Earths History Flashcards
how old is the earth
4.6 billion years old
what happened 3.9 billion years ago
the earth cooled and water condenses and fills oceans
when was the precambrian era
4.6BYA - 544 MYA
how many years ago do eukaryotic organisms appear
1.8 BYA
when was the Paleozoic era
544 MYA - 245 MYA
what happend during the first half of the paleozoic era
animals with backbones appear in the ocean and seeded plants appear on land
what happened in the middle of the paleozoic
4 legged amphibians are on land
what happened at the end of the paleozoic
reptiles begin to flourish on land
when was the mesozoic era
245 MYA - 66 MYA
what was the mesozoic famous for
dinosaurs and appearance of small mammals
which era had the theorized meteorite that killed the dinosaurs
mesozoic era
when was the cenozoic era
modern era
when did the first primates appear
30 MYA during the tertiary period
when did modern humans begin to appear
200,000 YA during the quaternary period
what are fossils
any trace or remainds of an organisms that has been preserved by natural processes
what are fossils used to determine
geography, environment, animals, plants, and behavior
where are fossils found
sedimentary rock
what is a trace fossil
marking left by an animal like a footprint
what is a cast fossil
fossil in which mineral fill a space left by a decayed organism
what is an imprint fossil
when a thin object falls into sediment and leaves mark when rock hardens
what is a petrified fossil
when minerals penetrate and replace hard parts of an organism
what are mold fossils
when organisms is buried in sediment and decays leaving an empty space
what is an amber or ice fossil
when the entire organisms is trapped in tree sap or ice
which layers are the oldest
the bottom layrs
fossil dating can determine _______ of appearance and extinction
order
what does radiometric fossil dating use
radioactive isotopes to date fossils
how is appropriate age determined
by comparing the isotope to th eelement it decays into
what is teh halflife of K-40
13 billion years
what is the halflife of carbon 14
5730 years
