Fossils such as this one are dated using radioative and relative dating methods.
In history, archeology and science, the process of dating discoveries helps provide important information about the find. Dating a fossil, for example, can help scientists learn more about where the discovered creature fit into evolution or can assist them in identifying the specimen. Science uses relative and radioactive dating to determine the age of these discoveries, but these two methods are different.
History
Relative dating is the older of the two methods. Before the 1900s, any attempts to date discoveries had to be done by drawing conclusions from the find's location in the Earth's layers. Carbon dating, the most common form of radioactive dating, started being used after World War II.
Relative Dating and Stratigraphy
With relative dating, scientists rely on stratigraphy to determine the age of a discovery. Stratigraphy says lower layers of earth are older than the ones above them. Plus, the presence of certain animal and plant fossils in a particular layer gives scientists an idea of the time period represented by that layer. Using this information, researchers can approximate the age of a discovery based on where it was found in the earth's layers.
Radioactive Dating and Half-Life
Radioactive elements change over time. For example, uranium sheds atoms on a set schedule until it changes into a different element. The time it takes for 50 percent of a radioactive element to change is called its half-life. This process is known as radioactive decay. By measuring the decay of these elements in a discovery, scientists can determine the age of that discovery.
Reliability of Dating
Relative dating allows scientists to fit a discovery into the larger chronology of the Earth. For example, a fossil may be determined to be more recent than another discovery based on this method of dating. With radioactive dating, which is also referred to as absolute dating, scientists can determine a more specific age for the discovery. For instance, they can say the finding is 50,000 years old. While both forms of dating produce different types of results, both results need to mesh. If relative dating suggests the fossil should be younger than 50,000 years old but radioactive dating says it should be older than that, a problem exists with the dating.
Benefits of Radioactive Dating
Researchers trust radioactive dating for two reasons. First, the half-life of radioactive elements is well-established and recorded. If half of the carbon-14 element in a fossil has changed, the age of the fossil would be 5,730 years old because that is the element's half-life. Second, the half-life of these elements does not change because of environmental effects. The half-life does not increase in hot weather, for instance. That means the measurement remains stable and reliable regardless of the environmental changes taking place at different times in the Earth's history.
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