    Seritence Which ‘priticiple is based dn the  appeararidPof fossils in Sedimentary rocks?    senteded 2egrhe. pithciple becdimes. quite  complex, however, giveri the“ uneertaintie’s-of  fossilization, “the~ localization ‘of fossil types  due- to lateral, “changes ’,in- habitat (facies  change in sedimentary strata), ‘aiid that notall  fossils'thay be found globally at the same time.         