A Key to Our Earth's History
A Bit of Info:
What
is a Fossil?
A fossil is basically any preserved evidence of life.
What
is Paleontology?
Study of life in prehistoric time by using
fossil evidence.
What
Can Fossils Tell us?
Fossils are one of the most important sources of information about the
.Earths history They tell us how old a rock can be depending on how they
are found. The fossils can tell us what the environment was like when
that species was alive. They can also tell us about Earth movements, such
as mountain building and evolution of life on Earth.
Hunting
Fossils
Fossil hunting became popular in the early 19th century.
How did
Paleontologists Really Find the fossils?
Many times some paleontologists find fossils by mistake. Fossils are found
in rocks like sandstone's, mud stones and lime stones which hardened through
time.
Why
are Fossils used?
To figure out what kind of animals, plants or living things that lived
long ago.
Different
Types of Fossils
Trace Fossils- fossilized nests.
Cast fossils- formed when mold is filled in.
Mold Fossils- formed in a negative image of the organism.
Uniformitarianism Vs. Catastrophes
Uniformitariansm is a principle that states that the same geologic processes
shaping the Earth today have been at work throughout Earth's history. A
scientist named James Hutton published a book called Theory of the Earth,
in which he said that the Earth's land forms are constantly changing. They
are changing constantly but are moving very slowly!
Catastrophism is a principle that states that all
geologic change occurs suddenly. Supporters of Catastrophism claim that
all of Earth's features, such as mountains, canyons, and seas, could be
explained by sudden events known as catastrophes.
You might be wondering which theory would win the
“Battle of Theories”. Well Uniformitarianism won! It took the work of Charles
Lyell, for people to actually consider uniformitarianism.
From 1830 to 1833, Lyell published three volumes, called Principles
of Geology, in which he reintroduced uniformitarianism. He successfully
challenged catastrophism. Lyell saw no reason to doubt that major geologic
change happened the same way in the past as it does in the present gradually.
Fossilized!
There
are different ways that fossils can preserve. Fossils can be preserved
in rocks, tar, amber, ice, and mummification. Here's a little info on them.
Fossils in Rocks: When organisms die, the soft, fleshy parts of their
bodies decompose, leaving only the hard parts. Many times, these hard parts
get buried in sediments and are preserved while the sediment turns to rock.
Fossils in Tar: There are places where tar occurs naturally like
in California. These tar pits were around when the saber tooth was alive.
That's about 2 million years ago! The animals that get caught in the
tar sinks into it. As the years go by, the tar pit gets dried up and the
animal's body turns into only bones.
Fossils in Amber: Imagine a fly landing on a drop of tree sap. Suppose
the insect gets trapped in the sap and the sap hardens. Hardened tree
sap is called Amber. Some of our best insect fossils are found in amber.
Fossils in Ice: Suppose a woolly mammoth is walking on top of a glacier
and slips into a crack and gets trapped in the ice. The animal freezes
and gets preserved in the ice until the glacier thaws (melts) thousands
of years later.
Mummification: When organisms die in dry places like deserts, they
can sometimes dry up so fast, that there isn’t enough time for even their
soft parts to decay. This is called mummification.
Types of Fossils
Trace
Fossils: Any naturally preserved evidence of an animal’s activity. Just
like animals today, animals in the past left tracks behind. These tracks
became fossils when they filled with sediment that eventually turned to
rock. Even though the animal that left these tracks is long gone, these
tracks are evidence that these animals existed and once roamed the Earth.
Another type of a trace fossil is a burrow. Burrows are shelters
that the animals made as homes or shelters because of the weather. Like
tracks, burrows are preserved when filled with sediment and buried quickly.
Coprolites are another type of trace fossil. Coprolite actually means
“dung stone” in greek. They are preserved feces, or dung from the animal.
Coprolites can provide information about that habits and diets of the animals.
Molds and Casts
A mold is a cavity
in the ground or rock where a plant or an animal was buried. Often, the
cavity has been filled in, leaving a cast of the original organism.
A cast is an object created when the sediment fills a mold and becomes
rock. A cast shows what the outside of the organism looked like.
With all this information, you can tell that scientists used fossils
to interpret the past. By examining the fossils, scientists can figure
out what was happening in the environment when the sediments surrounding
the fossils were deposited. Scientists can also interpret how plants and
animals have changed over time by studying fossils from different parts
of the geologic column.
Top