A useful index fossil must
be distinctive or easily recognizable, abundant, and have a wide geographic distribution and a short range through time
. Index fossils are the basis for defining boundaries in the geologic time scale
What are the characteristics of an index fossil quizlet?
Characteristics of index fossils:
Easily recognizable, short lived (found only in a few layers of rock worldwide), wide distribution (geographic range)
. A key example of an index fossil; a group of hard-shelled animals whose bodies had three sections, lived in shallow seas, and became extinct about 245mm years ago.
What are the 4 characteristics of a good index fossil?
A good index fossil is one with four characteristics:
it is distinctive, widespread, abundant, and limited in geologic time
. Because most fossil-bearing rocks formed in the ocean, the major index fossils are marine organisms. That being said, certain land organisms are useful in young rocks and specific regions.
How do you identify an index fossil?
To be considered an index fossil, it must meet 3 criteria:
The fossilized organism must be easily recognizable
. It must be easy to ID and look unique. 2. The fossils have to be geographically widespread, or found over large areas so that we can use them to match layers separated by huge distances.
What is one example of an index fossil?
Examples of index fossils include:
Ammonites
were common during the Mesozoic Era (245 to 65 mya), They were not found after the Cretaceous period, as they went extinct during the K-T extinction (65 mya).
What characteristics make up a good index fossil?
A useful index fossil must be
distinctive or easily recognizable, abundant, and have a wide geographic distribution and a short range through time
. Index fossils are the basis for defining boundaries in the geologic time scale and for the correlation of strata.
Will humans be a good index fossil?
Some fossils are more useful than others in establishing the age of rocks. These are called index fossils. …
It is possible that humans also will be good index fossils at some time in the distant future
. Humans have distinct hard parts, and we often bury our dead.
What four characteristics are best for an index fossil to have quizlet?
The four main characteristics that make a fossil a good index fossil are that
the fossil is abundant, widespread, distintive and it has to be limited in geologic time
.
What is an index fossil and how is it used?
Keyed to the relative time scale are examples of index fossils, the forms of life which existed during limited periods of geologic time and thus are used as
guides to the age of the rocks in which they are preserved
.
Which of the following is an essential characteristic of an index fossil quizlet?
Which of the following is an essential characteristic of an index fossil?
The organism lived for a very limited period of geologic time
. Sedimentary layers can be important indicators of past environmental conditions that existed when the sediments were deposited.
Which index fossil is the oldest?
The law of superposition states that each
rock
layer is older than the one above it. So, the relative age of the rock or fossil in the rock or fossil in the rock is older if it is farther down in the rock layers.
Which fossil would be the best index fossil?
Trilobites
serve as good index fossils, letting geologists date the age of the rocks that they are in.
What are the types of fossils?
There are two types of fossils-
the body fossils and the trace fossils
. Body fossils include preserved remains of an organism (i.e. freezing, drying, petrification, permineralization, bacteria and algea).
What is a bad index fossil?
Fossils that contain a lot of soft parts, single species that lived for long periods of time,were
endemic to a specific region or are rare in the field today
are criteria for being a poor index fossil that should not be used.
Which of the following is an important index fossil?
Graptolites
are important index fossils in the Silurian and Ordovician age. Ammonites are important index fossils for the Jurassic and Cretaceous era. Previously, especially macro fossils such as ammonites and graptolites were used. Nowadays, especially micro fossils such as conodonts and foraminifera are used.
How do we use index fossils?
Index fossils are
used to define geological periods
. These fossils can be defined as “commonly found, widely distributed fossils that are limited in time span.” If one finds an index fossil in a given layer, then one has bounds on the age of the layer. Using index fossils, the geological periods are defined.
