End Show Slide 1 of 40 Biology Fossils Mr. Karns.
44
End Show Slide 1 of 40 Biology Fossil Fossil s s Mr. Karns Mr. Karns
-
Upload
madyson-lucia -
Category
Documents
-
view
217 -
download
3
Transcript of End Show Slide 1 of 40 Biology Fossils Mr. Karns.
End Show
Slide 1 of 40
Biology
FossilsFossils
Mr. KarnsMr. Karns
End Show
Slide 2 of 40
17-1 The Fossil Record
End Show
17-1 The Fossil Record
Slide 3 of 40
Fossils and Ancient Life
What is the fossil record?
It is NOT an Elvis Presley record!
End Show
Slide 4 of 40
17-1 The Fossil Record Fossils and Ancient Life
Fossils and Ancient Life
Paleontologists are scientists who collect and study fossils.
All information about past life is called the fossil record.
The fossil record includes information about the structure of organisms, what they ate, what ate them, in what environment they lived, and the order in which they lived.
End Show
Slide 5 of 40
17-1 The Fossil Record Fossils and Ancient Life
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.
End Show
Slide 6 of 40
17-1 The Fossil Record Fossils and Ancient Life
The fossil record provides incomplete information about the history of life.
Over 99% of all species that have lived on Earth have become extinct, which means that the species has died out.
End Show
Slide 7 of 40
17-1 The Fossil Record How Fossils Form
How Fossils Form
Fossils can be as large as a complete, preserved animals, or as small as a fragment.
Most fossils form in sedimentary rock.
Sedimentary rock forms when exposure to the elements breaks down existing rock into small particles of sand, silt, and clay.
End Show
Slide 8 of 40
17-1 The Fossil Record How Fossils Form
Fossil FormationWater carries small rock particles to lakes and seas.
End Show
Slide 9 of 40
17-1 The Fossil Record How Fossils Form
Dead organisms are buried by layers of sediment, which forms new rock.
End Show
Slide 10 of 40
17-1 The Fossil Record How Fossils Form
The preserved remains may be later discovered and studied.
End Show
Slide 11 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Interpreting Fossil Evidence
Paleontologists determine the age of fossils using relative dating or radioactive dating.
End Show
17-1 The Fossil Record
Slide 12 of 40
Interpreting Fossil Evidence
What information do relative dating and radioactive dating provide about fossils?
End Show
Slide 13 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Relative Dating
In relative dating, the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock.
Rock layers form in order by age—the oldest on the bottom, with more recent layers on top.
Law of Horizontality- sedimentary rocks layed down horizontal, next layer on top etc.
End Show
Slide 14 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Relative Dating
End Show
Slide 15 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Index fossils are used to compare the relative ages of fossils.
An index fossil is a species that is recognizable and that existed for a short period but had a wide geographic range.
End Show
Slide 16 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Relative dating allows paleontologists to estimate a fossil's age compared with that of other fossils.
It does not give an actual age- only a relative age ….. This is older than that type thing.
End Show
Slide 17 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Radioactive Dating
Scientists use radioactive decay to assign an absolute age to rocks.
Some elements are radioactive and steadily break down into nonradioactive elements.
End Show
Slide 18 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Radioactive dating is the use of half-lives to determine the age of a sample.
A half-life is the length of time required for half of the radioactive atoms in a sample to decay.
End Show
Slide 19 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
End Show
Slide 20 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
In radioactive dating, scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.
End Show
Slide 21 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Carbon-14 begins to decay when an organism dies.
Carbon-12 is not radioactive and does not decay.
By comparing the amounts of carbon-14 and carbon-12 in a fossil, researchers can determine when the organism lived.
Carbon -14 releases particles at a know consistent rate.
End Show
Slide 22 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Carbon-14 has a useful range in dating fossils of up to about 60,000 years. It has a half life of 5,730 years.
This means that in 5,730 ½ of the C14 will be released and it will be N14.
By comparing the the ratio of C12 to C14 in a living organism and a dead one, it is possible to determine how old something is or how long agao it died.
End Show
Slide 23 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
If it is found that ½ of the C14 is present from what is found in a live organism, then 5,730 years have passed or 1 half life.
If ¼ is found, that is 2 half lives or 11,1460 years.
What if 1/16 of the C14 was found in a fossil. How many half lives would that be and how long ago did the organism die?
End Show
Slide 24 of 40
17-1 The Fossil Record Interpreting Fossil Evidence
Other radioactive isotopes are used to date older rocks and fossils.
Uranium 235 changes to Lead 207 in 700,000,000 years, so it has a useful range of over 500,000 years.
Potassium-40 changes to Argon -40 in 1.25 billion years
Uranium-23 to Lead 206 in 4.5 billlion years so it is used to date really old thiongs over 100 million years old.
* To use the wrong isotope would yield large amounts of error and is not useful or accurate.
End Show
17-1 The Fossil Record
Slide 25 of 40
Geologic Time Scale
Geologic Time Scale
What are the main divisions of the geologic time scale?
End Show
Slide 26 of 40
17-1 The Fossil Record Geologic Time Scale
Paleontologists use a scale called the geologic time scale to represent evolutionary time.
Scientists first developed the geologic time scale by studying rock layers and index fossils worldwide.
End Show
Slide 27 of 40
17-1 The Fossil Record Geologic Time Scale
The basic divisions of the geologic time scale are eras and periods.
End Show
Slide 28 of 40
17-1 The Fossil Record Geologic Time Scale
Geologic time begins with Precambrian Time, which covers about 88% of Earth’s history.
Vendian 650–544
End Show
Slide 29 of 40
17-1 The Fossil Record Geologic Time Scale
Eras
Geologists divide the time between Precambrian time and the present into three eras:
• Paleozoic Era
• Mesozoic Era
• Cenozoic Era
End Show
Slide 30 of 40
17-1 The Fossil Record Geologic Time Scale
The Paleozoic began about 544 million years ago.
Many vertebrates and invertebrates lived during this time.
End Show
Slide 31 of 40
17-1 The Fossil Record Geologic Time Scale
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
290–245
360–290
410–360
440–410
505–440
544–505
End Show
Slide 32 of 40
17-1 The Fossil Record Geologic Time Scale
The Mesozoic began about 245 million years ago.
Dinosaurs lived during this time.
Mammals began to evolve during this era.
End Show
Slide 33 of 40
17-1 The Fossil Record Geologic Time Scale
Cretaceous
Jurassic
Triassic
145–65
208–145
245–208
End Show
Slide 34 of 40
17-1 The Fossil Record Geologic Time Scale
The Cenozoic began about 65 million years ago and continues to the present.
Mammals became common during the Cenozoic.
End Show
Slide 35 of 40
17-1 The Fossil Record Geologic Time Scale
End Show
Slide 36 of 40
17-1 The Fossil Record Geologic Time Scale
Periods
Eras are subdivided into periods, which range in length from tens of millions of years to less than two million years.
Many periods are named for places around the world where geologists first discovered the rocks and fossils of that period.
End Show
17-1 The Fossil Record
Slide 37 of 40
Geologic Time Scale
Clock Model of Earth’s History
First humans
Firstprokaryotes
Cenozoic Era
Mesozoic Era
Paleozoic Era
Precambrian Time
First land plants
First multicellular organisms
Firsteukaryotes
Radiation of mammals
Accumulation of atmospheric oxygen
End Show
- or -Continue to: Click to Launch:
Slide 38 of 40
17-1
End Show
Slide 39 of 40
17-1
Which of the following statements about fossils is NOT true?
a. Most fossils form in sedimentary rock.
b. Fossils occur in a particular order.
c. Only a small portion of fossils are from extinct organisms.
d. Fossils can be used in relative dating of rock formations.
End Show
Slide 40 of 40
17-1
The fossil record consistently shows evidence that
a. all forms of life have existed in all geologic eras.
b. living organisms have only been on Earth for a short time.
c. living things have changed over time.
d. ancient life-forms are much the same as forms found living today.
End Show
Slide 41 of 40
17-1
Index fossils assist paleontologists in dating rocks because they represent species that
a. were widely distributed and existed for a very long time.
b. existed in a single location for a short period of time.
c. were widely distributed and existed for a short time.
d. existed in a single location for a very long time.
End Show
Slide 42 of 40
17-1
Determining the age of a fossil by comparing its placement with fossils in other layers of rock is called
a. carbon-14 dating.
b. fossil-indexing.
c. relative dating.
d. absolute dating.
End Show
Slide 43 of 40
17-1
According to the geologic time scale, geologic time begins with
a. Precambrian Time.
b. the Paleozoic Era.
c. the Quaternary Period.
d. the Cambrian Era.
END OF SECTION
![Karns y Mingst_Realism[1]](https://static.fdocuments.in/doc/165x107/577d1fe81a28ab4e1e9196cb/karns-y-mingstrealism1.jpg)
