Pronghorn () enamel phosphate δO values reflect climate seasonality: Implications for paleoclimate reconstruction.

Stable oxygen isotope (δO) compositions from vertebrate tooth enamel are widely used as biogeochemical proxies for paleoclimate. However, the utility of enamel oxygen isotope values for environmental reconstruction varies among species. Herein, we evaluate the use of stable oxygen isotope compositions from pronghorn ( Gray, 1866) enamel for reconstructing paleoclimate seasonality, an elusive but important parameter for understanding past ecosystems.

Problems with inferring a lack of competition between Rancho La Brea dire wolves and sabertooth cats based on dental enamel.

Van Valkenburgh et al. challenge the conclusions of a recent study by DeSantis et al. that claimed that sabertooth cats and dire wolves did not compete for similar prey.

Humans permanently occupied the Andean highlands by at least 7 ka.

High-elevation environments above 2500 metres above sea level (m.a.s.

Aquatic Habits of Cetacean Ancestors: Integrating Bone Microanatomy and Stable Isotopes.

The earliest cetaceans were interpreted as semi-aquatic based on the presence of thickened bones and stable oxygen isotopes in tooth enamel. However, the origin of aquatic behaviors in cetacean relatives (e.g.

Controlled feeding trials with ungulates: a new application of in vivo dental molding to assess the abrasive factors of microwear.

Microwear, the quantification of microscopic scratches and pits on the occlusal surfaces of tooth enamel, is commonly used as a paleodietary proxy. For ungulates (hoofed mammals), scratch-dominant microwear distinguishes modern grazers from browsers, presumably as a result of abrasion from grass phytoliths (biogenic silica). However, it is also likely that exogenous grit (i.

Functional implications of variation in tooth spacing and crown size in pinnipedimorpha (mammalia: carnivora).

Pinnipeds (seals, sea lions, and walruses) show variation in tooth morphology that relates to ecology. However, crown size and spacing are two aspects of morphology that have not been quantified in prior studies. We measured these characters for nearly all extant pinnipeds and three fossil taxa and then determined the principal sources of variation in tooth size and spacing using principal components (PCAs) and hierarchical cluster analysis (HCA).

Cope's rule and the evolution of body size in Pinnipedimorpha (Mammalia: Carnivora).

Cope's rule describes the evolutionary trend for animal lineages to increase in body size over time. In this study, we tested the validity of Cope's rule for a marine mammal clade, the Pinnipedimorpha, which includes the extinct Desmatophocidae, and extant Phocidae (earless seals), Otariidae (fur seals and sea lions), and Odobenidae (walruses). We tested for the presence of Cope's rule by compiling a large dataset of body size data for extant and fossil pinnipeds and then examined how body size evolved through time.

Unique biochemical and mineral composition of whale ear bones.

Abstract Cetaceans are obligate aquatic mammals derived from terrestrial artiodactyls. The defining characteristic of cetaceans is a thick and dense lip (pachyosteosclerotic involucrum) of an ear bone (the tympanic). This unique feature is absent in modern terrestrial artiodactyls and is suggested to be important in underwater hearing.

Predictive equations for the estimation of body size in seals and sea lions (Carnivora: Pinnipedia).

Body size plays an important role in pinniped ecology and life history. However, body size data is often absent for historical, archaeological, and fossil specimens. To estimate the body size of pinnipeds (seals, sea lions, and walruses) for today and the past, we used 14 commonly preserved cranial measurements to develop sets of single variable and multivariate predictive equations for pinniped body mass and total length.

Fluvial response to abrupt global warming at the Palaeocene/Eocene boundary.

Climate strongly affects the production of sediment from mountain catchments as well as its transport and deposition within adjacent sedimentary basins. However, identifying climatic influences on basin stratigraphy is complicated by nonlinearities, feedback loops, lag times, buffering and convergence among processes within the sediment routeing system. The Palaeocene/Eocene thermal maximum (PETM) arguably represents the most abrupt and dramatic instance of global warming in the Cenozoic era and has been proposed to be a geologic analogue for anthropogenic climate change.

Ontogenetic variations in Sr/Ca and Ba/Ca ratios of dental bioapatites from Bos taurus and Odocoileus virginianus.

Sr/Ca and Ba/Ca ratios of bone are commonly used as biochemical indicators of trophic level in modern and fossil mammals. Concerns over the effects of diagenesis on Sr/Ca and Ba/Ca ratios of bone led archaeologists and paleontologists to favor tooth enamel, which is less prone to alteration. Sr/Ca and Ba/Ca ratios of bone, enamel, and dentin from three farm-raised steers (Bos taurus) and five wild white-tailed deer (Odocoileus virginianus) from central Missouri were compared.

Latitudinal gradients in greenhouse seawater δ(18) O: evidence from Eocene sirenian tooth enamel.

The Eocene greenhouse climate state has been linked to a more vigorous hydrologic cycle at mid- and high latitudes; similar information on precipitation levels at low latitudes is, however, limited. Oxygen isotopic fluxes track moisture fluxes and, thus, the δ(18)O values of ocean surface waters can provide insight into hydrologic cycle changes. The offset between tropical δ(18)O values from sampled Eocene sirenian tooth enamel and modern surface waters is greater than the expected 1.

Whales originated from aquatic artiodactyls in the Eocene epoch of India.

Although the first ten million years of whale evolution are documented by a remarkable series of fossil skeletons, the link to the ancestor of cetaceans has been missing. It was known that whales are related to even-toed ungulates (artiodactyls), but until now no artiodactyls were morphologically close to early whales. Here we show that the Eocene south Asian raoellid artiodactyls are the sister group to whales.

Differentiating aquatic mammal habitat and foraging ecology with stable isotopes in tooth enamel.

We analyzed the carbon and oxygen isotope composition of tooth enamel from mammals inhabiting marine and terrestrial ecosystems to determine whether these stable isotopes were robust indicators of foraging and habitat preferences. Consumers were separated into six habitats (offshore, nearshore, kelp beds, estuarine, freshwater, terrestrial). Consumer δC values were correlated with the δC values of primary producers within each habitat, suggesting that δC values of tooth enamel are a viable proxy for foraging zones.