The beginning and end of each chunk of time in the geologic time scale is determined by when some species appeared or disappeared from the fossil record. When many species went extinct around the same ...

Numerical ages estimate the date of a geological event and can sometimes reveal quite precisely when a fossil species existed in time. Third, magnetism in rocks can be used to estimate the age of ...

The geological time scale, established by scientists in the ... and epochs based on fossil evidence. In this feature, explore the history of life on Earth as we know it today, from the earliest ...

A new epoch would mean that a distinct change could be seen in the fossil record with geological ... "An epoch in the geologic time scale is defined by a clean planetary break in time.

By looking at differences among the fossils over time, the researchers learned that while the fish's large-scale features, like its body shape, have stayed consistent since the Cretaceaous more ...

A Timescale is a scale used to represent periods of time ... of the Earth that is characteristic of a particular span of geologic time or environment. We will look at a few index fossils and see if we ...