Ammonites are treasured by collectors.
Ammonites are the fossilized remains of mollusks which appeared on earth for about 330 million years and became extinct by the end of the Cretaceous period. Collectors treasure the fossils for the intricate shell patterns and colors.
Distribution
Ammonite fossils can be found on every continent, and in every color. Their closest living relative is the chambered nautilus, which is found in the Indian and Pacific oceans, according to the Canada Fossils website.
Name
Ammonites received their name because of their resemblance to a ram's horn, symbol of the Egyptian god Ammon. Native Americans called them buffalo stones and believed they brought good fortune. Some in England called them snake stones, believing them to have been turned to stone by saints.
Size
Early ammonites (until the middle Jurassic) usually measured less than 9 inches. Ammonites from the upper Jurassic to the lower Cretaceous period were larger, with some having a diameter of over 2 feet.
Patterns
There are three basic patterns found on the ammonite's septa, or walls dividing the chambers of the shell: goniatite (irregular zigzags), ceratite (regular waves) and ammonite (having a feathery or fern-like appearance).
Index Fossil
The hard shell of the ammonite was easily fossilized, and an abundance from several different geologic time periods have survived. These factors make it a useful index fossil, a way for paleontologists and geologists to determine the age of rock layers, according to the Fossil Facts and Finds website.
Tags: called them, Cretaceous period
