Title: Fossils
1Fossils The Geologic Time Scale
2Anticipation Guide
- If you agree with the statement, put an v beside
it. If you disagree with the statement, put an X
beside it. - ____ 1. Fossils show how plants and animals have
changed over time. - _____2. It is rare for the soft parts of an
organism to become a fossil. - ____ 3. A footprint is an example of a trace
fossil. - ____ 4. A petrified fossil is an animal that
was scared just before it died.
3Fossils
- Preserved remains or traces of an organism that
lived in the past.
- Fossils are formed when organisms die and are
buried in sediment. Eventually the sediment
builds up and hardens to become sedimentary rock. - Sediments are pieces of solid material that have
been deposited on Earths surface by wind, ice,
gravity, or chemical precipitation. - Paleontologist-scientist who study the remains of
organisms in the rock record.
4Kinds of fossils
- Petrified - when minerals replace the remains and
they become rock things like wood. - Mold - when the shell remains and the contents
dissolve (hollow) like in art class you use a
mold to get the correct shape of a bowl. - Cast - when the mold becomes filled with minerals
that are not a part of the original organism. - Index- a fossil found in a narrow time range but
widely distributed around the earthused to date
rock layers. - Trace fossil-a fossilized mark that is formed in
soft sediment by the movement or actions of an
animal.
5PETRIFIED MOLD
CAST
6- Sometimes whole animals become preserved intact,
but this is very rare. If an organism is
surrounded by ice or tar they might be discovered
looking much the same as they did when they died.
AETOSAUR FOUND IN THE NATIONAL PETRIFIED FOREST
7Relative Dating
- Relative dating looks at where the fossil is
located to determine its age relative to other
fossils. This only works if the area has been
undisturbed.
8Absolute Dating
- Uses radioactive elements near the fossils to
determine the actual age of the fossils.
- By determining the age of the radioactive
element, scientists can calculate the age of the
fossil buried nearby.
The absolute age of fossils is estimated by
dating associated igneous rock and lava flows.
9Fossil Record
- The dating of all fossils is included in the
Geological Time Scale. This scale divides the
time that the earth has existed into 4 eras. - Eras are then divided into periods based on
common events in that time period.
10Anticipation Guide
If you agree with the statement, put an v beside
it. If you disagree with the statement, put an X
beside it. ____ 1. An epoch is larger
than a period. ____ 2. Periods are the
largest division of geologic
time. ____ 3. The smallest period of
geologic time is the era. ____ 4. Fossils
and rock layers on different continents
are similar.
Anticipation Guide
11Vocabulary
- Copy the definitions below in your notebook on
your definitions page. - geologic time scale a model scientists use to
describe the timing of events and the
relationships between those events in earths
history. - era one of three long periods of geologic time
from Precambrian to the present. - period geologic time periods that eras are
divided into. - 4. epoch a division of geologic time a
subdivision of a period.
12Pre-Cambrian
- Began with the formation of the Earth 4.6 billion
years ago. - Bacteria appeared 3.5 billion years ago, followed
by algae and fungi.
13Paleozoic Era
- Divided into 5 periods
- Cambrian period - Sponges, snails, clams and
worms evolve - Ordovician period - First fishes evolved and
other species become extinct - Silurian period - Land plants, insects and
spiders appear
14- Devonian period - Amphibians evolve and
cone-bearing plants start to appear. - Carboniferous period - Tropical forests appear
and reptiles evolve. - Permian period - Seed plants become common and
insects and reptiles become widespread. Sea
animals and some amphibians begin to disappear.
15Mesozoic Era
- Divided into 3 periods
- Triassic period - Turtles and crocodiles evolve
and dinosaurs appear. - Jurassic period - Large dinosaurs roam the world.
First mammals and birds appear. - Cretaceous period - Flowering plants appear,
mammals become more common, dinosaurs - become extinct.
16Cenozoic Era
- Divided into 2 periods
- Tertiary period - First primates appear and
flowering plants become the most common. - Quaternary period - Humans evolve and large
mammals like woolly mammoths become extinct.
17- ASSIGNMENT
- Read back through the notes you have just taken.
Design 4 multiple choice questions about the
content. -
- Design one question which asks for a description
or explanation with details.