What is an Anomalocaris canadensis?




1892, Joseph Whiteaves


Yoho National Park – BC, Canada


Cambrian – 508 Million Years Ago


Burgess Shale Formation


1 to 3 feet



Anomalocaris canadensis: first described in 1892 by British-Canadian paleontologist Joseph Frederick Whiteaves. The most notable specimens were retrieved from the Burgess Shale in Yoho National Park, Canada. Several early paleontologists investigating the fossils mistakenly took distinct parts of the organism, (the mouth, pincers, and tail) and categorized them as three separate animals. Growing between 1 and 3 feet long, this intriguing relative of arthropods hails from the Cambrian period, about 508 million years ago. Believed to be one of the world’s first apex predators, it would have used its pineapple-shaped mouth to crush or suck unsuspecting victims into its gut. This odd yet endearing critter continues to puzzle and amaze the scientific world.




Andy the Anomalocaris


Adopt a cuddly prehistoric plush sea-bug that is educational and fun!

 Anomalocaris canadensis is the perfect candidate for Paleo Pals® plush toys, for it represents the beginning of truly complex predators. This life-sized high quality reconstruction of one the Cambrian period’s most enigmatic creatures is lovingly designed with data from original fossils.

Strange in every respect, this sea-bug inspires people of all ages to explore the science of natural history. A. canadensis’s charming weirdness makes it an intriguing and delightful companion to the infinitely curious.










The first recorded discovery of this bizarre creature dates to 1892, when British-Canadian paleontologist Joseph Frederick Whiteaves collected fossils preserved in shale (sedimentary rock composed of clay and silt) while on a prospecting trip in British Columbia. He found a small specimen that appeared to be the abdomen of a crustacean, possibly a shrimp. Whiteaves dubbed this new animal Anomalocaris canadensis, which translates to “abnormal shrimp from Canada”.


Fossils from this quarry are a mix of mineralized elements and original soft-bodied material, a very unusual type of preservation. He also collected materials of what appeared to be jellyfish, sea cucumbers, and crustaceans from the site, believing them to have no connection with anomalocaris. In 1985, this analysis was turned on its head when Harry B. Whittington and his colleague Derek Briggs found a complete fossil of A. canadensis conclusively showing that these pieces, long thought to be separate, are actually body parts of one animal, a creature unlike anything seen before. 






What does it mean to live in the Cambrian period, 541 – 485.4 million years ago? Well, it is the first point in geologic time where paleontologists are able to observe prehistoric environments in all of their complexity. As one goes further back in time, the rarer and rarer the fossils are. This is due to older rocks either crumbling with time or melting down into lava, becoming new rock. Due to these factors, prior to the Cambrian, there is little visible diversity. The sudden increase in observable life forms at this time, along with higher physical complexity in these creatures, is called the “Cambrian Explosion”. For animals, it is an age of eyes, exoskeletons, and brand new means of movement. It is also a time of experimentation, for many of the strangest creatures in history all come from this period.




A. canadensis is one of the biggest species ever found in the middle Cambrian period (about 508 million years ago) growing between 1 to 3 feet long. This amazing prehistoric animal is often so well preserved that even its digestive organs are intact. Anomalocaris, as a genus, has no comparable living relatives today, and its anatomy is so different, that to the modern eye, it is alien looking. It has a segmented body that appears to be made of soft tissue with little to no exoskeletal elements. Its segments consist of large overlapping swimming “lobes”, allowing it to undulate through the water like oars on a Viking ship. These large moving flaps are lined with small bristles, which are now believed to be gills. Unlike its body, Anomalocaris’s pineapple shaped mouth and its feeding pincers are constructed from hard tissue. This critter’s mouth is quite unusual for it opens and closes like the shutter of a camera. Long thought to be the terror of trilobites using its pointy “teeth” to crush rigid shells, new evidence suggests that its jaws are inept at breaking exoskeletons and are more useful for slurping up squishy animals, such as jellyfish, into its waiting maw. This concept is supported by the presence of downward facing prongs that follow the creature’s esophagus, allowing it to hold down struggling victims as it swallows. Its bizarre feeding “arms” are lined with fairly long spikes to help it spear passing prey. A. canadensis has an excellent sense of vision with its pair of massive compound eyes mounted on flexible stalks. Its eyes are so keen that it may have been able to see in more spectrums of light than humans. Paleontologists suspect that anomalocaridids are related to arthropods (including insects, crustaceans, and arachnids), but some of its features are so unique that this hypothesis is still being debated.






Paleo Pals® would like to thank Dr. James W. Hagadorn, the Curator of Geology at the Denver Museum of Nature and Science, for supplying scientific literature and resources to aid in the accuracy of our educational toys. We would also like to extend a thank you to the Royal Ontario Museum for their publicly available scholarly materials that helped make this project possible. Another very important organization we would like to acknowledge is the Burgess Shale Geoscience Foundation, for providing a great deal of accessible academic material.





Briggs, D. E. G., Mount, J. D., 1982, The Occurrence of the Giant Arthropod Anomalocaris in the Lower Cambrian of Southern California and the Overall Distribution of Genus, Journal of Paleontology, 56 (5): 1112–8.


Briggs, D. E. G., Robison, R. A., 1984, Exceptionally preserved nontrilobite arthropods and Anomalocaris from the Middle Cambrian of Utah, University of Kansas Paleontological Contributions, (111).


Briggs, D.E.G., Erwin, D.H., Collier, F.J., 1995, Fossils of the Burgess Shale, Washington: Smithsonian Inst Press.


Butterfield, N.J., 1990, Organic Preservation of Non-Mineralizing Organisms and the Taphonomy of the Burgess Shale, Paleobiology, Paleontological Society, 16 (3): 272–286.

Conway Morris, S., 1998, The crucible of creation: the Burgess Shale and the rise of animals, Oxford, Oxfordshire: Oxford University Press, pp. 56–9.


Daley, A. C., Bergström, J., 2012, The oral cone of Anomalocaris is not a classic peytoia, Naturwissenschaften, 99 (6): 501–504.


Daley, A. C., Paterson, J. R., Edgecombe, G. D., García-Bellido, D. C., Jago, J. B., 2013, Donoghue, P., New anatomical information on Anomalocaris from the Cambrian Emu Bay Shale of South Australia and a reassessment of its inferred predatory habits, Paleontology.


Gould, S. J., 1989, Wonderful Life: the Burgess Shale and the nature of history, New York, W.W. Norton, pp. 194–206.


Gould, S. J., Conway Morris, S., Debating the significance of the Burgess Shale: Simon Conway Morris and Stephen Jay Gould, Showdown on the Burgess Shale, Natural History magazine, 107 (10): 48–55.


Hagadorn, J. W., 2009, Taking a Bite out of Anomalocaris, Smith, M. R., O’Brien, L. J., Caron, J. B., Abstract Volume, International Conference on the Cambrian Explosion (Walcott 2009), Toronto, Ontario, Canada: The Burgess Shale Consortium.


Paterson, J. R., García-Bellido, D. C., Lee, M. S. Y., Brock, G., A., Jago, J. B., Edgecombe, G. D., 2011, Acute vision in the giant Cambrian predator Anomalocaris and the origin of compound eyes.


Lexicon of Canadian Geological Units, Burgess Shale, (accessed may 2015).


Salleh, A., 2011, Cambrian predator had killer eyes, ABC Science: (accessed May 2015).


Usami, Y., 2006, Theoretical study on the body form and swimming pattern of Anomalocaris based on hydrodynamic simulation, Journal of Theoretical Biology, 238 (1): 11–7.


Whittington, H. B., Briggs, D. E. G., 1985, The Largest Cambrian Animal, Anomalocaris, Burgess Shale, British Columbia, Philosophical Transactions of the Royal Society, B 309 (1141): 569–609.