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Dinosaur Fossils
In the past century, one of the most amazing findings by scientists
has been dinosaur bones. Dinosaur bones also called fossils are
the remains of old dinosaur skeletons. Sometimes scientists who
discover dinosaur fossils just find footprints in the dirt. Other times,
they find enough fossils to make a complete dinosaur. But how do
dinosaur bones that are millions of years old get turned into
fossils? How can something buried beneath dirt and sand last for
so long?
Fossil Formation
When dinosaurs or other ancient animal or plant life dies, a gradual process begins. (A) Then the dead
dinosaur is eventually covered by dirt and mud. (B) This leaves the hardest parts of the dinosaur- bones
and teeth. (C) After thousands of years, the chemicals in the buried dinosaur's body go through a series of
changes. (D) As the bone slowly decays, groundwater gets inside the bone. The minerals in the groundwater
are replaced with the chemicals in the bone. These minerals are the same as the surrounding rock. As the
dinosaur bone turns into a fossil, it becomes a heavy, rock-like version of the original dinosaur. It is now
officially called a fossil. When scientists look for dinosaur fossils, they look for specific rock types. Fossils are
usually found in either shale, siltstone, mudstone, or sandstone.
Preservation
(E) Preservation is an important word when studying fossils. (F) It means to keep something in the same
condition for a long time. (G) One of the best examples of dinosaur fossils is in the Field Museum in Chicago.
(H) The Tyrannosaurus Rex (or T-Rex) was the fiercest and largest dinosaur on the planet. It was a carnivore,
or meat eater. T-Rex liked to eat smaller dinosaurs for dinner, using its powerful jaws to crush its victims. The
skeleton of Sue was discovered in the dry plains of South Dakota in 1990 by Sue Henderson, a scientist. By
studying prehistoric fossils, we can learn about life millions of years ago.
