When the continent separated some of the same species ended up on different continents. This is because the continent was so large the species were distributed across the continent. So, when it split, some were on one side and others of the same species were on the other side.
Plate tectonics
Evidence of species moving from one continent to another can be found in the fossil record, where similar species are discovered on now-separated continents, such as the presence of Mesosaurus fossils in both South America and Africa. Additionally, the distribution of living species, such as the lemurs of Madagascar, suggests historical land connections. Genetic studies also reveal similarities among populations that indicate past migrations facilitated by land bridges or continental drift. Lastly, geological events like plate tectonics have shaped the movement of continents, leading to the dispersal of organisms.
First of all, if you're a creationist, ask your local representative of whichever divine being you believe in. Ignore the rest of this post, as creationists will consider it heresy. It has to do with genetic drift - the foundation of evolution. Australia is a very isolated continent, lacking any land bridge to another continent. It is thus isolated. Furthermore, the climate of Australia differs significantly from the other 6 (for that matter, the other 6 also have unique climates), meaning adaptations in Australia need to solve a different set of problems. When a population of a species is isolated from the rest of that species, as those of Australia were whenever continental drift separated Australia from what was left of Pangea (the megacontinent from when all of the continents were connected), its genetic traits slowly begin to differ from the original species - this is called genetic drift. Eventually, instead of 2 separated populations of a single species, we have 2 separate species. One of these species is in Australia, the other in the Pangea remenant (probably just Eurasia at that point). Why they are so radically different in Australia than in most other continent combinations is primarily due to the amount of time since Australia separated from Pangea. South America and Africa split fairly recently. The geological evidence has not yet eroded away, and is easily identified by geologists. Furthermore, the genetic differentiation has not been enough to make a significant difference between Jaguars and Leopards (well, from a layman's perspective). Just going from the amount of genetic drift, I'd suggest that Australia split from the other continents fairly early in the disintegration of Pangea, perhaps even the first significant land mass to split off (other than possibly Antarctica, which is barely relevant in a discussion of evolutionary diversity.
Millions of years all of the continents were all combined into one super continent called Pangea, but because of convection currents in the mantle, continental plates began to break up. So animals that lived on plate borders were separated onto different continents. But if you are talking about present day animals they were probably shipped by humans for numerous reasons. If it is birds and fish you are talking about they simple swim or fly there during their migration.
Squirrels are found in an extraordinarily diverse range of habitats, from desert conditions to extremely wet rain forests. Squirrels naturally occur in all continents except Antarctica and Australia.
The continents used to all be connected, which means animals were free to roam. If they were free to roam, then they obviously spread out throughout the continent. So when this continent separated, the same species ended up on new continents because they had originally spread out.
When the continent separated some of the same species ended up on different continents. This is because the continent was so large the species were distributed across the continent. So, when it split, some were on one side and others of the same species were on the other side.
The continents used to be one continent. The species all lived on one continent since there was only one, so they were distributed throughout. However, when the continent began to split and more continents formed, these species were separated. Then, evolution and adaptation began to set in (as it had before though) and these species became even more different from each other.
There are some same species of both plants and animals located on separated continents. This is because the continents were all at one point joined together in one super continent: Pangea, but separated some 200 million years ago. fossils
The continents used to all be connected, which means animals were free to roam. If they were free to roam, then they obviously spread out throughout the continent. So when this continent separated, the same species ended up on new continents because they had originally spread out.
Plate tectonics
You can tell because if that form of species originated in a certain area and if the fossil is found in a different area or continent you can tell that the species traveled then the land mass or super continent Pangaea separated and that species landed over there Example: If a species of animal originated in Africa and that specie was found in South America you can tell that that specie during the Pangaea time that species traveled, died, then the continents divided into the different forms to form the new day land form
Fossils of similar plants and animals found on continents that are now widely separated suggest that these landmasses were once connected. The distribution of these fossils across different continents supports the theory of Pangaea, which posits that all current continents were once joined together in a supercontinent. This evidence helps explain how species were able to migrate and evolve across different landmasses before continental drift separated them.
One piece of evidence is the fit of the continents' coastlines, particularly between South America and Africa. Another piece of evidence is the distribution of similar fossil species across continents that are now separated by oceans.
The discovery of fossils of the same organism on different continents suggests that these landmasses were once connected as part of a single supercontinent. This supports the theory of plate tectonics, which explains the movement of Earth's lithosphere. The distribution of these fossils provides evidence for the movement of species across land bridges or through continental drift over millions of years.
Evidence supporting the theory of the supercontinent Pangaea includes the jigsaw-like fit of continents, similarities in rock formations and mountain ranges across continents that align when continents are brought together, distribution of fossils of identical species across distant continents, and similarities in ancient climates and geological records found on separate continents. These pieces of evidence work together to suggest that the current continents were once part of a single landmass.
Alfred Wegener presented several lines of evidence to support his theory of continental drift, including the fit of the continents like a jigsaw puzzle, similarities in rock formations and mountain ranges across continents, and the distribution of fossils of the same species on different continents separated by oceans.