There isn't a formal principle in paleontology called "paleontological identity." However, the concept you're likely referring to is the principle of fossil correlation, which is a fundamental principle in paleontology.

Here's what it means:

* Fossil Correlation: This principle states that fossils found in different locations can be used to establish the relative ages of rock layers. The idea is that if two rock layers contain the same unique fossils, they are likely to be from the same time period.

Key points about the principle of fossil correlation:

* Index Fossils: Certain fossils, known as index fossils, are particularly useful for correlation. These fossils are:

* Widely distributed geographically.

* Lived for a relatively short period of time.

* Easily recognizable.

* Biostratigraphy: The study of fossils in rock layers is called biostratigraphy. It's a key tool for establishing the relative ages of rocks and understanding the history of life on Earth.

* Limitations: Fossil correlation has limitations. For instance, the same fossil may appear in rocks of different ages in different locations, or fossils may be transported and deposited in younger rocks.

Let me know if you have any other questions!