Fossils

Fossils

1. shows

   • succession of organisms
   • extinct organisms were different from organisms that exist today
   • as new species arise, others become extinct

2. problems

   • incomplete
   • organism had to die at right place and time for burial conditions to favor fossilization
   • rock layer containing fossil had to escape geologic processes that destroy or severely distort rocks
   • chance that someone will find a fossil is remote
   • fossil record is slanted in favor of species that
     • have existed for a long time
     • were abundant
     • widespread
     • had hard shells or skeletons