Fossil Types
The preserved remains or traces of an organism.
What is a fossil.
The age of a rock compared to other rocks.
What is relative age.
An event in which many types of living things become extinct at the same time.
What is a mass extinction.
A record of the life forms and geologic events in Earth's history.
What is the geologic time scale.
The extinction of dinosaurs gave warm-blooded vertebrates called ___________ a chance to become abundant.
What are mammals.
A hollow imprint that shows the shape of an organism.
What is a mold.
Useful fossils that help to tell the relative ages of the rocks around them.
What are index fossils.
The end of one era and the beginning of a new era is usually caused by a ________ _______________ .
What is a mass extinction.
Scientists hypothesize that Earth formed at the same time as the other planets and the sun, roughly _________ billion years ago.
What is 4.6
What are the best types of rocks for radioactive dating?
What are igneous rocks.
An example of this type of fossil would be footprints.
What is a trace fossil.
An intrusion in always _________ than the rocks around it.
What is younger.
The subdivisions of eras are called ______________ .
What is periods.
Reptiles, such as dinosaurs, were so successful during the _______________ Era that the time is often called the age of Reptiles.
What is Mesozoic.
A fossil formed when minerals replace all or part of an organism.
What is a petfrified fossil.
The method used to determine the absolute age of rocks.
What is radioactive dating.
What do most scientists think caused the mass extinction at the end of the Cretaceous Period?
What is an object from space struck Earth.
Jawless fish were earth's first ______________, or animals with backbones.
What are vertebrates.
The state fossil of New York.
What is a trilobite.
Explain how the Law of Superposition is used to determine the relative ages of sedimentary rock layers.
What is the oldest layer is that the bottom, and each higher layer is younger than the rocks below it.
Earth's atmosphere, oceans, and continents began to form during the first several hundred millions years of ______________ .
What is Precambrian Time.
Certain ammonites are used an __________ ___________ because they lived in many different areas but only for a brief time.
What are index fossils.