Precambrian SuperEon
This major event marked the beginning of oxygen in Earth’s atmosphere
What is the Great Oxygenation Event?
The era began with this explosion of diverse life forms
What is the Cambrian Explosion?
This era is commonly known as the “Age of Reptiles"
What is the Mesozoic Era?
Fossils that form when minerals replace the remains of an organism
What are petrified fossils?
The first known life forms on Earth were these
What are prokaryotes (or bacteria)?
This armored fish was one of the dominant species during the Devonian period
What is a placoderm?
The Mesozoic is made up of these three periods
What are the Triassic, Jurassic, and Cretaceous?
This fossil type shows evidence of an organism’s activity, like footprints or burrows
What are trace fossils?
The Earth formed approximately this many years ago during the Hadean Eon
What was 4.6 billion years ago?
The largest mass extinction in Earth's history occurred at the end of this period
What is the Permian period?
This mass extinction at the end of the Cretaceous wiped out the dinosaurs
What is the Cretaceous-Paleogene (K-Pg) extinction?
These fossils are used to define and identify geologic periods
What are index fossils?
The name of the ancient supercontinent thought to have existed in the late Precambrian
What is Rodinia?
This era saw the first appearance of land plants and vertebrates
What is the Paleozoic Era?
This type of dominant plant group began to flourish in the Cretaceous
What are flowering plants (angiosperms)?
This marine organism, known for its spiral shell, is a well-known index fossil
What is an ammonite?
These microscopic, layered structures formed by cyanobacteria are some of the oldest fossils
What are stromatolites?
These two mountain-building events (orogenies) occurred during the Paleozoic in North America
What are the Appalachian and Ouachita orogenies?
These flying reptiles, often confused with dinosaurs, lived during the Mesozoic
What are pterosaurs?
This specific type of fossil preserves an organism in tree resin
What is amber?