALL of the carnivore fauna. Only in Eurafrica were the marupials eliminated.

>>>>There are no native placental mammals in Australia

Also not even remotely true. There are almost as many native placental species in Australia as there are marsupials. Between the rodents and bats there is a pretty nearly even split between marsupial and placental mammal species in Australia: around 130 species of marsupials and around 125 species of placentals.

The most intriguing aspect of Australia's mammal fauna is the lack of radiation of the placentals. With one exception, a rat that has become an aquatic predator and filled the ecological niche of an otter, the placentals in Australia have remained very conservative in form and function. No australian placentals have evolved to fill the niches occupied by squirrels, beavers, capybara and marmots elsewhere.

All that seems to suggest that placentals simply can not compete against an established marsupial fauna. The reason a rat managed to occupy the "otter" niche is that no Australian marsupial ever evolved to occupy an aquatic environment, probably because pouch young can not survive immerison. One South American marsupial species didi evolve an aquatic lifestyle by sealing the pouch, but such an adaptation never evolved in Australia so the niche remained unexploited across the entire continent until the second wave of placentals arrived.

Answer 2

Kangaroos said a direction uncomplicated to distinct animals, for instance Pandas, they have a carnivore's digestive equipment yet a herbivore's eating routine. Iguanas are insect eaters yet Galapagos' ones are algae eaters. So a substitute in eating routine isn't uncommon in any respect. you're saying we are like APES, yet maximum of their monkey ancestors are 4 legged, and maximum of apes are very just about bipedal, people are the in common words real bipedal among primates. So on the top, kangaroos are bipedal because it is swifter than the way its ancestors were. And are herbivorous because grass is a good food.

Answer 3

Well, the infraclass of Marsupialia is incredibly varied. Dasyurids (quolls, tasmanian devils) are carnivorous marsupials that walk on 4 legs, so maybe it isn't too much of a stretch. In terms of evolution, if I remember correctly marsupials were once much more widespread than they are now, and didn't originate in Australia but rather migrated there. Once placental mammals evolved most marsupials were pushed out everywhere else. There are no native placental mammals in Australia, so that means that marsupials were left to evolve and branch out to fill many different niches, which would explain why they are so varied.
Check out http://en.wikipedia.org/wiki/Marsupial

Answer 4

look at the horse it resembled more like a dog,who has all the answers beside that millions of years things has changed