annelids. Conway Morris presented a paper in 1977 that first indicated the possible chordate position but without further explanation. He and Whittington were convinced that animal was obviously a chordate, as they wrote in the Scientific American in 1979:Finally, we find among the Burgess Shale fauna one of the earliest-known invertebrate representatives of our own conspicuous corner of the animal kingdom: the chordate phylum... The chordates are represented in the Burgess Shale by the genus Pikaia and the single species P. gracilens.Conway Morris formally placed P. gracilens among the chordates in a paper in the Annual Review of Ecology and Systematics in 1979. However, there were no structural analyses such as using microscopes to confirm the chordate features. The comparative description only earned a "putative" chordate status. The chordate nature were often described with sceptical remarks for several decades. It was only in 2012, when detailed analysis was reported by Conway Morris and Jean-Bernard Caron that the chordate position became generally accepted. The fossils are found only in a restricted series of horizons in the strata exposed on Fossil Ridge, close to the Yoho National Park. From the same location, other fish-like animal fossils named Metaspriggina were discovered in 1993. Conway Morris identified the animals as another Cambrian chordate. The fossil specimens are preserved in the Smithsonian Institution and the Royal Ontario Museum. Description Pikaia has a lancelet-like body, tapering at both ends, laterally flat and lacked a well-defined head. It measures an average of about in length. Walcott recorded the longest individuals as in length. Pikaia has a pair of large, antenna-like tentacles on its head that resembles those of invertebrates such as snails. The attachment of the tentacles makes a two-lobed structure of the head. The tentacles may be comparable to those in the present-day hagfish, a jawless chordate. It has a small circular mouth that could be used to eat small food particles in a single bite. There are a series of short appendages on either side of the underside of the head just after the mouth, and their exact nature or function is unknown. The pharynx is associated with six pairs of slits with tiny filaments that could be used for respiratory apparatus. In these ways, it differs from the modern lancelets, which have distinct pharyngeal gill slits on either sides of the pharynx and are used for filter feeding. A major primitive structure of Pikaia