Anomalocaris lived in the Cambrian and Ordovician seas, becoming extinct approximately 472 million years ago (1). It is considered to have had a cosmopolitan distribution, meaning that it was globally distributed in appropriate marine habitats. Specimens of Anomalocaris have been discovered in a multitude of locations, including Australia, Utah, and China (2, 3, 4). One of the locations where it has been found is the Burgess Shale, a formation in British Columbia, Canada. This site is known for exceptional preservation of both soft and hard-bodied organisms, providing a wealth of information about this ancient ecosystem (5).
Most of the organisms found at the Burgess Shale Formation were benthic, or bottom-dwelling. Free-swimming organisms were rarely preserved here (6). Many of the taxa from the Burgess Shale do not belong to any known groups represented in modern times. Their dissimilarity from modern taxa often makes them difficult to classify. Specimens found here include the many-legged Hallucigenia, the hard-shelled Naroia, and Nectocaris, a particularly enigmatic taxon that may be related to modern cephalopods (7). This site is exceptional for the number of soft-bodied organisms preserved. Only 14% of genera present are shelled. Shelled organisms likely represented an even smaller proportion of the population when these organisms were alive, providing Anomalocaris with many soft-bodied potential prey (8).