The Fossil Record Flashcards
Relative dating
Determining the relative age of fossils without determining their precise age, by knowing one fossil is older than another by how much lower if is in the rich layers
Fossil
Evidence of an organism from the past, must be atleast 10,000 years old
Radiometric dating
Using the known decay rate of certain isotopes (like Carbon 14) to determine the age of rocks and thus the age of fossils in the rocks
Half time
The time required for half of a sample of isotope to decay
Plate tectonics
Theory that explains how the large blocks of earths crust move around
Geological time scale
A system of measurement to describe the history of earth
Precambrian
Oldest era, (earth formed, made up of single celled organisms, oldest fossils of prokaryote and eukaryotics) 4.6 bya -540 mya
Paleozoic
Era after Precambrian, 540- 245 mya, begins with explosive radiation of life and ends with mass extinction event that ends with the formation of the supercontinent Pangea. (Plants appear and first fish and sharks)
Mesozoic
After Paleozoic, 245-65 mya, begins with an explosive radiation of new life forms and ends with mass extinction of a meteor impact. ( first mammals, dinosaurs, birds, and flowering plants appear)
Cenozoic
Most recent era, 65 mya- now, begins with an explosive radiation of new life forms (birds and mammals) and is still going, ( monkeys and humans appear, climate is tropical, Ice age happens)
Mass extinction
An event in the fossil record where a large majority of the species present go extinct and are not seen in the fossil record again
Explosive radiation/ adaptive radiation
An event in the fossil record in which a large number of new species or forms appears in the fossil record in a very short period of time
Bya
Billion years ago
Mya
Million years ago
Pangaea
A large continent formed at the end of the Paleozoic that is made up of all modern continents
