Relationship between tooth macrowear and jaw morphofunctional traits in representative hypercarnivores.

The mammalian adult dentition is a non-renewable resource. Tooth attrition and disease must be accommodated by individuals using behavioral, physiological, and/or musculoskeletal shifts to minimize impact on masticatory performance. From a biomechanical perspective, the musculoskeletal system becomes less efficient at producing bite force for a given amount of muscle input force over an individual's life, because tooth-food contact area increases as cusps wear.

Pre-Younger Dryas megafaunal extirpation at Rancho La Brea linked to fire-driven state shift.

The cause, or causes, of the Pleistocene megafaunal extinctions have been difficult to establish, in part because poor spatiotemporal resolution in the fossil record hinders alignment of species disappearances with archeological and environmental data. We obtained 172 new radiocarbon dates on megafauna from Rancho La Brea in California spanning 15.6 to 10.

Global long-term stability of individual dietary specialization in herbivorous mammals.

Dietary variation within species has important ecological and evolutionary implications. While theoreticians have debated the consequences of trait variance (including dietary specialization), empirical studies have yet to examine intraspecific dietary variability across the globe and through time. Here, we use new and published serial sampled δC values of herbivorous mammals from the Miocene to the present (318 individuals summarized, 4134 samples) to examine how dietary strategy (i.

Larisa DeSantis.

Interview with Larisa DeSantis, who uses fossil mammals to study ancient climate change and extinctions, with a view to understand past and present ecosystems, at Vanderbilt University.

Dietary ecology of the scimitar-toothed cat Homotherium serum.

The scimitar-toothed cat Homotherium was one of the most cosmopolitan cats of the Pleistocene, present throughout Eurasia, Africa, and the Americas until at least ~28 thousand years ago. Friesenhahn Cave (Bexar County, Texas) contains some of the best-preserved specimens of Homotherium serum alongside an abundance of juvenile mammoths, leading some to argue that H. serum preferentially hunted juvenile mammoths.

Dietary plasticity of North American herbivores: a synthesis of stable isotope data over the past 7 million years.

Palaeoecological interpretations are based on our understanding of dietary and habitat preferences of fossil taxa. While morphology provides approximations of diets, stable isotope proxies provide insights into the realized diets of animals. We present a synthesis of the isotopic ecologies (C from tooth enamel) of North American mammalian herbivores since approximately 7 Ma.

Dietary ecology of Alaskan polar bears (Ursus maritimus) through time and in response to Arctic climate change.

Arctic climate change poses serious threats to polar bears (Ursus maritimus) as reduced sea ice makes seal prey inaccessible and marine ecosystems undergo bottom-up reorganization. Polar bears' elongated skulls and reduced molar dentition, as compared to their sister species the grizzly bear (Ursus arctos), are adaptations associated with hunting seals on sea ice and a soft, lipid-rich diet of blubber and meat. With significant declines in sea ice, it is unclear if and how polar bears may be altering their diets.

Ecosystem engineering in the Quaternary of the West Coast of South Africa.

Despite advances in our understanding of the geographic and temporal scope of the Paleolithic record, we know remarkably little about the evolutionary and ecological consequences of changes in human behavior. Recent inquiries suggest that human evolution reflects a long history of interconnections between the behavior of humans and their surrounding ecosystems (e.g.

Early specialized maritime and maize economies on the north coast of Peru.

We assess diet and economies of middle Holocene (∼7,500 to 4,000 calibrated [cal] B.P.) humans at coexisting mound sites (Huaca Prieta and Paredones) in north coastal Peru and document regular consumption of maize by ∼6,500 to 6,000 cal B.

An eye for a tooth: was not a marsupial "saber-tooth predator".

Background: Saber-toothed mammals, now all extinct, were cats or "cat-like" forms with enlarged, blade-like upper canines, proposed as specialists in taking large prey. During the last 66 Ma, the saber-tooth ecomorph has evolved convergently at least in five different mammalian lineages across both marsupials and placentals. Indeed, , the so-called "marsupial saber-tooth," is often considered as a classic example of convergence with placental saber-tooth cats such as .

Clarifying relationships between cranial form and function in tapirs, with implications for the dietary ecology of early hominins.

Paleontologists and paleoanthropologists have long debated relationships between cranial morphology and diet in a broad diversity of organisms. While the presence of larger temporalis muscle attachment area (via the presence of sagittal crests) in carnivorans is correlated with durophagy (i.e.

Reply to Van Valkenburgh et al.

DeSantis et al. respond to the concerns raised by Van Valkenburgh et al. on their original study.

Causes and Consequences of Pleistocene Megafaunal Extinctions as Revealed from Rancho La Brea Mammals.

The fossils preserved in the Rancho La Brea "tar" seeps in southern California span the past ∼50,000 years and provide a rare opportunity to assess the ecology of predators (e.g., the American lion, sabertooth cats, cougars, dire wolves, gray wolves, and coyotes), including clarifying the causes and consequences of the terminal Pleistocene extinction event.

A year in the life of a giant ground sloth during the Last Glacial Maximum in Belize.

Stable isotope analysis of the first fossilized remains from Belize offers valuable insights into the conditions within which this individual lived and its ability to adapt to the increasing aridity of the Last Glacial Maximum (LGM). Cathodoluminescence (CL) microscopy was used to identify chemical alteration of the tooth during fossilization. Results demonstrate that the inner orthodentin resists diagenesis, yielding potentially unaltered values.

The phylogenetic signal in tooth wear: What does it mean?

A new study by Fraser et al (2018) urges the use of phylogenetic comparative methods, whenever possible, in analyses of mammalian tooth wear. We are concerned about this for two reasons. First, this recommendation may mislead the research community into thinking that phylogenetic signal is an artifact of some sort rather than a fundamental outcome of the evolutionary process.

Effects of climate on dental mesowear of extant koalas and two broadly distributed kangaroos throughout their geographic range.

Dental mesowear analysis can classify the diets of extant herbivores into general categories such as grazers, mixed-feeders, and browsers by using the gross wear patterns found on individual teeth. This wear presumably results from both abrasion (food-on-tooth wear) and attrition (tooth-on-tooth wear) of individual teeth. Mesowear analyses on extinct ungulates have helped generate hypotheses regarding the dietary ecology of mammals across space and time, and recent developments have expanded the use of dental mesowear analysis to herbivorous marsupial taxa including kangaroos, wombats, possums, koalas, and relatives.

Dietary behaviour of man-eating lions as revealed by dental microwear textures.

Lions (Panthera leo) feed on diverse prey species, a range that is broadened by their cooperative hunting. Although humans are not typical prey, habitual man-eating by lions is well documented. Fathoming the motivations of the Tsavo and Mfuwe man-eaters (killed in 1898 in Kenya and 1991 in Zambia, respectively) may be elusive, but we can clarify aspects of their behaviour using dental microwear texture analysis.

Cougars' key to survival through the Late Pleistocene extinction: insights from dental microwear texture analysis.

Cougars (Puma concolor) are one of only two large cats in North America to have survived the Late Pleistocene extinction (LPE), yet the specific key(s) to their relative success remains unknown. Here, we compare the dental microwear textures of Pleistocene cougars with sympatric felids from the La Brea Tar Pits in southern California that went extinct at the LPE (Panthera atrox and Smilodon fatalis), to clarify potential dietary factors that led to the cougar's persistence through the LPE. We further assess whether the physical properties of food consumed have changed over time when compared with modern cougars in southern California.

Was the giant short-faced bear a hyper-scavenger? A new approach to the dietary study of ursids using dental microwear textures.

Dramatic environmental changes associated with global cooling since the late Miocene, and the onset of glacial-interglacial cycles in the Pleistocene served as a backdrop to the evolutionary radiation of modern bears (family Ursidae). These environmental changes likely prompted changes in food availability, and triggered dietary adaptations that served as motive forces in ursid evolution. Here, we assess correspondence of dental microwear textures of first and second lower molars with diet in extant ursids.

Is Rapoport's rule a recent phenomenon? A deep time perspective on potential causal mechanisms.

Macroecology strives to identify ecological patterns on broad spatial and temporal scales. One such pattern, Rapoport's rule, describes the tendency of species' latitudinal ranges to increase with increasing latitude. Several mechanisms have been proposed to explain this rule.

Direct comparisons of 2D and 3D dental microwear proxies in extant herbivorous and carnivorous mammals.

The analysis of dental microwear is commonly used by paleontologists and anthropologists to clarify the diets of extinct species, including herbivorous and carnivorous mammals. Currently, there are numerous methods employed to quantify dental microwear, varying in the types of microscopes used, magnifications, and the characterization of wear in both two dimensions and three dimensions. Results from dental microwear studies utilizing different methods are not directly comparable and human quantification of wear features (e.

Implications of diet for the extinction of saber-toothed cats and American lions.

The saber-toothed cat, Smilodon fatalis, and American lion, Panthera atrox, were among the largest terrestrial carnivores that lived during the Pleistocene, going extinct along with other megafauna ∼12,000 years ago. Previous work suggests that times were difficult at La Brea (California) during the late Pleistocene, as nearly all carnivores have greater incidences of tooth breakage (used to infer greater carcass utilization) compared to today. As Dental Microwear Texture Analysis (DMTA) can differentiate between levels of bone consumption in extant carnivores, we use DMTA to clarify the dietary niches of extinct carnivorans from La Brea.

Mammalian niche conservation through deep time.

Climate change alters species distributions, causing plants and animals to move north or to higher elevations with current warming. Bioclimatic models predict species distributions based on extant realized niches and assume niche conservation. Here, we evaluate if proxies for niches (i.