Ancient dating methods
Biologists actually have at their disposal several independent ways of looking at the history of life - not only from the order of fossils in the rocks, but also through phylogenetic trees. Relative dating is done by observing fossils, as described above, and recording which fossil is younger, which is older.The discovery of means for absolute dating in the early 1900s was a huge advance.These demonstrate that, of course, we do not know everything (and clearly never will), but we know enough.Today, innovative techniques provide further confirmation and understanding of the history of life.He has written some 30 books on dinosaurs and paleobiology, ranging from professional tomes to popular kids’ books. Learn the facts in Evolution 101, browse the resource library, read about evolution in the news, or discover a wealth of materials to help educate others about evolution and related concepts—it’s all right here!
For example, it has been known since the 1960s that the famous Cretaceous-Tertiary boundary, the line marking the end of the dinosaurs, was 65 million years old.
Early geologists, in the 1700s and 1800s, noticed how fossils seemed to occur in sequences: certain assemblages of fossils were always found below other assemblages. Since 1859, paleontologists, or fossil experts, have searched the world for fossils.
In the past 150 years they have not found any fossils that Darwin would not have expected.
The methods are all based on radioactive decay: The first radiometric dates, generated about 1920, showed that the Earth was hundreds of millions, or billions, of years old.
Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates.
Search for ancient dating methods:
Radiocarbon dating of artifacts from Egypt’s Pre-dynastic period and First Dynasty, reported September 4th in the Proceedings of the Royal Society A by Michael Dee and colleagues, suggests Egypt is younger than previously thought.