= Solution
Four documented examples, each tied to its actual context, are:
* \b[Geographic range:] widespread marine <bivalve> genera survived the end-<Cretaceous> event better than geographically restricted genera. Spatial spread can reduce exposure to some geographically heterogeneous stresses, although this does not guarantee survival of a global perturbation.<Selectivity of end-Cretaceous marine bivalve extinctions by David Jablonski and others>[Abstract: lower extinction intensity in geographically widespread genera]{ref}
* \b[<Body size>:] large-bodied <mammals> were disproportionately lost during the late <Quaternary>. The global analysis documents size selectivity across continents and trophic groups; this is not evidence that large <body size> always raises <extinction> risk in every geological interval.<Body size downgrading of mammals over the late Quaternary by Felisa Smith and others>[Abstract: size-selective losses over the studied late-Quaternary intervals]{ref}
* \b[Physiological buffering and respiratory capacity:] poor capacity to tolerate elevated <carbon dioxide> and associated <oxygen> stress has been linked to higher vulnerability among end-<Permian> marine groups. This is a paleophysiological interpretation informed by living relatives and <fossil> traits, rather than a direct measurement of a <fossil> animal’s tolerance.<Paleophysiology and end-Permian mass extinction by Andrew H. Knoll and others>[Abstract and section Extinction in the oceans: hypercapnia vulnerability and physiological selectivity]{ref}
* \b[<Sexual dimorphism> as a proxy for male reproductive investment:] greater male–female carapace differences in <fossil> cytheroid <ostracods> were associated with higher estimated <extinction> rates. The measured <fossil> trait is dimorphism; interpreting it as investment requires the biological correspondence observed in living relatives.<High male sexual investment as a driver of extinction in fossil ostracods by Maria João Fernandes Martins and others>[Abstract: dimorphic fossil carapaces and association with estimated extinction rates]{ref}
These examples demonstrate event- and group-dependent selectivity. They do not define one universal vulnerability ranking: the <bivalve> study, for instance, did not find body-size selectivity at the same end-Cretaceous genus-level event.
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