Ecometrics demonstrates that the functional dental traits of carnivoran communities are filtered by climate.

Terrestrial carnivorans, with their diverse diets and unique adaptations such as the carnassial tooth, offer insights into the connections between functional traits and the climatic and environmental conditions they inhabit. They shed light on functional trait-environment relationships at the highest trophic levels across a broad range of environmental conditions. In this study, we evaluate the relationship between relative blade length (RBL) of the lower carnassial tooth, a key dietary adaptation among terrestrial carnivorans for slicing and grinding food items, and climate.

Conservation of rib skeleton regionalization in the homoplastic evolution of the snake-like body form in squamates.

Squamates have independently evolved an elongate, limb-reduced body form numerous times. This transition has been proposed to involve either changes to regulatory gene expression or downstream modification of target enhancers to produce a homogeneous, deregionalized axial skeleton. Analysis of vertebral morphology has suggested that regionalization is maintained in snake-like body forms, but morphological variation in the other primary component of the axial skeleton, the dorsal ribs, has not been previously examined.

Squamate scavenging services: Heath goannas () support carcass removal and may suppress agriculturally damaging blowflies.

Human-induced environmental change has caused widespread loss of species that support important functions for ecosystems and society. For example, vertebrate scavengers contribute to the functional health of ecosystems and provide services to agricultural landscapes by removing carcasses and associated pests. Widespread extirpation of native Australian mammals since the arrival of Europeans in Australia has removed many scavenging species from landscapes, while scavenging mammals such as European red foxes () have been introduced.

The first Miocene fossils from coastal woodlands in the southern East African Rift.

The Miocene was a key time in the evolution of African ecosystems witnessing the origin of the African apes and the isolation of eastern coastal forests through an expanding arid corridor. Until recently, however, Miocene sites from the southeastern regions of the continent were unknown. Here, we report the first Miocene fossil teeth from the shoulders of the Urema Rift in Gorongosa National Park, Mozambique.

The utility of body size as a functional trait to link the past and present in a diverse reptile clade.

Understanding the relationships between functional traits and environment is increasingly important for assessing ecosystem health and forecasting biotic responses to future environmental change. Taxon-free analyses of functional traits (ecometrics) allow for testing the performance of such traits through time, utilizing both the fossil record and paleoenvironmental proxies. Here, we test the role of body size as a functional trait with respect to climate, using turtles as a model system.

gene expression predicts tetrapod-like axial regionalization in the skate, .

The axial skeleton of tetrapods is organized into distinct anteroposterior regions of the vertebral column (cervical, trunk, sacral, and caudal), and transitions between these regions are determined by colinear anterior expression boundaries of , , , and paralogy group genes within embryonic paraxial mesoderm. Fishes, conversely, exhibit little in the way of discrete axial regionalization, and this has led to scenarios of an origin of -mediated axial skeletal complexity with the evolutionary transition to land in tetrapods. Here, combining geometric morphometric analysis of vertebral column morphology with cell lineage tracing of gene expression boundaries in developing embryos, we recover evidence of at least five distinct regions in the vertebral skeleton of a cartilaginous fish, the little skate ().

Pectoral myology of limb-reduced worm lizards (Squamata, Amphisbaenia) suggests decoupling of the musculoskeletal system during the evolution of body elongation.

Background: The evolution of elongated body forms in tetrapods has a strong influence on the musculoskeletal system, including the reduction of pelvic and pectoral girdles, as well as the limbs. However, despite extensive research in this area it still remains unknown how muscles within and around bony girdles are affected by these reductions. Here we investigate this issue using fossorial amphisbaenian reptiles, or worm lizards, as a model system, which show substantial variation in the degree of reductions of girdles and limbs.

Squamate reptiles from Kanapoi: Faunal evidence for hominin paleoenvironments.

The squamate fossil record from Kanapoi reveals generic to higher-order similarities with modern East African herpetofaunas. The record is derived from surface collection and screen washing, and consists primarily of isolated vertebrae with a few maxillary and mandibular elements. The most abundant remains are vertebrae of large-bodied Python that are morphologically similar to extant Python sebae, and vertebrae of Varanus cf.

A new Late Cretaceous iguanomorph from North America and the origin of New World Pleurodonta (Squamata, Iguania).

Iguanomorpha (stem + crown Iguania) is a diverse squamate clade with members that predominate many modern American lizard ecosystems. However, the temporal and palaeobiogeographic origins of its constituent crown clades (e.g.

The Fossil Calibration Database-A New Resource for Divergence Dating.

Fossils provide the principal basis for temporal calibrations, which are critical to the accuracy of divergence dating analyses. Translating fossil data into minimum and maximum bounds for calibrations is the most important-often least appreciated-step of divergence dating. Properly justified calibrations require the synthesis of phylogenetic, paleontological, and geological evidence and can be difficult for nonspecialists to formulate.

Evolution of the snake body form reveals homoplasy in amniote Hox gene function.

Hox genes regulate regionalization of the axial skeleton in vertebrates, and changes in their expression have been proposed to be a fundamental mechanism driving the evolution of new body forms. The origin of the snake-like body form, with its deregionalized pre-cloacal axial skeleton, has been explained as either homogenization of Hox gene expression domains, or retention of standard vertebrate Hox domains with alteration of downstream expression that suppresses development of distinct regions. Both models assume a highly regionalized ancestor, but the extent of deregionalization of the primaxial domain (vertebrae, dorsal ribs) of the skeleton in snake-like body forms has never been analysed.

Unusual soft-tissue preservation of a crocodile lizard (Squamata, Shinisauria) from the green river formation (Eocene) and shinisaur relationships.

We describe an unusual squamate fossil from the Green River Formation (Uintan, Eocene) from the Piceance Creek Basin, Colorado, USA. The new specimen, USNM PAL 540708, is a small fossil squamate skin lacking skeletal elements. It is preserved as a part and counterpart in fine-grained limestone.

Giant lizards occupied herbivorous mammalian ecospace during the Paleogene greenhouse in Southeast Asia.

Mammals dominate modern terrestrial herbivore ecosystems, whereas extant herbivorous reptiles are limited in diversity and body size. The evolution of reptile herbivory and its relationship to mammalian diversification is poorly understood with respect to climate and the roles of predation pressure and competition for food resources. Here, we describe a giant fossil acrodontan lizard recovered with a diverse mammal assemblage from the late middle Eocene Pondaung Formation of Myanmar, which provides a historical test of factors controlling body size in herbivorous squamates.

Eocene lizard from Germany reveals amphisbaenian origins.

Amphisbaenia is a speciose clade of fossorial lizards characterized by a snake-like body and a strongly reinforced skull adapted for head-first burrowing. The evolutionary origins of amphisbaenians are controversial, with molecular data uniting them with lacertids, a clade of Old World terrestrial lizards, whereas morphology supports a grouping with snakes and other limbless squamates. Reports of fossil stem amphisbaenians have been falsified, and no fossils have previously tested these competing phylogenetic hypotheses or shed light on ancestral amphisbaenian ecology.

Synthesizing and databasing fossil calibrations: divergence dating and beyond.

Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3-6 March, 2011, Durham, NC, USA), bringing together palaeontologists, molecular evolutionists and bioinformatics experts to present perspectives from disciplines that generate, model and use fossil calibration data. Presentations and discussions focused on channels for interdisciplinary collaboration, best practices for justifying, reporting and using fossil calibrations and roadblocks to synthesis of palaeontological and molecular data.

Phylogeny and divergence times of filesnakes (Acrochordus): inferences from morphology, fossils and three molecular loci.

Acrochordus is a species-poor but highly distinctive aquatic snake genus currently distributed from India to the western edge of the Pacific. We provide the first phylogeny for the three extant species using Bayesian and parsimony analyses of one mitochondrial and two nuclear gene sequences. Acrochordus javanicus is strongly recovered as sister to A.

Predation upon hatchling dinosaurs by a new snake from the late Cretaceous of India.

Derived large-mouthed snakes (macrostomatans) possess numerous specializations in their skull and lower jaws that allow them to consume large vertebrate prey. In contrast, basal snakes lack these adaptations and feed primarily on small prey items. The sequence of osteological and behavioral modifications involved in the evolution of the macrostomatan condition has remained an open question because of disagreement about the origin and interrelationships of snakes, the paucity of well-preserved early snake fossils on many continental landmasses, and the lack of information about the feeding ecology of early snakes.

Homeotic effects, somitogenesis and the evolution of vertebral numbers in recent and fossil amniotes.

The development of distinct regions in the amniote vertebral column results from somite formation and Hox gene expression, with the adult morphology displaying remarkable variation among lineages. Mammalian regionalization is reportedly very conservative or even constrained, but there has been no study investigating vertebral count variation across Amniota as a whole, undermining attempts to understand the phylogenetic, ecological, and developmental factors affecting vertebral column variation. Here, we show that the mammalian (synapsid) and reptilian lineages show early in their evolutionary histories clear divergences in axial developmental plasticity, in terms of both regionalization and meristic change, with basal synapsids sharing the conserved axial configuration of crown mammals, and basal reptiles demonstrating the plasticity of extant taxa.

Giant boid snake from the Palaeocene neotropics reveals hotter past equatorial temperatures.

The largest extant snakes live in the tropics of South America and southeast Asia where high temperatures facilitate the evolution of large body sizes among air-breathing animals whose body temperatures are dependant on ambient environmental temperatures (poikilothermy). Very little is known about ancient tropical terrestrial ecosystems, limiting our understanding of the evolution of giant snakes and their relationship to climate in the past. Here we describe a boid snake from the oldest known neotropical rainforest fauna from the Cerrejón Formation (58-60 Myr ago) in northeastern Colombia.

Dissociation of somatic growth from segmentation drives gigantism in snakes.

Body size is significantly correlated with number of vertebrae (pleomerism) in multiple vertebrate lineages, indicating that change in number of body segments produced during somitogenesis is an important factor in evolutionary change in body size, but the role of segmentation in the evolution of extreme sizes, including gigantism, has not been examined. We explored the relationship between body size and vertebral count in basal snakes that exhibit gigantism. Boids, pythonids and the typhlopid genera, Typhlops and Rhinotyphlops, possess a positive relationship between body size and vertebral count, confirming the importance of pleomerism; however, giant taxa possessed fewer than expected vertebrae, indicating that a separate process underlies the evolution of gigantism in snakes.