Perhaps the most pressing issue in predicting biotic responses to present and future global change is understanding how environmental factors shape the relationship between ecological traits and extinction risk. The fossil record provides millions of years of insight into how extinction selectivity (i.e., differential extinction risk) is shaped by interactions between ecological traits and environmental conditions. Numerous paleontological studies have examined trait-based extinction selectivity; however, the extent to which these patterns are shaped by environmental conditions is poorly understood due to a lack of quantitative synthesis across studies. We conducted a meta-analysis of published studies on fossil marine bivalves and gastropods that span 458 million years to uncover how global environmental and geochemical changes covary with trait-based extinction selectivity. We focused on geographic range size and life habit (i.e., infaunal vs. epifaunal), two of the most important and commonly examined predictors of extinction selectivity. We used geochemical proxies related to global climate, as well as indicators of ocean acidification, to infer average global environmental conditions. Life-habit selectivity is weakly dependent on environmental conditions, with infaunal species relatively buffered from extinction during warmer climate states. In contrast, the odds of taxa with broad geographic ranges surviving an extinction (>2500 km for genera, >500 km for species) are on average three times greater than narrow-ranging taxa (estimate of odds ratio: 2.8, 95% confidence interval = 2.3-3.5), regardless of the prevailing global environmental conditions. The environmental independence of geographic range size extinction selectivity emphasizes the critical role of geographic range size in setting conservation priorities.

To interpret microbially influenced paleoenvironments in the sedimentary record, it is crucial to understand what processes control the development of microbial mats in modern environments. This article reports results from a multiyear study of Little Ambergris Cay, Turks and Caicos Islands, an uninhabited island floored by broad tracts of well‐developed microbial mats on the wind‐dominated and wave‐dominated Caicos Platform. Uncrewed aerial vehicle‐based imaging, differential global positioning system topographic surveys, radiocarbon data, and in situ sedimentological and microbial ecological observations were integrated to identify and quantify the environmental factors that influence the distribution and morphologies of Little Ambergris Cay microbial mats, including their response to large storm events. Based on these data, this study proposes that Little Ambergris Cay initially developed from the accretion and rapid lithification of carbonate sediment delivered by converging wave fronts in the lee of adjacent Big Ambergris Cay. Broad tracts of microbial mats developed during late Holocene time as the interior became restricted due to beach ridge development. Minor elevation differences regulate subaerial exposure time and lead to three categories of microbial mats, differentiated by surface texture and morphology: smooth mats, polygonal mats and blister mats. The surface texture and morphology of the mats is controlled by subaerial exposure time. In addition to elevation, the spatial distribution of mats is largely controlled by hydrodynamics and sediment transport during large storm events. This detailed assessment of the controls on mat formation and preservation at Little Ambergris Cay provides a framework within which to identify and understand the interactions between microbial communities and sediment transport processes in ancient high‐energy carbonate depositional systems.

As the most recent time in Earth history when global temperatures were warmer than at present, the peak of the last interglacial (Marine Isotope Substage [MIS] 5e; ~120,000 years ago) can serve as a pre-anthropogenic baseline for a warmer near-future world. Here we use a new compilation of 22 fossil localities in California that have been reliably dated to MIS 5e to establish baseline expectations for contemporary bivalve species movements by identifying and analyzing bivalve species with “extralimital” ranges, that is, species that occupied the California region during MIS 5e but are now restricted to adjacent regions. We find that 15% of species (n = 142) found in MIS 5e localities have extralimital ranges and currently occupy warmer waters to the south of the California region. The majority of extralimital occurrences occur in paleo-embayments, suggesting that these sheltered habitats were more suitable habitats for warm-water species than exposed coasts during the MIS 5e. We further find that extralimital species now tend to occur in cooler, more seasonally productive coastal waters and to occupy more offshore islands when compared with the broader species pool immediately south of California. These findings suggest that high dispersal potential and preexisting tolerances to environmental conditions similar to California's comparatively cool and seasonally productive environments may have enabled extralimital bivalves to colonize the California region during MIS 5e.