Interspecific and intraspecific variation in grasshopper (Orthoptera: Acrididea) molar form: implications for dietary ecology.

Like many mammals, grasshoppers (infraorder Acrididea) chew using molariform structures. Despite decades of research on mammals, little is known about grasshopper molar form and how it relates to grasshopper feeding biomechanics, diet, dietary ecology and evolution. Here, we develop a method for quantifying molar form and apply it to two species of distantly related grasshoppers with different diets (, seven females; , seven females, 11 males).

Easy to gain but hard to lose: the evolution of the knee sesamoid bones in Primates-a systematic review and phylogenetic meta-analysis.

Sesamoids are variably present skeletal elements found in tendons and ligaments near joints. Variability in sesamoid size, location and presence/absence is hypothesized to enable skeletal innovation, yet sesamoids are often ignored. Three knee sesamoids-the cyamella, medial fabella and lateral fabella-are present in primates, but we know little about how they evolved, if they are skeletal innovations, or why they are largely missing from Hominoidea.

A shared pattern of midfacial bone modelling in hominids suggests deep evolutionary roots for human facial morphogenesis.

Midfacial morphology varies between hominoids, in particular between great apes and humans for which the face is small and retracted. The underlying developmental processes for these morphological differences are still largely unknown. Here, we investigate the cellular mechanism of maxillary development (bone modelling, BM), and how potential changes in this process may have shaped facial evolution.

Biomechanics in anthropology.

Biomechanics is the set of tools that explain organismal movement and mechanical behavior and links the organism to the physicality of the world. As such, biomechanics can relate behaviors and culture to the physicality of the organism. Scale is critical to biomechanical analyses, as the constitutive equations that matter differ depending on the scale of the question.

Variation in enamel mechanical properties throughout the crown in catarrhine primates.

Enamel mechanical properties vary across molar crowns, but the relationship among mechanical properties, tooth function, and phylogeny are not well understood. Fifteen primate lower molars representing fourteen taxa (catarrhine, n = 13; platyrrhine, n = 1) were sectioned in the lingual-buccal plane through the mesial cusps. Gradients of enamel mechanical properties, specifically hardness and elastic modulus, were quantified using nanoindentation from inner (near the enamel-dentine junction), through middle, to outer enamel (near the outer enamel surface) at five positions (buccal lateral, buccal cuspal, occlusal middle, lingual cuspal, lingual lateral).

Technical note: A freeware, equitable approach to dental topographic analysis.

Dental topographic analysis has proved a valuable tool for quantifying dental morphology. Established workflows often use proprietary software for pre-processing dental surfaces, rendering the method expensive and inaccessible to many. This study explores the use of freeware pre-processing alternatives.

The mechanical failure of locally manufactured prosthetic feet from the Jaffna Jaipur Centre for Disability Rehabilitation (JJCDR), Sri Lanka.

Background: The International Organization for Standardization (ISO) 10328 standards are used to verify the safety of lower limb prosthetic devices. However, the ISO 10328 tests are performed in sterile laboratory settings and do not account for environmental or sociocultural factors associated with prosthetic use. Most locally manufactured prosthetic feet from low-income and middle-income countries, which are safely used for years, do not meet these standards.

Low-cost locally manufacturable unilateral imperial external fixator for low- and middle-income countries.

Treating open fractures in long bones can be challenging and if not performed properly can lead to poor outcomes such as mal/non-union, deformity, and amputation. One of the most common methods of treating these fracture types is temporary external fixation followed by definitive fixation. The shortage of high-quality affordable external fixators is a long-recognised need, particularly in Low- and Middle-Income Countries (LMICs).

Dental macrowear reveals ecological diversity of Gorilla spp.

Size and shape variation of molar crowns in primates plays an important role in understanding how species adapted to their environment. Gorillas are commonly considered to be folivorous primates because they possess sharp cusped molars which are adapted to process fibrous leafy foods. However, the proportion of fruit in their diet can vary significantly depending on their habitats.

The effects of femoral metaphyseal morphology on growth plate biomechanics in juvenile chimpanzees and humans.

The distal femoral metaphyseal surface presents dramatically different morphologies in juvenile extant hominoids-humans have relatively flat metaphyseal surfaces when compared with the more complex metaphyseal surfaces of apes. It has long been speculated that these different morphologies reflect different biomechanical demands placed on the growth plate during locomotor behaviour, with the more complex metaphyseal surfaces of apes acting to protect the growth plate during flexed-knee behaviours like squatting and climbing. To test this hypothesis, we built subject-specific parametric finite-element models from the surface scans of the femora of five and six juveniles.

Molar biomechanical function in South African hominins and .

Diet is a driving force in human evolution. Two species of Plio-Pleistocene hominins, and , have derived craniomandibular and dental morphologies which are often interpreted as having a more biomechanically challenging diet. While dietary reconstructions based on dental microwear generally support this, they show extensive dietary overlap between species, and craniomandibular and dental biomechanical analyses can yield contradictory results.

Anthroengineering: an independent interdisciplinary field.

In recent decades, funding agencies, institutes and professional bodies have recognized the profound benefits of transdisciplinarity in tackling targeted research questions. However, once questions are answered, the previously abundant support often dissolves. As such, the long-term benefits of these transdisciplinary approaches are never fully achieved.

Cyamella (a popliteal sesamoid bone) prevalence: A systematic review, meta-analysis, and proposed classification system.

The cyamella is a rare, generally asymptomatic, knee sesamoid bone located in the proximal tendon of the popliteal muscle. Only two studies have investigated cyamella presence/absence in humans, putting ossified prevalence rates at 0.57%-1.

Unique myological changes associated with ossified fabellae: a femorofabellar ligament and systematic review of the double-headed popliteus.

Introduction: The fabella is a sesamoid bone embedded in the tendon of the lateral head of the gastrocnemius. It is the only bone in the human body to increase in prevalence in the last 100 years. As the fabella can serve as an origin/insertion for muscles, tendons, and/or ligaments (e.

The landscape of tooth shape: Over 20 years of dental topography in primates.

Diet plays an incontrovertible role in primate evolution, affecting anatomy, growth and development, behavior, and social structure. It should come as no surprise that a myriad of methods for reconstructing diet have developed, mostly utilizing the element that is not only most common in the fossil record but also most pertinent to diet: teeth. Twenty years ago, the union of traditional, anatomical analyses with emerging scanning and imaging technologies led to the development of a new method for quantifying tooth shape and reconstructing the diets of extinct primates.

Human biological variation in sesamoid bone prevalence: the curious case of the fabella.

The fabella is a sesamoid bone located in the gastrocnemius behind the lateral femoral condyle. In humans, fabellae are 3.5 times more common today than they were 100 years ago, with prevalence rates varying between and within populations.

Effects of cropping, smoothing, triangle count, and mesh resolution on 6 dental topographic metrics.

Dental topography is a widely used method for quantifying dental morphology and inferring dietary ecology in animals. Differences in methodology have brought into question the comparability of different studies. Using primate mandibular second molars, we investigated the effects of mesh preparation parameters smoothing, cropping, and triangle count/mesh resolution (herein, resolution) on six topographic variables (Dirichlet normal energy, DNE; orientation patch count rotated, OPCR; relief index, RFI; ambient occlusion, portion de ciel visible, PCV; enamel surface area, SA; tooth size) to determine the effects of smoothing, cropping, and triangle count/resolution on topographic values and the relationship between these values and diet.

Ambient occlusion and PCV (portion de ciel visible): A new dental topographic metric and proxy of morphological wear resistance.

Recently, ambient occlusion, quantified through portion de ciel visible (PCV) was introduced as a method for quantifying dental morphological wear resistance and reconstructing diet in mammals. Despite being used to reconstruct diet and investigate the relationship between dental form and function, no rigorous analysis has investigated the correlation between PCV and diet. Using a sample of platyrrhine and prosimians M2s, we show average PCV was significantly different between most dietary groups.

Fabella prevalence rate increases over 150 years, and rates of other sesamoid bones remain constant: a systematic review.

The fabella is a sesamoid bone located behind the lateral femoral condyle. It is common in non-human mammals, but the prevalence rates in humans vary from 3 to 87%. Here, we calculate the prevalence of the fabella in a Korean population and investigate possible temporal shifts in prevalence rate.

Dental topography and the diet of Homo naledi.

Though late Middle Pleistocene in age, Homo naledi is characterized by a mosaic of Australopithecus-like (e.g., curved fingers, small brains) and Homo-like (e.

Extant ape dental topography and its implications for reconstructing the emergence of early Homo.

Dental topography reflects diet accurately in several extant and extinct mammalian clades. However, dental topographic dietary reconstructions have high success rates only when closely related taxa are compared. Given the dietary breadth that exists among extant apes and likely existed among fossil hominins, dental topographic values from many species and subspecies of great apes are necessary for making dietary inferences about the hominin fossil record.

Functional and evolutionary consequences of cranial fenestration in birds.

Ostrich-like birds (Palaeognathae) show very little taxonomic diversity while their sister taxon (Neognathae) contains roughly 10,000 species. The main anatomical differences between the two taxa are in the crania. Palaeognaths lack an element in the bill called the lateral bar that is present in both ancestral theropods and modern neognaths, and have thin zones in the bones of the bill, and robust bony elements on the ventral surface of their crania.

On the Relationship Between Tooth Shape and Masticatory Efficiency: A Finite Element Study.

Dental topography has successfully linked disparate tooth shapes to distinct dietary categories, but not to masticatory efficiency. Here, the relationship between four dental topographic metrics and brittle food item breakdown efficiency during compressive biting was investigated using a parametric finite element model of a bunodont molar. Food item breakdown efficiency was chosen to represent masticatory efficiency as it isolated tooth-food item interactions, where most other categories of masticatory efficiency include several aspects of the masticatory process.

Mechanical evidence that Australopithecus sediba was limited in its ability to eat hard foods.

Australopithecus sediba has been hypothesized to be a close relative of the genus Homo. Here we show that MH1, the type specimen of A. sediba, was not optimized to produce high molar bite force and appears to have been limited in its ability to consume foods that were mechanically challenging to eat.