The relationship between muscle architectural properties and hind foot drumming of African mole-rats has yet to be determined using established methodology. Therefore, the internal structure of 32 hind limb muscles was evaluated in two drumming and one non-drumming species of Bathyergidae. The muscle mass (MM), fascicle length (Lf), and angle of pennation were measured to calculate the physiological

This special issue of the Journal of Mammalian Evolution represents the proceedings from a symposium held in conjunction with the XXXI Jornadas Argentinas de Mastozoología (SAREM, La Rioja, Argentina, October 25, 2018), and entitled “El paradigma de correlación forma-función en mastozoología: un tributo a Leonard Radinsky (1937–1985).” In this introduction to the symposium proceedings, we provide a

Behavioral foraging differences are known to aid in food resource partitioning in pinniped communities, but it is not known whether skull biomechanical efficiency also contributes to dietary niche partitioning. We tested this hypothesis in a community of four sympatric species of pinnipeds that co-occur along the coast of Baja California: California sea lion (Zalophus californianus), northern elephant

Anatomy of bat genital organs has been conventionally studied by gross and microscopic observations to date. Here, we employ both histological observation and diceCT (diffusible iodine-based contrast-enhanced computed tomography) to study the detailed three-dimensional morphological structure of the male genital organs in bats, using the greater horseshoe bat, Rhinolophus ferrumequinum. This is the

Dental and craniomandibular data have been predominantly used to infer relationships among mylodontid ground sloths. Recent studies indicate the osteology of the manus also provides useful data to test phylogenetic relationships in mylodontine mylodontids. Here we provide new comparative data from the study of the manus of a member of the Scelidotheriinae, Scelidotherium Owen, 1839, based on specimens

The Miocene-Pliocene (Turolian-Ruscinian) transition represents a fundamental interval in the evolution of Euro-Mediterranean paleocommunities. In fact, the paleoenvironmental changes connected with the end of the Messinian salinity crisis are reflected by a major renewal in mammal faunal assemblages. An important bioevent among terrestrial large mammals is the dispersal of the genus Sus, which replaced

We addressed the spatiotemporal characteristics of four commensal rodent species occurring in Myanmar in comparison with other areas of the Indo-Malayan region. We examined sequence variations of the mitochondrial cytochrome b gene (Cytb) in the Pacific rat (Rattus exulans), roof rat (Rattus rattus complex, RrC), lesser bandicoot rat (Bandicota bengalensis), and house mouse (Mus musculus) using the

The caudal cranium and occipito-cervical region, although usually overlooked, are informative about the paleobiology of fossil mammals, allowing inquiry into vision and hearing abilities, as well as head and neck postures. Particularly for Pachyrukhinae, some related features remain unexplored. In this contribution, 22 specimens of Paedotherium and Tremacyllus were analyzed in a mainly qualitative

Several recent studies have suggested past gene flow between the Przewalski’s horse and modern domestic horse and questioned the wild origin of the Przewalski’s horse. Mitochondrial DNA has placed representatives of the Przewalski’s horse into three among the eighteen haplogroups detected from the modern horse. Of these, two haplogroups have so far been found exclusively in the Przewalski’s horse,

Inquiring into the paleoecology of extinct forms is always a challenge, particularly when the taxa under study correspond to derived ecomorphs of ancient and completely extinct clades. In this contribution, the configuration of the masticatory apparatus and associated features of the Neogene pachyrukhines Paedotherium and Tremacyllus are studied in a detailed, mainly qualitative, comparative analysis

We provide detailed morphological description, including enamel microstructure, of the earliest known embrithopod mammals (Afrotheria, Paenungulata), Stylolophus minor and S. major, n. sp., recently discovered in the early Eocene of the Ouled Abdoun phosphate basin, Morocco. Stylolophus minor and S. major, n. sp., show close morphological affinity, and the enamel microstructure supports their congeneric

Three species of sexually-dimorphic opossums are broadly distributed across South America: the habitat generalist Didelphis albiventris, the Atlantic forest-dweller D. aurita, and the Amazonian forest-dweller D. marsupialis. We used 2D geometric morphometrics to quantify skull size and shape variation in the three opossum species and test the hypothesis that degrees of sexual dimorphism and morphological

Commerson’s dolphin (Cephalorhynchus commersonii), Peale’s dolphin (Lagenorhynchus australis), dusky dolphin (Lagenorhynchus obscurus), and hourglass dolphin (Lagenorhynchus cruciger) are closely related species occurring in the Southern Hemisphere. Even though they are partially sympatric, they have evolved towards diverse foraging strategies, prey, and habitat preferences. Size variation occurs both

Rodents and carnivorans constitute two diverse clades with variable life habits. To analyze the common ecomorphological aspects of their limbs in relation to their different substrate uses, the shape of humerus and femur was explored using 3-D geometric morphometrics. The principal components and MANOVA analyses show that the shape of the humerus is similarly related to the substrate use and taxonomy

Lower Miocene outcrops from Patagonia (Gaiman Formation, Burdigalian) may reveal more clues for the yet unknown aspects for this period in the evolution of odontocetes. Here, we present the first toothless platanistoid dolphin from the lower Miocene of Patagonia, Dolgopolis kinchikafiforo, gen. et sp. nov. The specimen includes an incomplete skull, with no mandibles or earbones, but sufficiently different

Variation in the dentition yields insight into the evolutionary history of Mammalia. However, to date, there has been limited research on the dental variation in Pteropodidae, a family of bats found throughout sub-Saharan Africa, Southeast Asia, and Oceania. Most species are large, diurnal, non-echolocating, and eat fruit or nectar. Pteropodids are of significant concern in conservation due to rapidly

The adaptations for a particular locomotor type (e.g., fossorial or saltatorial) could affect limb bone morphology throughout ontogeny. We explore how the measurements of the forelimbs and functional indices change along the postnatal ontogeny of 92 specimens of sigmodontines belonging to four genera (Akodon, Eligmodontia, Oligoryzomys, and Oxymycterus) with different locomotor types (ambulatory,

Understanding feeding ecology of extinct kangaroos is fundamental to understanding the evolution of kangaroos and the Australia paleoenvironment during the Oligo-Miocene. Comparisons with extant species have suggested that the macropodiforms of the Oligo/Miocene (kangaroos and allies) from the Riversleigh World Heritage Area, northern Australia, were predominantly folivorous browsers or fungivores

Caviomorphs are a mainly South American rodent clade with high taxonomic and ecomorphological diversity. In this study, we combine geometric morphometric, functional, ancestral reconstruction, and macroevolutionary analyses to quantify the magnitude, direction, and rates of shape diversification of the caviomorph mandible, and to explore the morpho-functional implications and potential ecological catalysts

The mammalian neck adopts a variety of postures during daily life and generates numerous head trajectories. Despite its functional diversity, the neck is constrained to seven cervical vertebrae in (almost) all mammals. Given this low number, an unexpectedly high degree of modularity of the mammalian neck has more recently been uncovered. This work aims to review neck modularity in mammals from a developmental

The Yucatan Peninsula (YP) is a biotic province located in southeastern Mexico, delimited mainly by climatic variables. One endemic species of the YP is the Yucatan deer mouse Peromyscus yucatanicus. It is considered a member of the P. mexicanus species group, but some morphological characters and habitat preferences separate it from them. Herein, the DNA barcoding identification of P. yucatanicus

The late Miocene was a period of great radiation for the subfamily Caninae in North America. During this time, the early taxa of the two tribes of this subfamily, Vulpini and Canini, arose. Among them, Eucyon is one of the most important elements of the latest Miocene-Pliocene Canidae guild of both North America and Eurasia as they rapidly spread worldwide. The earliest member of the genus Canis, Canis

The dormice (Gliridae) represent a relatively small family of rodents, but exhibit considerable variation in their cranial anatomy. The skull morphology of almost all genera of dormice was described from osteological specimens in an earlier publication. However, the rare desert dormouse, Selevinia betpakdalaensis, was only assessed using previous descriptions and photographic images, resulting in difficulties

Understanding the interplay between morphological integration and modularity is considered an important topic in the study of the evolution of the form of complex structures. The mandible is a complex structure that can be shaped by diverse factors such as ontogeny, ecology, and evolutionary history. In canids, this is particularly interesting because they have a large diversity in feeding behavior

The dynamics of species diversification have attracted significant scientific attention in recent decades. Many lineages tend to maintain their niche characteristics over evolutionary time, a phenomenon known as phylogenetic niche conservatism (NC), which can slow the processes of ecological speciation by diversification selection. NC can, however, promote speciation through neutral evolution, favoring

Xenarthra, one of the major clades of placentals, comprises two different lineages (sloths and anteaters, and armadillos) with extant representatives showing strongly different morphologies and life habits. Sloths are arboreal herbivores, anteaters are insectivores with digging/climbing abilities, and armadillos are terrestrial diggers with varied diets. The ulna is one of the forelimb elements that

South American cervids have a relatively recent evolutionary history in the Neotropics. Present taxonomical richness includes six genera and 17 species grouped in at least two clades, Blastocerina and Odocoileina. With few exceptions, functional morphology or ecomorphological approaches have not been rigorously applied to the masticatory apparatus of Neotropical deer. In order to understand the relationship

Monotremes are a group of egg-laying mammals, possessing a mosaic of ancestral and derived anatomical features. Despite much interest in monotremes from phylogenetic, morphological, and ecological perspectives, they have been the subject of relatively few biomechanical studies. In this study, we examined shoulder and proximal forelimb muscle anatomy and architecture in the short-beaked echidna, Tachyglossus

The anthropic effect associated with worldwide European settlements over the last 500 years has caused dramatic environmental changes, modified regional patterns of biodiversity, and often led to local or complete extinctions. The sigmodontine rodents of Bahía Samborombón (Humid Pampas, central-eastern Argentina) constitute a good case study: a late Holocene archaeological site allowed us to compare

Understanding species distributions and the variation of assemblage structure in time and space are fundamental goals of biogeography and ecology. Here, we use an ecological niche modeling and macroecological approach in order to assess whether constraints patterns in carnivoran richness and composition structures in replicated assemblages through time and space should reflect environmental filtering

The diversification of anatomical structures with functional importance during the branching process of a clade is a widely studied phenomenon in evolutionary biology. In recent years, there is a growing interest in the study of the inner ear, a structure associated with hearing, locomotion, and indirectly, with body size. These studies have been particularly important in primates. The platyrrhine

Processes such as climate fluctuations together with recent volcanism have driven the diversification and local persistence of biodiversity within the Mexican highlands. We reconstruct the phylogeographic pattern and historical demography of the volcano rabbit, Romerolagus diazi, an endemic lagomorph in central Mexico, to elucidate the effect of the climate-volcanism interaction on its evolutionary

Although didelphid marsupials are considered to have a conservative body shape, they show a considerable amount of size variation. They also have different diets (from frugivore to animalivore), but none of the species are specialized. Didelphid marsupials also have a certain degree of specialization in vertical habitat use, from ground-dwellers to canopy-dwellers. Several authors have shown in other

Sthenurine kangaroos, extinct “giant kangaroos” known predominantly from the Plio-Pleistocene, have been proposed to have used bipedal striding as a mode of locomotion, based on the morphology of their hind limbs. However, sthenurine forelimb morphology has not been considered in this context, and has important bearing as to whether these kangaroos employed quadrupedal or pentapedal locomotion as a

The Tetonius-Pseudotetonius (T-P) transition is an often-cited example of phyletic gradualism, but rates of evolution and the roles of neutral and adaptive processes across this lineage remain unclear. Linking Tetonius and Pseudotetonius, two omomyid primates, are a series of stratigraphic and morphologic intermediates revealing trends suggestive of a functional and developmental reorganization of

The Old World fossil record of the family Camelidae is patchy, but a new partial cranium and some other remains of Camelus grattardi from the Mille-Logya Project area in the Afar, Ethiopia, greatly increase the fossil record of the genus in Africa. These new data – together with analysis of unpublished and recently published material from other sites, and reappraisal of poorly known taxa – allow for

Table 2 of this paper has an unnecessary value of 1.88 in the row of PIN 3101/63 (Eobaatar magnus), which is not related with this table. This is just an authors’ mistake, and please ignore this value.

Credit for the Basilosaurus tooth photograph in Figure 9a: Aaron Miller, Ancient Earth Trading Company LLC. Also, please note that individual teeth shown in both Figure 2 and Figure 9 were not the specific sources of accompanying enamel photomicrographs.

In the transition from a terrestrial to an aquatic environment, sirenian marine mammals reduced and lost their hind limbs and developed a horizontal caudal fin, the main propulsive organ in extant sirenians. Quadrupedal forms are only known from the Eocene and are represented by three different clades: the amphibious “prorastomids,” the aquatic quadrupedal protosirenids, and Sobrarbesiren cardieli

Five multituberculate species have been reported to date from the upper Lower Cretaceous (Aptian–Albian) Shahai and Fuxin formations in Liaoning Province, northeastern China. We herein describe an additional species of eobaatarid multituberculate from the Fuxin Formation, Dolichoprion lii, gen. et sp. nov., with a long (relative to height) crown of the fourth lower premolar, which is unique among eobaatarids

Hares from Iran can be divided into three morphological groups, with Lepus europaeus inhabiting the western parts of Iran. Hares from lowland areas along the southeastern corner of the Caspian Sea are morphologically similar to both L. tolai and L. tibetanus, but diagnosis is complicated by a lack of taxonomic agreement. Mitochondrial DNA suggests L. tibetanus rather than L. tolai, although comparative

A large part of the diversity of longevity and actuarial senescence (i.e., the progressive decline of survival probabilities with age) across vertebrates can be related to body size, phylogeny, and the species’ position on the slow-fast continuum of life histories. However, differences in mortality patterns between ecologically similar species, such as bovids and equids, remain poorly understood. Equids

New material of Agriotherium from the late Hemphillian (~6 Ma) Quiburis Formation in Arizona, North America is reported. These specimens represent a new species, Agriotherium hendeyi, sp. nov., of small size and with a bucco-lingually narrow lower dentition distinguishing it from North American “Agriotherium” schneideri as well as the genotype and other Old World species of Agriotherium. Strikingly

Enamel microstructure of 34 species in eight odontocete families is described and categorized according to structural complexity (from no or prismless enamel to highly arranged enamel in decussating layers), then correlated with parameters of ecology, life history, and occlusal function. Overall, more complex dental structure in extant and extinct cetaceans is associated with smaller, more numerous

We describe and discuss the morphology and functional anatomy of the thoracolumbar and sacrocaudal regions of the vertebral column of the late Miocene amphicyonid Magericyon anceps. These regions are essential for body support, and very relevant for locomotion and prey capture, and thus their study provides interesting insights on the paleobiology and biomechanics of this top predator. Magericyon anceps

“Sparassocynids” are small, carnivorously-adapted marsupials known from the late Miocene and Pliocene of South America, thought to be relatives of living didelphid opossums but of otherwise uncertain phylogenetic relationships. Here, we describe a nearly complete juvenile skull of the “sparassocynid” Sparassocynus derivatus, from the Pliocene (~5–3 million years old) Chapadmalal Formation, Argentina

Diversification and adaptive radiations are tied to evolvability, which in turn is linked to morphological integration. Tightly integrated structures typically evolve in unison, whereas loosely integrated structures evolve separately. Highly integrated structures are therefore thought to constrain evolutionary change by limiting morphological disparity. Mounting evidence suggests that high integration

Comparative morphometric study of recently recovered fossil elephant molars from Natodomeri, Kenya identifies them as belonging to Elephas jolensis and confirms the presence of this species in Members I and II of the Kibish Formation. Improved datation of these geological units constrains them between 205 and 130 ka. Elephas jolensis is also reported from localities in northern, northwestern, eastern

The sand cat, Felis margarita Loche, 1858, is a small desert cat with a fragmented distribution across the Sahara, Arabian Peninsula, and Central Asia. It is currently listed as Least Concern by the IUCN; however, its status in many countries is unknown. Sand cats are generally classified into four subspecies: F. m. margarita (North Africa and Sahara), F. m. harrisoni (Arabia), F. m. thinobia (Central

Chiroptera is the only group of mammals capable of powered flight. The mechanical basis of bat flight is well established, but evolution of its constituent aerodynamic variables remains poorly understood. Here, we determine the macroevolutionary patterns of traditional aerodynamic variables (wing loading, aspect ratio, tip shape index) in a comprehensive phylogeny of Chiroptera using an extensive dataset

As molecularly derived phylogenies have become more prominent in determining evolutionary relationships, researchers have developed multiple methods of time-calibration to estimate ages of speciation or dispersal events. These methods, however, do not always arrive at congruent node ages. Fossil evidence is one of the most common forms of calibration for phylogenies, but age estimates can vary greatly

Argyrolagus constitutes, both for its craniodental and postcranial anatomy, one of the most notably specialized South American Neogene metatherians. Differentiating it from any other South American mammal, bipedal jumping has been proposed for Argyrolagus, even though this hypothesis was not supported by morphofunctional studies. Here, we describe the postcranium of A. scaglai (from the Pliocene of

We describe here a new small bunodont metatherian from Priabonian deposits of the Geste Formation exposed in the Puna of Catamarca Province (Argentina). The material, an isolated right M2?, was recovered by screen-washing techniques and allows us to erect the new species Apeirodon sorianoi. The combination of diagnostic characters includes triangular occlusal pattern, bunoid, with an equally developed

In this contribution we describe a partial dentary with teeth and an astragalus referred to the ancient megatheriine Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) recovered from the Collón Curá Formation (Miocene) at Chubut Province, Argentina. Referral of the new specimens is based on metric and morphological similarities with the holotype and specimens that have been referred

In mammals, the infraorbital canal provides a passage for the infraorbital ramus of the maxillary branch of the trigeminal nerve. The infraorbital nerve ensures tactile sensitivity of the upper teeth and face between the eye and upper lip and, more significantly, the innervation of mystacial vibrissae (whiskers). In contrast, most non-mammalian synapsids display a more “reptilian-like” ancestral condition

Diversification of animal vocalizations plays a key role in behavioral evolution and speciation. Vocal organ morphology represents an important source of acoustic variation, yet its small size, complex shape, and absence of homologous landmarks pose major challenges to comparative analyses. Here, we use a geometric morphometric approach based on geometrically homologous landmarks to quantify shape

Xenarthra (sloths, anteaters, and armadillos) are the quintessential South American mammals. Among the xenarthrans, sloths constitute the most diverse paleontologically with almost 100 fossil genera recorded. However, this abundant sloth fauna in the Americas became extinct around 10,000 years ago. Only six species belonging to two genera, Bradypus (four three-toed sloth species) and Choloepus (two

X-ray computed tomography of the cladotherian Henkelotherium guimarotae from the Kimmeridgian Guimarota coal mine (Portugal) adds new information on its postcranial skeleton. Contrary to earlier description, the humerus of Henkelotherium shows a plesiomorphic cladotherian condition similar to that seen in Dryolestes leiriensis in having individual radial and ulnar condyles on the anterior aspect of

The pigmentation patterns of many carnivorous mammals comprise contrasting white patches of hair in different parts of the body whose evolution remains largely misunderstood. Some felids (Felidae) exhibit conspicuous white spots on the posterior part of the ears, while the ear color of others is uniform. On the basis that ear movement in felids has a role in intraspecific communication and that color

Notoungulates are an extinct clade of South American mammals, comprising a large diversity of body sizes and skeletal morphologies, and including taxa with highly specialized dentitions. The evolutionary history of notoungulates is characterized by numerous dental convergences, such as continuous growth of both molars and incisors, which repeatedly occurred in late-diverging families to counter the