page_title: Fossils of the Burgess Shale
section_title: Soft-bodied fossils
hierarchical_section_title: Fossils of the Burgess Shale / Notable fossils / Soft-bodied fossils
caption_attribution_description: English: Size comparison of selected Burgess Shale fauna and a human. Modified from illustrations by ArthurWeasley, Matt Martyniuk, and Mateus Zica Species, from top to bottom: Anomalocaris canadensis Laggania cambria Opabinia regalis Wiwaxia corrugata Pikaia gracilens Hallucigenia sparsa
context_page_description: The fossils of the Burgess Shale, like the Burgess Shale itself, formed around 505 million years ago in the Mid Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 60,000 specimens in a series of field trips up from 1909 to 1924. After a period of neglect from the 1930s to the early 1960s, new excavations and re-examinations of Walcott's collection continue to discover new species, and statistical analysis suggests discoveries will continue for the foreseeable future. Stephen Jay Gould's book Wonderful Life describes the history of discovery up to the early 1980s, although his analysis of the implications for evolution has been contested.
  The fossil beds are in a series of shale layers, averaging 30 millimetres and totalling about 160 metres in thickness. These layers were deposited against the face of a high undersea limestone cliff. All these features were later raised up 2,500 metres above current sea level during the creation of the Rocky Mountains.
context_section_description: Caron and Jackson's survey covered 172 species found in the Greater Phyllopod Bed. The list below concentrates on recent discoveries and on species that have been central to major scientific debates.
  Marrella was the first Burgess Shale fossil that Whittington re-examined, and gave the first indication that surprises were on the way. Although clearly an arthropod that walked on the sea-floor, Marella was very different from the known marine arthropod groups (trilobites, crustaceans and chelicerates) in the structure of its legs and gills, and above all in the number and positions of the appendages on its head, which are the main feature used to classify arthropods. A fossil of Marrella from the Burgess Shale has also provided the earliest clear evidence of molting.
  Whittington's first presentation about Opabinia made the audience laugh. The reconstruction showed a soft-bodied animal with a slim, segmented body; a pair of flap-like appendages on each segment with gills above the flaps; five stalked eyes; a backward-facing mouth under the head; and a long, flexible, hose-like proboscis that extended from under the front of the head and ended in a "claw" fringed with spines. Whittington concluded that it did not fit into any phylum known in the mid-1970s. Opabinia was one of the main reasons why Stephen Jay Gould in his book Wonderful Life considered that Early Cambrian life was much more diverse and "experimental" than any later set of animals, and that the Cambrian explosion was a truly dramatic event, possibly driven by unusual evolutionary mechanisms. He regarded Opabinia as so important to understanding this phenomenon that he originally wanted call his book Homage to Opabinia. However subsequent research has concluded that Opabinia is closely related to the arthropods and possibly even closer to ancestors of the arthropods. 
  The discovery of Anomalocaris ("abnormal shrimp") was a comedy of errors. The name was initially given to a fossil that looked like the rear end of a shrimp-like crustacean. Walcott classified a ring-like fossil he called Peytoia as a kind of jellyfish, and another poorly preserved fossil he called Laggania as a holothurian (sea cucumber). After many plot twists, Derek Briggs started dissecting another ill-defined fossil in very thin slices and found a pair of Anomalocaris-like structures on one end of a specimen of Laggania, which also had a specimen of Peytoia attached just behind those of Anomalocaris. After dissecting more specimens and finding similar configurations, Briggs and Whittington concluded that the whole assemblage represented a single animal, which was named Anomalocaris because that was the earliest name assigned to any of its parts. This animal's body was fragile and usually disintegrated before it could be fossilized. But the complete animal had tough grasping appendages (Anomalocaris), a tough, ring-like mouth with teeth on the inner edge (Peytoia) and a long, segmented body (Laggania) with flaps on the sides that enabled it to swim with a Mexican wave motion, and perhaps to turn quickly by putting the flaps on one side into reverse. This monster was over 2 feet (0.61 m) long when other animals were only a few inches at most. Nedin suggested in 1999 that the animal was capable of taking heavily armored trilobites apart, possibly by grabbing one end of their prey in their jaws while using their appendages to quickly rock the other end of the animal back and forth, causing the prey's exoskeleton to rupture and allowing the predator to access its innards. In 2009 Hagadorn found that anomalocarid mouthparts showed little wear, which suggests they did not come into regular contact with mineralised trilobite shells. Computer modeling of the Anomalocaris mouthparts suggests they were in fact better suited to sucking on smaller, soft-bodied organisms. Although Whittington and Briggs concluded that Anomalocaris did not fit into any known phylum, research since the 1990s has concluded that it was closely related to Opabinia and to the ancestors of arthropods. In 2009 a fossil named Schin
caption: Reconstruction of a large Anomalocaris (   ), with a human leg and various Burgess Shale animals to show its size
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