Skeletons!

Drawing by Ben Cranshaw

The skeletons issue Dragonfly has an article describing a dinosaur dig. The author of the article, Rodolfo Coria, is a paleontologist. If you like old stuff and animals, you can become a paleontologist just like Rodolfo! Rodolfo searches for dinosaurs in Patagonia, which is located in southern Argentina in South America.


This is where Rodolfo lives.

He found the biggest carnivorous (meat-eating) dinosaur ever known! It's named Giganotosaurus and is about a half meter longer than Tyrannosaurus rex! T. rex is estimated to have weighed about 6 tons (about 5 metric tons), while Giganotosaurus probably weighed eight to nine tons (about 7 to 8 metric tons)!!

A paleontologist is a scientist who studies fossils. Fossils are the remains, impressions, or traces of organisms preserved in rock. They can be shells, bones, prints of leaves, and even tracks of animals. Fossils tell the story of the earth. They show what animals and plants lived a long time ago as well as how the ones that are around today developed. They tell us how the temperature of the earth has gotten warmer and cooler throughout time and even how the continents and seas moved!

Unfortunately, the fossil story isn't complete because not everything that dies becomes a fossil. The organism's remains can be destroyed by erosion - wind and water that wear away the earth's surface as well as things on the surface. Organisms can also decay as little organisms called bacteria feed on them.

Luckily, this doesn't always happen, and fossils form!

An imprint fossil forms when an object is pressed into mud, such as a leaf or insect. As it slowly dissolves, the mud surrounding it can harden and a space is left. A mold of the original object is formed, which fills with sediment and becomes a fossil.

This is an example of an imprint fossil.

Footprints can be imprint fossils too!

Fossils can also form when an object, such as a dinosaur bone, is buried underground for a very long time. Water can deposit minerals in the tiny spaces in the bone, called pores, and it turns into rock. This is known as petrification. Another way bones turn to rock is called replacement. Here, minerals in the actual bone (rather than the pores) are exchanged for the minerals in water.

Here is a petrified bone!

Where do fossils form?

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