How did the continental drift affect mammals in Australia?

Answer 1

The displacement and rearrangement of land masses over geologic time has

helped to create biological diversity on our planet. Without the profound effects

created by geological reconfiguration life on earth might have been very different

from the way that it is now.

Continental drift is the movement of land masses due to the effects of plate

tectonics. Originally all of the world's surface land was located in one region on

the globe, Pangea. This supercontinent supposedly began to separate late in the

Triassic Period (245 to 208 million years ago) into a southern landmass,

Gondwanaland, and the northern landmass Laurasia. Gondwanaland was

composed of the modern day continents of India, Africa, Australia, Antarctica and

South America. These continents began to break up and head towards their

present day locations only some 130 million years ago. Because these two land

masses were the only two continents on the face of the earth for about 520 million

years they are perhaps two of the most important geological structures of the last

billion years. Our modern understanding of continental drift, and the structures that

it has produced, has inexorably impacted our understanding of the fossil record

and has given us detailed information about the evolutionary history of animal

species.

The earth is populated by tens, perhaps hundreds of millions of animal species.

We can attribute this fantastic diversity, in part, to an evolutionary trend called

speciation. Speciation is a phenomenon that normally takes place when a group

of animals of the same species find themselves isolated from one another. They

can be isolated geographically by great distances, rising mountains or large

bodies of water.

They can also be isolated by biological or behavioral barriers. One species is

distinguished from another by their inability to create viable offspring together,

and this is the precise effect that isolation can have on an animal species. Once

a group of animals of the same species becomes split apart or isolated, they

begin to be changed, molded and fashioned by the hand of natural selection to

more properly fit in with their surroundings. After a period of time these two

groups begin to be so different anatomically and genetically that soon it becomes

impossible for them to procreate. This inability for two animals, that were once

the same species, to create viable offspring is called speciation.

Before 130 million B.C. the land mass of Gondwanaland was the home to many

types of mammals. Thanks to plate tectonics it was split in two to create modern

day South America and Australia. Many mammals called Gondwanaland their

home and after it split, two very different types of mammals emerged. One order

of mammal began to both thrive in Australia and die out in South America. These

were marsupials, or pouched mammals, and they evolved into modern day

kangaroos, koalas, wallabies, wombats and tasmanian devils. Infant mammals

that leave the mother's stomach and finish off their gestation period in a warm,

nutrient providing pouch are marsupials. The only type of marsupial species able

to survive in the South American continent after the break up of Gondwanaland

was the opossum. On the other hand, on the isolated continent of Australia,

almost all of the indigenous mammals are in fact marsupials.

Very soon placential mammals, (the order that we belong to) and marsupials

were on opposite sides of the globe. Today marsupials cannot mate with

placential mammals. Their genetic and anatomical differences created

unsurmountable barriers, making them sexually incompatible. The story of the

order marsupialia is perhaps one of the most dramatic demonstrations of the

effects of continental drift on speciation.

The different types of primates with whom humans were able to mate have long

since died out. At one time we were very similar anatomically and genetically to

some of the other species of primates on the planet. Humans and Neanderthals

were sexually compatible, meaning that functionally we were not two different

species. Because of behavioral differences, probably due to discrepancies in

socialization and intellect we simply did not mate with their kind very much at all.

Animal speciation can be caused by geographical barriers, sexual barriers,

behavioral barriers -and this example makes it obvious that social barriers can

prove causal as well. If some of these barriers had not existed, and if our

geographical configurations were not in constant flux then humans may never

have evolved the way that they did, or may never have evolved at all.

United Nations Farms

Answer 2

they cant, so stop dreaming and asking these annoying questions, no body likes you. get a life you annoying baby