19.1 The Fossil Record
define: geologic time scale
time line of Earth's history built by paleontologists and geologists.
Define: half-life
time required for half the radioactive samples in a sample to decay.
How long did the Neogene period last?
23-1.8 million years ago
How long did the period Triassic last?
251-200 million years ago
How long did the Permian period last?
299-251 million years ago
How long did the Caborniferous period last?
359-299 million years ago
How long did the Devonian period last?
416-359 million years ago
How long did the Silurian period last?
444-416 million years ago
How long did the Precambrian Time last?
4600-542 million years ago
How long did the Ordovician period last?
488-444 million years ago
How long did the Cambrian period last?
542-488 million years ago
How long did the Paleocene period last?
65.5-23 million years ago
What is a paleontologist?
researchers who studies fossils to learn about ancient life
Most fossils are found in layers of _____ rock
sedimentary
define: extinct
species that has died out
How long did the period Jurassic last?
200-146 million years ago
How long did the Quaternary period last?
1.8 million years ago- present
How long did the Cretaceous period last?
146-65.5 million years ago
How has planet's environment and living things affected each other to shape life history of Earth?
Building mountains, opening coastlines, changing climates, and geological forces have altered habitats of living organisms repeatedly throughout Earth's history. The actions of living organisms over time have changed conditions on the land, water and atmosphere of planet Earth.
What 3 periods are in the Mesozoic era?
Cretaceous, Jurassic, and Triassic
What is an index fossil?
Distinctive Species that lived for a short period of time but over a wide geographic range
How are divisions of time scale "divided"?
Eons are divided into eras, and eras are divided into periods.
What do fossils reveal about ancient life?
From the fossil record, paleontologists learn about structure of ancient organisms, their environment, and the ways in which they lived
How might an asteroid impact change the Earth's climate?
It depend on how violent the impact is. If the impact is very violent, it can kick enough dust and debris in the atmosphere to cause, or contribute to, worldwide extinction of organisms on land and in the water
How was the radiologic time scale established and what are it's major divisions?
It is based on relative and absolute dating. The divisions are eons, eras, and periods.
What 6 periods are in the Paleozoic era?
Permian, Carboniferous, Devonian, Silurian, Ordovician, and Cambrian
What 3 periods are in the Cenozoic era?
Quaternary, Neogene, and Paleogene
How do we date events in Earth's history?
Radiometric dating
List the two techniques paleontologists use to determine the age of fossils
Radiometric dating and relative dating
How do scientists calculate the age of a sample using radiometric dating?
Radiometric dating uses the proportion of radioactive to stable isotopes to calculate the age of a sample
What information does the fossil record provide?
The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time
What do index fossils reveal about other material found with them?
They reveal the relative ages of rock layer and their fossils
Explain the theory of plate tectonics and tell how it has affected the distribution of fossils
This is a theory that the Earth's outermost layer is divided into plates that move. The movement is called a continental drift, and has transformed life on Earth through the formation of mountain ranges, supercontients, and other geological features. So because the continent moves everything in and under the continent moves as well, including fossils
Define: radiometric dating
when radioactive isotopes decay or break down into stable isotopes at a steady rate.
