The presence of earlier chordates among the Chengjiang, including Haikouichthys and Myllokunmingia, appears to show that cuticle is not necessary for preservation, overruling the taphonomic argument, but the presence of tentacles remains intriguing, and the organism cannot be assigned conclusively, even to the vertebrate stem group. Its anatomy closely resembles the modern creature Branchiostoma. A fossil species Myoscolex ateles, discovered in 1979 from Cambrian Emu Bay shale of Kangaroo Island in South Australia, had been debated as among the oldest annelids, or at least other invertebrate groups. Polish palaeontologist Jerzy Dzik in his formal description in 2003 notes that it "closely resembles the slightly geologically younger Pikaia" in having smooth cuticle as well as muscular segmentation, and projections on its backside (ventral chaetae) that look like Pikaia's tentacles. He concluded:In fact, there is little evidence for chordate affinities of Pikaia. Its relationship with Myoscolex [as annelid in his proposition] appears a much better solution. Both were initially identified as polychaetes and this line of inference perhaps deserves confrontation with more recent evidence than that available to the authors who proposed these genera. Comprehensive description The first comprehensive description of Pikaia was published by Conway Morris and Jean-Bernard Caron in the May 2012 issue of Biological Reviews. The anatomical examination and interpretation based on 114 fossil specimens confirm the classification as a chordate. According to the new assessment, Pikaia fossils indicate important features that define the animal as a primitive chordate. All Pikaia fossils are in the range of 1.5 to 6 cm in length, with an average of 4 cm. Having a laterally compressed and fusiform (tapering at both ends) body, the exact width and height are variable, and normally its height is twice that of its width throughout it body. The head is bilaterally symmetrical with a distinct pair of tentacles. Due to its small size, only about 1 mm in diameter, the structural details are indistinguishable. Some specimens show a darker central line on the tentacles which may represent a nervous fibre; thus making the tentacles as sensory feelers. A mouth is marked by a small opening the enterior end of the gut towards the underside of the head. There are no jaws and teeth. Walcott had mentioned the presence of two large eyes, but no specimens, including Walcott's original collection, show any evidence of eyes. One of the most unusual body parts is a series of appendages