 As of 2008 only two in @-@ depth studies of the mix of fossils in any part of the Burgess Shale had been published , by Simon Conway Morris in 1986 and by Caron and Jackson in 2008 . Caron and Jackson commented that Conway Morris had to rely on a set of specimens that may not have been representative , since their excavators discarded specimens they found uninteresting ; and for which the exact level in the rock sequence had not been recorded , making chronological analyses impossible . Both studies noted that the set of species in Walcott 's Phyllopod Bed ( Conway Morris , 1986 ) and its expanded version the Greater Phyllopod Bed ( Caron and Jackson , 2008 ) was different from those found in other parts of the Burgess Shale ; and Conway Morris commented that faunas at most other Burgess Shale sites resembled those of the Raymond Quarry , which is above and therefore more recent than the Greater Phyllopod Bed ( abbreviated " GPB " ) . 
