Since he was as old as he
could remember Jacob dreamed of becoming a paleontologist.
His interest was sparked at the age of three when he found what
appeared to be just an ordinary stone in his neighbor's
backyard. That ordinary gray stone was instead a fossil.
How did Jacob know it was a
fossil? His father had taken him to the library and this is
how it all began.
Today Jacob is giving a
presentation to his science class about five types of
fossils. He explains that most
fossils are found in sedimentary rock. The class has studied
the different types of rocks and know that sedimentary rock is
made up of mud, sand, and decayed bits of plants and animals that
settle to the bottom of oceans or lakes. Jacob explains that
fossils form within rock in several ways. Dead animals and
plants rot away and leave a hollow space in the rock. The
space is the same shape as the plant or animal that was once
alive. This he told the class is called a mold fossil.
If the mold fills with water, minerals from the water build up and
form the shape of the animal or plant. This is called cast
fossil. Petrified wood is another kind of fossil. It
is created when minerals slowly replace the cells of the dead
plant or animal. A rocklike fossil that looks very much like
the live plant or animal is formed - petrified wood. Trace
fossils are just that, he explained to his classmates.
Footprints or trails of animals that have been preserved in
rock. The last kind of fossil he shared with his classmates
was the true-form fossil. The true-form fossil is created
when the remains of animals, like bones, teeth, and shells are
As Jacob finished his fossil
presentation he found himself surrounded by eager and impatient
classmates. They all had questions for him about his
interest in paleontology, the study of prehistoric life through