Along with this sedimentary correlation, they noted that the best index fossils to identify the biota are " Peipiaosteus " and " Lycoptera ".
32.
Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geologic time periods.
33.
Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geological time periods.
34.
Some echinoids, such as " Micraster ", which is found in the Cretaceous period Chalk Formation of England and France, serve as zone or index fossils.
35.
The best index fossils are common, easy to identify at species level and have a broad distribution otherwise the likelihood of finding and recognizing one in the two sediments is poor.
36.
The series of deposits that spans the occurrence of a particular index fossil, is often referred to as that fossil's zone, enabling to relate different faunas through time.
37.
The use of index fossils became a powerful tool for making geological maps, because it allowed geologists to correlate the rocks in one locality with those of similar age in other, distant localities.
38.
Because they appeared quickly in geological time, and moulted like other arthropods, trilobites serve as excellent index fossils, enabling geologists to date the age of the rocks in which they are found.
39.
Usually one or more index fossils that are common, found worldwide, easily recognized, and limited to a single, or at most a few, stages are used to define the stage's bottom.
40.
Some belemnoids ( such as " Belemnites " of Belemnitida ) serve as index fossils, particularly in the Cretaceous Chalk Formation of Europe, enabling geologists to date the age the rocks in which they are found.
