= Solution
One fossil-record study is \b[<Selectivity of end-Cretaceous marine bivalve extinctions by David Jablonski and others>], which compared survival of marine <bivalve> genera across the end-<Cretaceous> <mass extinction> against their pre-event attributes. Geographically widespread genera had lower <extinction> intensity than narrowly distributed ones. In the same analysis, <body size>, burrowing versus exposed life position, and shelf bathymetric position were not significant selectors; the apparent feeding-mode contrast was concentrated in particular groups rather than establishing a universal feeding rule.<Selectivity of end-Cretaceous marine bivalve extinctions by David Jablonski and others>[Science 268, pp. 389–391, abstract: tested traits, range result and qualifications to the feeding-mode result]{ref}
The logic of the test is to define the pre-event genera at risk, classify their geographic ranges using pre-event occurrences, then compare the fractions becoming extinct. Using pre-event rather than surviving ranges avoids measuring the predictor after the outcome. A two-by-two <contingency table> gives an elementary broad/narrow-range comparison; a <logistic regression> can instead retain a continuous range measure and include correlated covariates. These are explanations of the inferential design, not a claim that this paper used that exact regression specification.
A persuasive interpretation must address unequal rock exposure, collecting intensity, taxonomic revision, incomplete occurrence records and the difference between local loss and global <extinction>. The important result is selective survival in a real <fossil> dataset and the failure of several plausible alternative predictors in that setting. It is observational evidence: geographic range can correlate with unmeasured ecological properties, so the association alone does not prove a unique kill mechanism.
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