Why is an ammonite considered an index fossil?

Question

1.They are easily identified
2.They existed for a fairly short period of time
3.They lived in a relatively large area
4.All of the above

Answer 1

An ammonite is considered an index fossil because it meets the criteria for being a good index fossil, which includes being easily identifiable, existing for a relatively short period of geological time, and having a wide geographic distribution. Therefore, the correct answer is:

4. All of the above.