Evolutionary rates and patterns among Cretaceous Bivalvia

Abstract

Analyses of over 100 lineages of Cretaceous Mollusca, primarily Bivalvia, representing diverse levels of morphological complexity, habitats, and adaptive strategies, clearly show that evolutionary rates (new taxa/unit time; or average taxa duration) vary widely within lineages subjected to changing environmental stresses, and between lineages and/or adaptive strategies subjected to broadly similar sets of environmental parameters through time. Modes of evolution range from gradualistic to punctuated, dependent upon rates and intensity of change in stress, or on levels of ecological opportunity (available ecospace). Extremely rapid rates of species evolution (one sp./0.08 Ma) and abrupt appearance of higher taxa occur during rapid radiations into unoccupied ecospace, and/or during high stress situations affecting whole biotas during short time intervals (e.g. rapid marine regression). Classification and reconstruction of molluscan phylogeny is most difficult over these intervals of geological time. Ecological factors far outweigh purely genetic factors in determining evolutionary rates and patterns among Mollusca, as determined by tests applied to Cretaceous lineages.

Larval Ecology of Marine Benthic Invertebrates: Paleobiological Implications

“…However, benthic species tolerant enough, and having larvae with a sufficient planktic duration, to maintain a broad geographic distribution would not be expected to evolve very rapidly, in terms of either speciation or extinction rates (see preceding section). Some other aspect of the organisms' biology, for example trophic level and/or adult ecology (Levinton, 1974;Alexander, 1977;Kauffman, 1978; and many others) must play a key role in keeping certain widespread lineages subject to high extinction rates.…”

Treatise Online, no. 29: Part N, Revised, Volume 1, Chapter 24: Extinction in the marine Bivalvia

“…Bivalves are no exception; indeed, several classic studies of extinction selectivity have focused on the long and relatively well-preserved fossil record of marine bivalves (e.g., bretsky, 1973;kauFFman, 1978;jablonski, 1986;stanley, 1986a;jablonski, 2005). This is in part because bivalves display sufficient variation among taxa in traits such as morphology, feeding mode, life habit, larval type, geographic range, and stratigraphic range to allow workers to independently test the extent to which these traits relate to taxon survivorship.…”

“…leVinton's (1974) observation that genera of deposit-feeding bivalves were geologically longer-lived than suspensionfeeders, has inspired an ongoing debate over whether bivalves with different feeding modes experience different extinction trajectories. Building on this work, a qualitative examination of background extinction in Cretaceous bivalve species documented particularly slow rates of evolution and long stratigraphic durations in deposit-feeders relative to suspension-feeders (kauFFman, 1978). The majority of studies that have explicitly tested for extinction selectivity according to feeding mode have focused on the K/Pg event, with mixed results.…”

Ammonite Biostratigraphy of the Cretaceous—An Overview

“…Cretaceous macrobiostratigraphy mainly relies on ammonites, but a precise stratigraphic subdivision as well as correlation on a supra-regional scale is also possible with inoceramid bivalves (e.g., Kauffman 1978;Tröger 1989;Yazykova 2004). This is surprising since bivalves in general have the disadvantage that they are more strongly influenced by facies and substrate changes compared to ammonites.…”