 Conway Morris found that the shelly fossils in Walcott 's Phyllopod Bed were about as abundant as in other shelly fossil deposits , but accounted for only 14 % of the Phyllopod Bed fossils . Assuming that , as in modern marine ecosystems , about 70 % of the species that lived in the Early Cambrian seas are unsuitable for fossilization , he estimated that the shelly fossils probably represent about 2 % of the animals that were alive at the time . Since these shelly fossils are found in other parts of North America and , in many cases , over a much wider range , the Burgess Shale fossils , including the soft @-@ bodied ones , probably show how much diversity could be expected at other sites if Burgess Shale type preservation were found there . 
