Test review trip through earths history

Fossils usually occur in

The evolution of photosynthetic organisms about 2.5 billion years ago led to

A fossil is

 fossils of organisms that were widely distributed & only lived during short period of time are

_______is a gap in the geologic record where some rock layers have been lost because of erosion

A type of organism that no longer exists on Earth is said to be

_______can provide clues about the activities of ancient organisms.

Plant leaves may form a fossil called a(an) __________________ a thin layer of carbon on rock.

The present day is part of the _________________________Era.

A fossil formed when minerals replace all or part of an organism is called

 process by which all the different kind of living things have changed over long period of time

The relative age of a rock is

The geologic timescale is a record of

Many scientists hypothesize that the dinosaurs became extinct because

The earliest life forms were

A_______fossil forms when dissolved minerals replace the remains of an organism and hardens

On the geologic timescale, the _______Era is divided into the Triassic, Jurassic periods.

The Paleozoic,Mesozoic, and Cenozoic are divisions in the geologic time scale called

How do most fossils form?

time it takes for one half of the atoms of a radioactive element to decay is called

Radioactive dating enables geologists to determine

The law of superposition states that, in horizontal layers of sedimentary rock, each layer is

The first vertebrates were

The end of the Paleozoic was marked by the