why are epochs only listed in the Cenozoic era
Epochs are not only listed in the Cenozoic era, but they are more commonly used and well-defined in this era compared to the others. The Cenozoic era is the most recent geologic era, covering the last 66 million years, and it is subdivided into several epochs.
The reason epochs are more extensively used in the Cenozoic era is because this period is relatively more well-documented and studied compared to earlier eras. The fossil record from this era is abundant and diverse, allowing for the identification of distinct and recognizable boundaries between different epochs. Furthermore, the Cenozoic era is closer to the present time, making it more relatable and easier to establish correlations with existing flora, fauna, and geological records.
In contrast, epochs in earlier eras, such as the Paleozoic and Mesozoic, are less defined and less commonly used. The boundaries between different epochs in these eras are often less clear due to limited fossil records, less information, and greater tectonic activities and changes that have affected the preservation of geological and biological records.
Although the use of epochs extends beyond the Cenozoic era, they are not as prominently used or as well-differentiated in those eras due to the inherent limitations of the geological and fossil records from those time periods.