By: Colby Lacks
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Without such fossils, scientists would know
very little about the history of life on earth.
The answers we get from rocks often cause us
to ask more questions!
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Fossils are in all types of rocks.
When organisms die, the soft, fleshy parts of
their bodies decompose, leaving only the hard
parts.
There are such things as Fossils in Amber,
Frozen fossils, and Fossils in Tar.
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Fossils are the remains or traces of plants and
animals that have been preserved in
sedimentary rock.
Fossils have given us enormous amounts of
information about ancient life-forms and how
they in the oceans.
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Most fossils come from animals that lived in
the oceans.
The fossils some rocks contain also provide
clues about life-forms that lived billions of
years ago, long before dinosaurs walked the
earth.
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Fossils (from Latin fossus, literally "having been dug
up") are the preserved remains or traces of animals,
plants, and other organisms from the remote past. The
totality of fossils, both discovered and undiscovered,
and their placement in fossiliferous (fossil-containing)
rock formations and sedimentary layers (strata) is
known as the fossil record. The study of fossils across
geological time, how they were formed, and the
evolutionary relationships between taxa (phylogeny)
are some of the most important functions of the science
of paleontology. Such a preserved specimen is called a
"fossil" if it is older than some minimum age, most
often the arbitrary date of 10,000 years ago.[1] Hence
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Scientists have found dinosaur fossils on every
continent. Most of these sites are in the United
States and Europe.
Scientists dig very carefully using chisels to free
the fossils from the rock they are trapped in.
They take lots of notes to describe the fossils and
where they are found. Then they take the bones
to a laboratory and analyze them. They try to put
the bones back together like a puzzle. Sometimes
this part is easy, other times it's very difficult.
Once they know how the bones fit together, a
scientific artist sketches the bones and adds
muscles and skin.
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Most fossils are heavy and look like rocks.
They’re also a light brown or dark white
color.
Their shapes are different, however. Fossils
are shaped like whatever the original objects
were. Some are shaped like leaves, some are
shaped like paw prints, some are shaped like
bones. Fossils’ sizes are also different for the
same reason. Some fossils belonged to large
dinosaurs. Others belonged to tiny insects.
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When an animal or plant dies, usually the remains
are eaten or decompose. On occasion though, they
get buried by mud or sediment, and in the right
conditions, they harden into fossils.
The bones or original material decay, and water or
other things seep into the impression left by the
original material. This water and minerals continue
to dissolve the original material, replacing it, and
then they harden over time.
Once the fossil is formed, it’s usually heavy and feels
more like a rock. It’s also colored like a rock because
that’s what it really is! It just has a shape of
something that was alive a long time ago, and that’s
what makes it a fossil.
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Animal fossils are often bones that have been
turned to rock. Sometimes part of the flesh is
preserved, but most of the time only skeletons
remain. Because of this, it is more difficult to
find fossils of invertebrates. (Invertebrates are
animals that don’t have bones.)
We have discovered several types of animal
fossils, including bones, skin, teeth, claws, eggs,
nests, muscles, and organs.
We have also found lots of fossils of footprints,
which tell us how much animals and dinosaurs
weighed and how they might have walked.
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Insect fossils form in the same way as normal
fossils, but the exoskeleton is usually the only
thing that is left. One special type of insect
fossil is when it is preserved in
amber. Amber is tree sap that oozed over and
covered the insect, then hardened.