Crossword Puzzle for Record of Time
Topics 1-3Interpreting the Fossil Record, Overview of Dating, and Relative Techniques


2. The approach to assigning species names to new fossil skeletons based on the idea that if two fossils look slightly different, they should be categorized as being from two different species. This approach emphasizes minor differences. People who maintain this approach are generally referred to in the biological sciences as "splitters".
5. The study of the fossil and archaeological record of humans and their primate ancestors.
10. The term for a date that gives the time of an event only with reference to another event that is not worldwide in scale. It only indicates that one event occurred earlier or later than another. For instance, the observation that strata 2 is younger than strata 1 beneath it in a geological deposit does not provide information about how many years ago strata 2 was laid down. It only indicates its age relative to strata 1.
11. The remains of a plant or animal of a species that is known to have lived only during a specific time period. The discovery of such a fossil in an archaeological site is circumstantial evidence of the approximate time period that it was occupied. These fossils can be used to relatively date the remains of our ancient ancestors if they were found in association with each them.
15. The term for breaks in the original stratigraphic sequence of a geological deposit.
16. The study of the conditions under which plants, animals, and other organisms become altered after death, buried, and sometimes preserved.
18. The name for the relative dating technique that is based on the discovery of index fossils.
19. The term for any remains or traces of ancient organisms. Often they are mineralized bone, though they may be animal tracks, frozen or desiccated bodies, creatures trapped in amber, etc.
20. The name of a presumably very ancient human skull and jaw found in England in 1912 by Charles Dawson. In 1953, this fossil was found to be an elaborate hoax.


1. The principle or idea that if there are layers in a sedimentary deposit, those laid down first will be on the bottom and those laid down last will be on the top. This principle is the basis for one of the commonly used relative dating techniques.
3. The approach to assigning species names to new fossil skeletons based on the idea that if two fossils have major similarities they should be categorized as being members of the same species. From this perspective, minor anatomical differences within the same population are expected since the members of living species have individual variation. People who advocate this viewpoint are also referred to in the biological sciences as "lumpers."
4. The study of earlier forms of all life present in the fossil record.
6. A term referring to the position in a site where an object was originally deposited. Finding an artifact or fossil undisturbed in this way allows a researcher to apply the principle of association in dating and interpreting it. This can not be done if the object is in a secondary context, which is to say that it was moved to a new location after the original deposition.
7. The term for a group of similar fossils whose range of morphological variation does not exceed the range of variation of a closely related living species.
8. The term for a fossil consisting of a bone that has lost its organic components and now consists only, or primarily, of minerals. This is characteristic of surviving dinosaur and other very ancient bones.
9. The principle or idea that if two objects are found undisturbed in the same strata of a site, they very likely date to the same time period.
12. A relative dating method based on the fact that bones buried in the ground progressively lose nitrogen and gain fluorine and other trace elements. If two bones from the same site have markedly different amounts of nitrogen and fluorine, it is a strong indication that they did not come from the same time period. The bone with the least amount of nitrogen and the greatest amount of fluorine is most likely the oldest.
13. The study of geological strata, or layers of rock or soil, usually for relative dating based on the principle of superposition.
14. The term for a date that places an event in its chronological position with reference to a universal time scale such as a calendar. Such dates usually are given in terms of the number of years before or after a calendar starting point. For instance, 1950 B.C. was 1950 years before the beginning date of the Gregorian calendar, which is commonly used today.
17. Permanently frozen soil. This is a common condition above the arctic circle and in other similarly cold environments.
18. A kind of chronometric date that is measured in years before the present.

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