Index Fossils Directed Reading and Review

(pg 216) Fossils that are found only in the rock layers of a particular geologic period are called

• trace fossils.

• index fossils.

• carbon films.

• complete fossils.

PG 216: Which of the following are characteristics of index fossils?

• it must be present in rocks scattered over a large region.

• it must have features that clearly distinguish it from other fossils

• the organisms from which the fossil formed must have lived during a short span of geologic time.

• the fossil must occur in fairly large numbers within the rock layers.

PG 216: The organisms that form index fossils lived

• during a short span of geologic time.

• during a long span of geologic time.

• for about 200 million years.

• over any span of geologic time, long or short.

PG 216: How commonly distributed must the fossil of an organism be in order to be considered an index fossil?

• The fossil must be rare and unique.

• The fossil must occur in fairly large numbers within the rock layers such that it can be commonly found.

• The fossil may exist in any numbers, but it must be found within many different layers of rock.

• The fossil must occur in small numbers in a very specific location.

PG 216: Scientists use index fossils to...

• estimate the relative ages of different rock layers.

• find dividing points in the fossil record.

• determine branches in the development of species.

• estimate absolute ages of specific rock layers.

PG 216: Rock layers in which index fossils have been found can be dated accurately because the organisms that formed the index fossils lived...

• for a long span of geologic time.

• for a short span of geologic time.

• only on land.

• in a small part of Earth.

For the picture on page 216: How old are the rock layers in which ammonite fossils are found?

• 100 to 200 million years

• 180 to 206 million years

• 206 to 220 million years

• 220 to 300 million years

An organism that no longer exists on Earth is called

• Decayed
• Evolved
• Extinct
• Preserved

_{Which rock layer contains the newest fossils?}

• F
• E
• B
• C

Tags

NGSS.MS-ESS1-4

NGSS.MS-LS4-1

The best index fossils have which two traits?

• widespread geographically, long lifespan
• widespread geographically, short lifespan
• specific place, long lifespan
• specific place, short lifespan

Tags

NGSS.MS-LS4-1