 Solution

Extinction selectivity is systematic variation in the probability or rate of extinction among lineages with different traits, rather than trait-independent loss. Traits may be biological, ecological or geographical: for example, survival may differ between narrow-ranging and widespread taxa within the same extinction interval.

A test needs an explicit denominator of taxa at risk, a defined taxonomic level and time window, and a specified trait measurement. Regional disappearance is not automatically global extinction. Nor is an association necessarily a causal mechanism: traits covary with habitat, abundance and preservation, and their effects can change between background intervals and mass extinctions.