Ammonite

Ammonite

Ammonite Ashtray/Candy Dish

Ammonite Pair

ammonites

Dinosaur Bone

Dinosaur egg

Dinosaur Egg

Fossil Candy Dish

Fossil Plaque

Fossil Plaque

Fossil Trinket Box

Goniatite

Keichousaurus hui

Knightia

Petrified Tree Fern

Petrified Wood

Petrified Wood

Petrified Wood

Petrified wood

Fossils are the remains of (or evidence of) plants, trees, or animals from prehistoric times. There are 4 fossil types:

1. Mold Fossil: a fossilized impression (negative image of the organism)
2. Cast Fossil:  formed when a mold is filled in (a duplication of the original)
3. Trace Fossils:   records the evidence of , or behavior of the organism  It is not formed from the organism itself. Examples include:  footprints, burrows, gastroliths, coprolite (dung) and eggs.
4. True Form fossils: A mineralized remnant or unaltered preservation of the actual plant or animal ( ex. insect in amber, dinosaur bone or petrified wood).

There are a number of different ways an organism can turn into a fossil.  The first way involves mineral rich ground water seeping through the mud or lava the organism is buried in. The minerals then get carried into spaces or pores of the buried bone or organism (permineralization).  Alternatively, acid in the ground water can dissolve the original tree or organism (sometimes cell by cell) which then gets replaced by minerals in the ground water (replacement).  Either way, a highly detailed image can be left behind.  Most petrified wood is formed by a combination of replacement and permineralization.  In some instances, the organism gets squeezed between layers of sediment.  The liquid and gas components of the organism get forced or squeezed out leaving behind a film of carbon (e.g. fossil ferns) or part of the organism itself (e.g. some fossil fish)