Year 1: Discovering Earth Science

Essay on fossils:

"Trilobites were an early group of arthropods found throughout the prehistoric world. Living in large groups these “pill bug” like water dwellers were found in shallow water and reefs. The trilobite is named such because it’s body is divided into three lobes and three sections. Despite the hard shell over all three sections they were very flexible. These Trilobita were able to walk, swim and could even roll up in defense.

First appearing in the fossil record during the Cambrian era (542 mya) they spread quickly. By the time they went extinct during “The Great Extinction” of the late Permian they had become a family of 150, divided into 9 orders with more than 5,000 genera. The trilobite managed to live for more than 300 million years and inhabited what would become all eight continents and the oceans in between.

Although these creatures died out more than 200 million years ago they remain to this day one of the most important prehistoric animals. One of their most significant features is their compound eye. They were the first creature on Earth to evolve such a feature. They also featured a mineralized exoskeleton and gills. And they are by far the most diverse group of extinct organisms with more than 15,000 different species with more being discovered every passing year. Because of this diversity and their longevity throughout prehistoric time they play a very important roll in determining the history of different geological areas.

Trilobites are one of the most popular fossils for both the professional and amateur collectors of modern times. Their shells and impressions of their bodies can be found around the world. The most reliable sources of these fossils lie in parts of Russia, Spain and Lower Asia. Popular locations within the United States include Utah and Okalahoma. The largest fossil, thus far, was found by Canadian paleontologists in Manitoba. This find placed the largest known trilobite fossil size to over 70cm (2.3 ft) long."


References

Busey, Coenraads, Willis & Roots, The Nature Company Guides: Rocks & Fossils, The Nature Company, 1996, San Francisco.

http://www.trilobites.info/#faq

http://www.manitobamuseum.mb.ca/mu_trilobite.html

Tuesday, September 05, 2006