In sedimentary rock the oldest fossils would be expected to be found
a. in the top layer of rock
b. in the middle layers of rock
c. in the bottom layer of rock
d. spread throughout all of the layers of rock

Which statements explains what the fossil records indicates? check all that apply. a) earth is 4.5 billion years old b) many organisms have become extinct c) mammals have always existed on earth d) mass extinctions have occurred several times on earth e) the amount of water on earth has decreased over time?