The Batocrinidae are characteristic faunal elements in lower Mississippian shallow-marine settings in North America. Recent delineation of objectively defined genera allows a reexamination of batocrinid species and their distribution in the Fort Payne Formation (early Viséan, late Osagean), a well-studied array of carbonate and siliciclastic facies. The Fort Payne batocrinid fauna has fourteen species assigned to six genera, plus hybrid specimens. Magnuscrinus spinosus (Miller and Gurley, 1895a) is reassigned to its original placement in Eretmocrinus....

Death assemblages that occupy the upper tens of centimeters of sediment in shallow-marine settings are often subject to extensive mixing, thereby limiting their usefulness in assessing environmentally mediated compositional changes through time in the local biota. Here, we provide evidence that dense, Thalassia-rich seagrass beds preserve a stratigraphic record of biotic variation because their dense root–rhizome mats inhibit mixing. We sampled benthic mollusk assemblages at seven localities in Thalassia-rich beds around St. Croix, USVI, collecting...

The vertebrate extinction rate over the past century is approximately 22–100 times greater than background extinction rates, and large mammals are particularly at risk. Quaternary megafaunal extinctions have been attributed to climate change, overexploitation, or a combination of the two. Rhinoceroses (Family: Rhinocerotidae) have a rich fossil history replete with iconic examples of climate-induced extinctions, but current pressures threaten to eliminate this group entirely. The Sumatran rhinoceros (Dicerorhinus sumatrensis) is among the most imperiled mammals...

Well-established causal links exist between maternal nutritional deficits and embryo health and viability. By contrast, environmental effects operating through the father that could influence embryo mortality have seldom been examined. Yet, ejaculates can require non-trivial resource allocation, and seminal plasma components are increasingly recognized to exert wide-ranging effects on females and offspring, so paternal dietary effects on the embryo should be expected. We test for effects of varying levels of protein (P), carbohydrate (C) and...

Understanding the origin and maintenance of functionally important subordinate traits is a major goal of evolutionary physiologists and ecomorphologists. Within the confines of a limbless body plan, snakes are diverse in terms of body size and ecology, but we know little about the functional traits that underlie this diversity. We used a phylogenetically diverse group of 131 snake species to examine associations between habitat use, sidewinding locomotion, and constriction behavior with the number of body...

The origins of evolutionary radiations are often traced to the colonization of novel adaptive zones, including unoccupied habitats or unutilized resources. For herbivorous insects, the predominant mechanism of diversification is typically assumed to be a shift onto a novel lineage of host plants. However, other drivers of diversification are important in shaping evolutionary history, especially for groups residing in regions with complex geological histories. We evaluated the contributions of shifts in host plant clade, bioregion,...

Beak shape in Darwin's ground finches (Geospiza) is emblematic of natural selection and adaptive radiation, yet our understanding of the genetic basis of beak shape variation, and thus the genetic target of natural selection, is still evolving. Here we reveal the genomic architecture of beak shape variation using genomewide comparisons of four closely related and hybridizing species across 13 islands subject to parallel natural selection. Pairwise contrasts among species were used to identify a large...

Evolving interactions between predators and prey constitute one of the major adaptive influences on marine animals during the Paleozoic. Crinoids and fish constitute a predator-prey system that may date back to at least the Silurian, as suggested by patterns of crinoid regeneration and spinosity in concert with changes in the predatory fauna. Here we present data on the frequency of breakage and regeneration in the spines of the Middle Devonian camerate Gennaeocrinus and Late Paleozoic...