Taxonomic Extinction Intensity Percentage
Computes the percentage of marine genera or families that vanished during mass extinction boundaries (e.g. End-Permian P-Tr, End-Cretaceous K-Pg).
\[ E_{\%} = \frac{N_{extinct}}{N_{total}} \cdot 100\% = \frac{N_{FAD \le t \le LAD}}{N_{standing}} \cdot 100\% \]
Plain Text Formula:
E_percent = (N_extinct / N_total) * 100
📐 Variable Definitions & Parameters
| Symbol | Variable Name | Standard Unit | Physical Definition |
|---|---|---|---|
| \[ E_{\%} \] | Extinction Intensity | percentage (%) | Proportion of taxa eradicated during the biozone interval |
| \[ N_{extinct} \] | Number of Extinct Taxa | count | Number of genera/species having their LAD in the target interval |
| \[ N_{total} \] | Standing Diversity | count | Total diversity present in the stratigraphic window prior to extinction |
💡 Worked Engineering Example
Problem Statement:
During the End-Permian extinction (251.9 Ma), 81% of marine species and 70% of terrestrial vertebrate families went extinct. Express genus-level kill curve.
Step-by-Step Solution:
- Of ~15,000 recorded marine fossil genera, ~12,450 suffered LAD
- E_percent = (12,450 / 15,000) * 100% = 83%
🎯 Result: End-Permian mass extinction intensity was 83% at the genus level and 96% at the species level.