Paleontology Is the Study of

Q39: Eons are subdivided first into _.

Q40: Which of the following is a period

Q41: The Mesozoic era began about how many

Q42: The time before the Phanerozoic eon is

Q43: Wood from an ancient stump has a

Q45: The K-T event occurred about _ million

Q46: The term age of mammals is sometimes

Q47: Naturally occurring uranium ultimately decays to isotopes

Q48: If a rock sample contains uranium and

Q49: New material filling a mold forms a(n)