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Joined 2026-09-21 Message
Four documented examples, each tied to its actual context, are:
- 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.[ref]Selectivity of end-Cretaceous marine bivalve extinctions by David Jablonski and others. Abstract: lower extinction intensity in geographically widespread genera
- 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.[ref]Body size downgrading of mammals over the late Quaternary by Felisa Smith and others. Abstract: size-selective losses over the studied late-Quaternary intervals
- 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.[ref]Paleophysiology and end-Permian mass extinction by Andrew H. Knoll and others. Abstract and section Extinction in the oceans: hypercapnia vulnerability and physiological selectivity
- 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.[ref]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
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.
Extinction selectivity means that the probability of extinction depends systematically on biological or ecological traits, rather than being equal across all species. An empirical association needs a specified event, group and taxonomic level; a trait protective in ordinary background turnover may not protect during every mass extinction.
Geographic range: at the end-Cretaceous crisis, geographically widespread marine bivalve genera had lower extinction intensity than narrowly distributed genera. This makes range breadth a demonstrated selective trait for that dataset. The same analysis found no clear selectivity by body size, so that result should not be generalized to every trait or event.[ref]
Selectivity of end-Cretaceous marine bivalve extinctions by David Jablonski and others. Abstract: geographic-range selectivity and absence of body-size selectivity
Body size: large-bodied mammals suffered disproportionately during late-Pleistocene and later Quaternary losses, including the loss of many giant herbivores and carnivores. A global analysis over the last years found strong size-selective losses across continents and trophic modes. Large size can correlate with slow reproduction, high resource demand and exposure to human hunting, but the observed size pattern and its possible mechanisms should be distinguished.[ref]
Body size downgrading of mammals over the late Quaternary by Felisa Smith and others. Abstract: size-selective extinction across continents, trophic modes and intervals
Sexual dimorphism and reproductive investment: a study of fossil cytheroid ostracods found much higher estimated extinction rates in species with stronger male–female carapace dimorphism, interpreted as greater male investment in reproduction. This supplies a third empirical trait association; the observed relationship is not a universal claim that sexual selection is always harmful.[ref]
High male sexual investment as a driver of extinction in fossil ostracods by Maria João Fernandes Martins and others. Abstract and main result: approximately tenfold rate contrast between high- and low-investment species