|Is it possible that a fossil could make its way
from South America to Australia, and only be found
in those countries?
Fossils like the ones you describe do exist. Their
existence is explained by periods of time in our
earth's history when the continents were
connected. The most recent of these
"supercontinents" is called Pangaea. Pangaea
existed about 300 million years ago. The evidence
of Pangaea's existence include both fossil records
and geological evidence of the earth's tectonic
plates as well as mountain formations, land
So, to answer your question, it's not that the
animals that made the fossils traveled long
distances and colonized distant lands. Rather,
at the time that the animals lived, the lands
were much closer together or even connected.
It wasn't until after the species' extinction that
the land holding the fossils separated.
Well, fossils cannot really move, they are
imprisoned in rock. However, millions of years
ago, all of the present continents were located as
ONE GIANT CONTINENT. If there were animals and
plants living on this ancient land mass, and these
organisms became fossilized, then in the millions
of years since then, when the continents split up
and drifted apart, then fossils could become
Since fossils aren't living, it's not possible
for them to move anywhere--except to perhaps
roll downhill, or to drift along with whatever
continent they happen to be attached to.
It's this last point that I think you're trying to
There are many examples of similar fossils on
landmasses that are far apart today. For example,
there are nearly indistinguishable mesosaur
(freshwater reptiles) known from eastern South
America and western Africa. At the time mesosaurs
lived, however, South America and Africa were
connected and these animals lived (and died)
across this continuous landmass. Some mesosaurs
were lucky enough to become preserved as fossils.
As Africa and South America slowly drifted apart,
the mesosaur fossils also became ever more
separated. This process didn't happen overnight,
rather it took hundreds of millions of years.
This is actually one of the proofs of continental
drift! Millions of years ago, all of the
continents were bunched together as one continent,
called, Pangea. The continents move very very
slowly, only a couple inches per year. When they
separated, fossils stayed on each continent where
the animals originally died. Now, there are
fossils in multiple places all over the world that
used to be next to each other but have since
drifted away. Here's an image to help show it:
to see the image
Yes - in fact, the oldest fossils of Eucalyptus
are found in South America, but the tree is now
native only to Australia. Apparently, South
America and Australia were connected (probably via
Antarctica) between 50 and 30 million years ago,
allowing plants and animals to move between the
Let's start off with how fossils are created. When
a living organism such as a plant or animal dies,
and its body is preserved in rocks, it forms a
fossil. So we can only find fossils of an organism
in the areas where it lived.
The continents that we recognize today weren't
always shaped and located where they are today --
they're always moving at a very, very slow rate
(millimeters/year), due to plate tectonics. So
millions of years ago, Australia and South America
weren't in the same spots on the globe as they are
today. There could have been some organism that
lived in an environment that existed on both South
America and Australia, but that it didn't live on
the other continents. So yes, it is possible for
it to only be found on those 2 continents.
Good question! Over a hundred years ago,
scientists identified similar fossils on
continents that are now separated by large oceans
(like Australia and South America). This led to
the discovery that separate continents were once
connected in the geologic past, but we lacked a
good explanation of how the continents collided
and separated until the theory of plate tectonics,
which is only about 50 years old.
Many of the fossils found on the South
American and Australian continents are of plants
and animals that could not realistically swim
across a large ocean (see the attached figure),
therefore the best explanation for the wide
distribution of fossils is that continents were
once connected. The figure above that I attached (from
the US Geological Survey) shows the
"supercontinent" Gondwana, which began to
form about 600 million years ago and started to
break up about 200 million years ago. We think
that South American and Australia were "attached"
at this time and that animals and plants could
have spread across these continents.
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