Produced by the Population Genetics and Evolution class, Furman University

The Cambrian: Anomalocaris
Anomalocaris canadensis was a superpredator found during the Cambrian period. They grew to about 60cm, although some specimens have been found that were over a meter long! It had large appendages near its front that it used for capturing and grasping prey. Its mouth was located under its body and was lined with sharp teeth. It had a series of lateral lobes used for swimming, and large eyes to spot prey. The fossils of Anomalocaris are one of the most prevalent fossils of the Burgess Shale Formation in Canada. Specimens have also been found in China, Greenland, and Utah. The first specimens were found in separate parts that were classified as different species. The appendages in the front were thought to be crustaceans, the mouth was thought to be a jellyfish, and the body was thought to be a sponge (Kazlev 1999). There is still some debate over what phylum Anomalocaris should be classified under. Many classify it as an arthropod because of its jointed body. However, the classification of an aschelminth (pseudocoelomate worm) could be justified because of its asymmetrical mouth (Kazlev 1999). Many classify it with Opabinia as a "Lobopod", a stem group of animals that may have given rise to a number of modern phyla, including the Arthropoda. Anomalocaris canadensis was an important part of the Cambrian fauna. As an abundant top predator, it might have put evolutionary pressure on other organisms like trilobites, that evolved eyes on their dorsal surface (Kazlev 1999).

Page by Laura Snyder
Anomalocaris. Picture from: Ediacara.org

Kazlev MA. 2002.Anomalocaris: Cambrian super-predator. www.paleos.com. Accessed Feb 2, 2010.

Smithsonian Institution. 2010. Burgess Shale: Anomalocaris canadensis (proto-arthropod). Accessed Feb 2, 2010.