BOOK REVIEWS

ABSTRACT

This paper provides our views on the areas of cetacean bioacoustics that are in the greatest need of study over the next several years. In doing this, we ask a number of questions we see as important to developing a better understanding of cetacean bioacoustics. The topics we will cover are: Auditory Capabilities, including hearing sensitivity, pathways of sound to the ear, intraspecific variation in hearing capabilities, and the effects of intense sound on hearing capabilities; Echolocation, including the information-bearing parameters exploited by dolphin sonar systems to discriminate and identify objects, and the functional characteristics of the internal representation generated by reflections from ensonified objects; and Acoustic Communication, including the nature of the cetacean sound generation mechanism, the behaviors associated with mysticete communication sounds, and the range over which mysticetes communicate. While other investigators may not fully agree with our suggestions as to which questions are most important for future studies of cetacean bioacoustics, it is clear that a considerable effort must still be made in order that we can better understand the bioacoustics and general behavior of these animals.     

Morphology of the odontocete melon and its implications for acoustic function

Toothed whales (crown Odontoceti) are unique among mammals in their ability to echolocate underwater, using specialized tissue structures. The melon, a structure composed of fat and connective tissue, is an important component in the production of an echolocation beam; it is known to focus high frequency, short duration echolocation clicks. Here, we report on the morphology of the odontocete melon to provide a comprehensive understanding of melon structure across odontocete taxa. This study examined nine odontocete species (12 individual specimens), from five of the ten extant odontocete families. We established standardized definitions using computed tomography scans of the melon to investigate structure without losing geometric integrity. The morphological features that relate to the focusing capacity of the melon include internal density topography, melon size and shape, and relationship to other forehead structures. The potential for melon structure to act as a filter is discussed: establishing a lower limit to the frequency of sounds that can be propagated through the head. Collectively, the results of this study provide a robust, quantitative and comparative framework for evaluating tissue structures that form a key component of the echolocation apparatus.     

PORPOISE CLICKS FROM A SPERM WHALE NOSE—CONVERGENT EVOLUTION OF 130 KHZ PULSES IN TOOTHED WHALE SONARS?

ABSTRACT

Small toothed whales of the family Phocoenidae and delphinid genus Cephalorhynchus produce long-duration, narrowband biosonar clicks above 100 kHz, that might be seen as an adaptation for short range echolocation in shallow water. This paper presents data showing that the distantly related, and larger pygmy sperm whale Kogia breviceps (Kogiidae), that is a deep-diving, cephalopod-eating toothed whale, produce narrow-banded high frequency (NBHF) clicks identical to those of Phocoena and Cephalorhynchus (f₀ = 130 kHz, Q_3dB>10, duration > 80 msec). Thus, NBHF biosonar signals have evolved on three independent occasions in the odontocete suborder, but the apparent functional convergence does not relate to anatomical or niche similarity. Rather, it is suggested that a biosonar strategy adapting to a minimum in ocean ambient noise above 100 kHz in concert with high Q auditory filters have led to convergent evolution of the NBHF biosonar clicks. Since these biosonar signals carry all their energy at frequencies above the upper hearing limit of the killer whale Orcinus orca, predator avoidance may also have been a evolutionary shaping factor of the sonar signals from these non-whistling odontocetes.     

Morphology of the melon and its tendinous connections to the facial muscles in bottlenose dolphins (Tursiops truncatus)

The melon is a lipid‐rich structure located in the forehead of odontocetes that functions to propagate echolocation sounds into the surrounding aquatic environment. To date, the melon's ability to guide and impedance match biosonar sounds to seawater has been attributed to its unique fatty acid composition. However, the melon is also acted upon by complex facial muscles derived from the m. maxillonasolabialis. The goal of this study was to investigate the gross morphology of the melon in bottlenose dolphins (Tursiops truncatus) and to describe how it is tendinously connected to these facial muscles. Standard gross dissection (N = 8 specimens) and serial sectioning (N = 3 specimens) techniques were used to describe the melon and to identify its connections to the surrounding muscles and blubber in three orthogonal body planes. The dolphin forehead was also thin‐sectioned in three body planes (N = 3 specimens), and polarized light was used to reveal the birefringent collagen fibers within and surrounding the melon. This study identified distinct regions of the melon that vary in shape and display locally specific muscle‐tendon morphologies. These regions include the bilaterally symmetric main body and cone and the asymmetric right and left caudal melon. This study is the first to identify that each caudal melon terminates in a lipid cup that envelopes the echolocation sound generators. Facial muscles of the melon have highly organized tendon populations that traverse the melon and insert into either the surrounding blubber, the connective tissue matrix of the nasal plug, or the connective tissue sheath surrounding the sound generators. The facial muscles and tendons also lie within multiple orthogonal body planes, which suggest that the melon is capable of complex shape change. The results of this study suggest that these muscles could function to change the frequency, beam width, and directionality of the emitted sound beam in bottlenose dolphins. The echolocation sound propagation pathway within the dolphin forehead appears to be a tunable system. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

Functional niche partitioning in Therizinosauria provides new insights into the evolution of theropod herbivory

Dietary specialization is generally considered to be a crucial factor in driving morphological evolution across extant and extinct vertebrates. The ability to adapt to a specific diet and to exploit ecological niches is thereby influenced by functional morphology and biomechanical properties. Differences in functional behaviour and efficiency can therefore allow dietary diversification and the coexistence of similarly adapted taxa. Therizinosauria, a group of secondarily herbivorous theropod dinosaurs, is characterized by a suite of morphological traits thought to be indicative of adaptations to an herbivorous diet. Digital reconstruction, theoretical modelling and computer simulations of the mandibles of therizinosaur dinosaurs provides evidence for functional niche partitioning in adaptation to herbivory. Different mandibular morphologies present in therizinosaurians were found to correspond to different dietary strategies permitting coexistence of taxa. Morphological traits indicative of an herbivorous diet, such as a downturned tip of the lower jaw and an expanded postdentary region, were identified as having stress mitigating effects. The more widely distributed occurrence of these purported herbivorous traits across different dinosaur clades suggests that these features also could have played an important role in the evolution and acquisition of herbivory in other groups.     

Computational framework to model and design surgical meshes for hernia repair

Surgical procedures for hernia surgery are usually performed using prosthetic meshes. In spite of all the improvements in these biomaterials, the perfect match between the prosthesis and the implant site has not been achieved. Thus, new designs of surgical meshes are still being developed. Previous to implantation in humans, the validity of the meshes has to be addressed, and to date experimental studies have been the gold standard in testing and validating new implants. Nevertheless, these procedures involve long periods of time and are expensive. Thus, a computational framework for the simulation of prosthesis and surgical procedures may overcome some disadvantages of the experimental methods. The computational framework includes two computational models for designing and validating the behaviour of new meshes, respectively. Firstly, the beam model, which reproduces the exact geometry of the mesh, is set to design the weave and determine the stiffness of the surgical prosthesis. However, this implies a high computational cost whereas the membrane model, defined within the framework of the large deformation hyperelasticity, is a relatively inexpensive computational tool, which also enables a prosthesis to be included in more complex geometries such as human or animal bodies.     

Sexual Dimorphism of the Larynx of the Mongolian Gazelle (Procapra gutturosa Pallas, 1777) (Mammalia, Artiodactyla, Bovidae)

The larynges (except for the epiglottis) of two adult Mongolian gazelles, one male and one female, were dissected. This species is characterized by a pronounced sexual dimorphism of the larynx. Dimorphism with regard to the size of the entire larynx and of the thyroid cartilage is about 2:1 whereas the difference of mean body mass is about 1.3:1 between males and females. Unexpectedly, and in contrast to other bovids, the larynx of the male Mongolian gazelle has a paired lateral laryngeal ventricle. However, in contrast to horse, dog, pig and many primate species also possessing such a paired ventricle, its rostral opening in the Mongolian gazelle is situated lateral to the corniculate process of the arytenoid cartilage. The neck of the laryngeal ventricle is embraced by the bifurcated cuneiform process of the epiglottis. Despite the enlarged laryngeal cartilages, the vocal process of the male arytenoid cartilage is relatively shorter than that of the female. The male thyroarytenoid muscle is clearly separated into a rostral ventricular muscle and a caudal vocal muscle whereas the female's, as in other bovids, is almost uniform. The lateral sac of the two-chambered laryngeal ventricle in the male projects laterally between the ventricular and the vocal muscle. As in the domestic bovids and in many other artiodactyls the larynx of the male Mongolian gazelle is lacking any rostrally directed membraneous portion of the vocal fold. Instead, the thick and tough bow-like vocal fold projects caudally into the infraglottic cavity and is supported by a peculiar pan-like fibroelastic pad. This resilient element, situated medial to the bipartite thyroarytenoid muscle, might be a homologue of the vocal ligament, eventually including lateral portions of the elastic cone. A fibroelastic pad is absent in the female. The resilient floor of the laryngeal vestibulum, ventral to the fibroelastic pad, is rostrally and caudally subducted by tube-like spaces. Evolutionary enlargement of the male larynx, including the vocal folds, and of the caudal portions of the vocal tract may have shifted the fundamental and formant frequencies to a lower register. The paired lateral laryngeal ventricle might produce an amplitude increase of the vocalizations assisted by differential action of the bipartite thyroarytenoid muscle. In addition, the peculiar shape, size and tough consistency of the male vocal folds may, as in roaring felids, assist in producing high amplitude and low frequency vocalizations. Perhaps the biological role of the enlarged male larynx of Procapra gutturosa has evolved in relation to its mating system. In the rutting season, dominant males establish individual territories and maintain harems. During prolonged courtship prior to mating, these males perform an acoustic display uttering loud and guttural bellows. In addition, the bulging ventral neck region of males may serve as an optical attractant for the females. Thus, the evolution of the enlarged larynx of the male Mongolian gazelle may have been favoured by sexual selection.     

Functional implications of dicynodont cranial suture morphology

Cranial suture morphology of Lystrosaurus and the generalized dicynodont Oudenodon was investigated to determine the strain environment during mastication, which in turn may indicate a difference in cranial function between the two taxa. Finite element (FE) analysis indicated that less strain accumulated in the cranium of Lystrosaurus during orthal bite simulations than in Oudenodon. Despite the overall difference in strain magnitude, moderate to high FE‐predicted strain accumulated in similar areas of the cranium of both taxa. The suture morphology in these cranial regions of Lystrosaurus and Oudenodon was investigated further by examination of histological sections and supplemented by observations of serial sections and computed tomography (CT) scans. The predominant type of strain from selected blocks of finite elements that contain sutures was determined, enabling comparison of suture morphology to strain type. Drawing from strain‐suture correlations established in extant taxa, the observed patterns of sutural morphology for both dicynodonts were used to deduce cranial function. The moderate to high compressive and tensile strain experienced by the infraorbital bar, zygomatic arch, and postorbital bar of Oudenodon and Lystrosaurus may have been decreased by small adjustive movements at the scarf sutures in those regions. Disparities in cranial suture morphology between the two taxa may reflect differences in cranial function. For instance, the tongue and groove morphology of the postorbital‐parietal suture in Oudenodon could have withstood the higher FE‐predicted tensile strain in the posterior skull roof. The scarf premaxilla‐nasal suture of Lystrosaurus provided an additional region of sutural mobility in the anterior surface of the snout, suggesting that Lystrosaurus may have employed a different biting regime than Oudenodon. The morphology of several sutures sampled in this study correlated with the FE‐predicted strain, although other cranial functional hypotheses remain to be tested. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Dolphin whistles: a functional misnomer revealed by heliox breathing

Delphinids produce tonal whistles shaped by vocal learning for acoustic communication. Unlike terrestrial mammals, delphinid sound production is driven by pressurized air within a complex nasal system. It is unclear how fundamental whistle contours can be maintained across a large range of hydrostatic pressures and air sac volumes. Two opposing hypotheses propose that tonal sounds arise either from tissue vibrations or through actual whistle production from vortices stabilized by resonating nasal air volumes. Here, we use a trained bottlenose dolphin whistling in air and in heliox to test these hypotheses. The fundamental frequency contours of stereotyped whistles were unaffected by the higher sound speed in heliox. Therefore, the term whistle is a functional misnomer as dolphins actually do not whistle, but form the fundamental frequency contour of their tonal calls by pneumatically induced tissue vibrations analogous to the operation of vocal folds in terrestrial mammals and the syrinx in birds. This form of tonal sound production by nasal tissue vibrations has probably evolved in delphinids to enable impedance matching to the water, and to maintain tonal signature contours across changes in hydrostatic pressures, air density and relative nasal air volumes during dives.     

Comparative tests of evolutionary trade-offs in a palinurid lobster acoustic system

Communication structures vary greatly in size and can be structurally and behaviorally integrated with other systems. In structurally integrated systems, dramatic changes in size may impose trade-offs with the size of neighboring structures. In spiny lobsters (Palinuridae), there is a fivefold difference in size of the antennular plate, on which sound producing apparatus is located, such that the antennular plate reaches 38% carapace length in some sound producers (Stridentes) compared to only 4% carapace length in non-sound producing spiny lobsters (Silentes). We examined whether this major variation in antennular plate size imposes trade-offs with the adjoining antennae, specifically in the context that the signal producing structures and antennae are both used in predator defense. We recorded and analyzed lobster sounds in order to test whether size increases in the acoustic morphology were correlated with production of particular signal features. Antennal and antennular plate structures were measured across the family, including both Stridentes and Silentes. Phylogenetic comparative methods were used to test for correlated evolutionary change among the structures and signal features. We analyzed the phylogenetic relationships of the Palinuridae based on morphological characters and ribosomal DNA evidence (16S, 18S and 28S nuclear and mitochondrial ribosomal RNA gene regions). We found that the number of sound pulses was positively correlated with length of the sound producing apparatus. Opposite to the predicted trade-offs, we found that the size of the antennular plate was positively correlated with size of the surrounding antennae within Stridentes. Nevertheless, when Stridentes were compared to Silentes, the latter had relatively larger antennae for a given antennular plate size than did the sound producing taxa. These results suggest that body size does not limit size increases in acoustic structures within Stridentes, however the presence and associated constructional costs of a sound producing apparatus may impose a trade-off when taxa with and without the apparatus are compared. Alternatively, since both systems are used in predator defense, this pattern may indicate greater selection for antennal force production in Silentes, which lack the additional acoustic mode of predator defense.     

Comparative finite element analysis of the cranial performance of four herbivorous marsupials

Marsupial herbivores exhibit a wide variety of skull shapes and sizes to exploit different ecological niches. Several studies on teeth, dentaries, and jaw adductor muscles indicate that marsupial herbivores exhibit different specializations for grazing and browsing. No studies, however, have examined the skulls of marsupial herbivores to determine the relationship between stress and strain, and the evolution of skull shape. The relationship between skull morphology, biomechanical performance, and diet was tested by applying the finite element method to the skulls of four marsupial herbivores: the common wombat (Vombatus ursinus), koala (Phascolarctos cinereus), swamp wallaby (Wallabia bicolor), and red kangaroo (Macropus rufus). It was hypothesized that grazers, requiring stronger skulls to process tougher food, would have higher biomechanical performance than browsers. This was true when comparing the koala and wallaby (browsers) to the wombat (a grazer). The cranial model of the wombat resulted in low stress and high mechanical efficiency in relation to a robust skull capable of generating high bite forces. However, the kangaroo, also a grazer, has evolved a very different strategy to process tough food. The cranium is much more gracile and has higher stress and lower mechanical efficiency, but they adopt a different method of processing food by having a curved tooth row to concentrate force in a smaller area and molar progression to remove worn teeth from the tooth row. Therefore, the position of the bite is crucial for the structural performance of the kangaroo skull, while it is not for the wombat which process food along the entire tooth row. In accordance with previous studies, the results from this study show the mammalian skull is optimized to resist forces generated during feeding. However, other factors, including the lifestyle of the animal and its environment, also affect selection for skull morphology to meet multiple functional demands. J. Morphol. 276:1230–1243, 2015. © 2015 Wiley Periodicals, Inc.     

Functional performance of turtle humerus shape across an ecological adaptive landscape

The concept of the adaptive landscape has been invaluable to evolutionary biologists for visualizing the dynamics of selection and adaptation, and is increasingly being used to study morpho‐functional data. Here, we construct adaptive landscapes to explore functional trade‐offs associated with variation in humerus morphology among turtles adapted to three different locomotor environments: marine, semiaquatic, and terrestrial. Humerus shape from 40 species of cryptodire turtles was quantified using a pseudolandmark approach. Hypothetical shapes were extracted in a grid across morphospace and four functional traits (strength, stride length, mechanical advantage, and hydrodynamics) measured on those shapes. Quantitative trait modeling was used to construct adaptive landscapes that optimize the functional traits for each of the three locomotor ecologies. Our data show that turtles living in different environments have statistically different humeral shapes. The optimum adaptive landscape for each ecology is defined by a different combination of performance trade‐offs, with turtle species clustering around their respective adaptive peak. Further, species adhere to pareto fronts between marine–semiaquatic and semiaquatic–terrestrial optima, but not between marine–terrestrial. Our study demonstrates the utility of adaptive landscapes in informing the link between form, function, and ecological adaptation, and establishes a framework for reconstructing turtle ecological evolution using isolated humeri from the fossil record.     

A unique feeding strategy of the extinct marine mammal Kolponomos: convergence on sabretooths and sea otters

Mammalian molluscivores feed mainly by shell-crushing or suction-feeding. The extinct marine arctoid, Kolponomos, has been interpreted as an otter-like shell-crusher based on similar dentitions. However, neither the masticatory biomechanics of the shell-crushing adaptation nor the way Kolponomos may have captured hard-shelled prey have been tested. Based on mandibular symphyseal morphology shared by Kolponomos and sabre-toothed carnivores, we hypothesize a sabretooth-like mechanism for Kolponomos prey-capture, whereby the mandible functioned as an anchor. Torque generated from jaw closure and head flexion was used to dislodge prey by prying, with prey then crushed using cheek teeth. We test this hypothesized feeding sequence using phylogenetically informed biomechanical simulations and shape analyses, and find a strongly supported, shared high mandibular stiffness in simulated prey-capture bites and mandibular shape in Kolponomos and the sabre-toothed cat Smilodon. These two distantly related taxa converged on using mandibles to anchor cranial torqueing forces when prying substrate-bound prey in the former and sabre-driving forces during prey-killing in the latter. Simulated prey-crushing bites indicate that Kolponomos and sea otters exhibit alternative structural stiffness-bite efficiency combinations in mandibular biomechanical adaptation for shell-crushing. This unique feeding system of Kolponomos exemplifies a mosaic of form-function convergence relative to other Carnivora.     

Finite element modelling of human auditory periphery including a feed-forward amplification of the cochlea

A three-dimensional finite element model is developed for the simulation of the sound transmission through the human auditory periphery consisting of the external ear canal, middle ear and cochlea. The cochlea is modelled as a straight duct divided into two fluid-filled scalae by the basilar membrane (BM) having an orthotropic material property with dimensional variation along its length. In particular, an active feed-forward mechanism is added into the passive cochlear model to represent the activity of the outer hair cells (OHCs). An iterative procedure is proposed for calculating the nonlinear response resulting from the active cochlea in the frequency domain. Results on the middle-ear transfer function, BM steady-state frequency response and intracochlear pressure are derived. A good match of the model predictions with experimental data from the literatures demonstrates the validity of the ear model for simulating sound pressure gain of middle ear, frequency to place map, cochlear sensitivity and compressive output for large intensity input. The current model featuring an active cochlea is able to correlate directly the sound stimulus in the ear canal with the vibration of BM and provides a tool to explore the mechanisms by which sound pressure in the ear canal is converted to a stimulus for the OHCs.     

Biomechanics and functional preconditions for terrestrial lifestyle in basal tetrapods,with special consideration of Tiktaalik roseae

The fossil Tiktaalik roseae from the Late Devonian induces clear definition of the biomechanical and functional preconditions for a terrestrial lifestyle including quadrupedal standing and locomotion on limbs. Therefore, we determined the internal stresses in this model organism under the influence of gravity using the finite element method. Stress patterns during symmetrical two-forelimb support result from bending of trunk and neck. During asymmetrical one-forelimb support, as occurs during terrestrial locomotion, torsional stresses are higher than those caused by bending. The observed patterns of compressive stresses correspond well with the arrangement of compression-resistant materials: vertebral column, shoulder girdle and ribs. The tensile stresses are in accordance with the arrangement of longitudinal and oblique muscles forming the body wall. Torsional stresses concentrate along the periphery of the trunk, leaving its cavity free from mechanical stresses. Theoretical mechanics indicate that the flat skull and the mobility of the neck were advantageous for lateral snapping, similar to crocodiles. The same movement on land requires sprawling and flexed forelimbs. Our results can be interpreted as explanations for the tetrapod bauplan as well as confirmation and refinement of existing hypotheses about the lifestyle at the border between water and land of this early predecessor of terrestrial tetrapods.     

Cranial functional morphology of fossil dogs and adaptation for durophagy in Borophagus and Epicyon (Carnivora,Mammalia)

Morphological specialization is a complex interplay of adaptation and constraint, as similarly specialized features often evolve convergently in unrelated species, indicating that there are universally adaptive aspects to these morphologies. The evolutionary history of carnivores offers outstanding examples of convergent specialization. Among larger predators, borophagine canids were highly abundant during the tertiary of North America and are regarded as the ecological vicars of Afro‐Eurasian hyenas. Borophaginae is an extinct group of 60+ species, the largest forms evolving robust skulls with prominently domed foreheads, short snouts, and hypertrophied fourth premolars. These specializations have been speculated to enhance bone cracking. To test the extent that the skulls of derived borophagines were adapted for producing large bite forces and withstanding the mechanical stresses associated with bone cracking relative to their nonrobust sister clades, we manipulated muscle forces in models of six canid skulls and analyzed their mechanical response using 3D finite element analysis. Performance measures of bite force production efficiency and deformation minimization showed that skulls of derived borophagines Borophagus secundus and Epicyon haydeni are particularly strong in the frontal region; maximum stresses are lower and more evenly distributed over the skull than in other canids. Frontal strength is potentially coupled with a temporalis‐driven bite to minimize cranial stress during biting in the two derived genera, as tensile stress incurred by contracting temporalis muscles is dissipated rostro‐ventrally across the forehead and face. Comparison of estimated masticatory muscle cross section areas suggests that the temporalis‐masseter ratio is not strongly associated with morphological adaptations for bone cracking in Borophagus and Epicyon; larger body size may explain relatively larger temporalis muscles in the latter. When compared with previous studies, the overall cranial mechanics of the derived borophagines is more similar to bone‐cracking hyaenids and percrocutids than to their canid relatives, indicating convergence in both morphological form and functional capability. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Morphological changes in pedal phalanges through ornithopod dinosaur evolution: a biomechanical approach

The evolution of ornithopod dinosaurs provides a well‐documented example of the transition from digitigrady to subunguligrady. During this transition, the ornithopod pes was drastically altered from the plesiomorphic dinosaurian morphology (four digits, claw‐shaped unguals, strongly concavo‐convex joints, phalanges longer than wide, excavated collateral ligament fossae, presence of sagittal ridge, and prominent processes for the attachment of tendons) to a more derived condition (tridactyly, modification of the unguals into hooves, phalanges wider and thinner than long, lack of collateral ligament fossae, loss of sagittal ridge and tendon attachment processes, relatively flattened articular surfaces). These changes are particularly noteworthy given the overall conservatism in pedal morphology seen across Dinosauria. But what are the functional consequences of these specific morphological transitions? To study them, we examine a wide range of pedal morphologies in four non‐avian dinosaurs and two birds. Our analyses of the external morphology, two‐dimensional models (using Finite Element Analysis), and internal bone structure demonstrate that this evolutionary shift was accompanied by a loss of digit mobility and flexibility. In addition, pedal posture was modified to better align the pes with the main direction of the ground reaction force, thus becoming well suited to support high loads. These conclusions can be applied to other, parallel evolutionary changes (in both dinosaurs and mammals) that involved similar transitions to a subunguligrade posture. J. Morphol, 2006. © 2006 Wiley‐Liss, Inc.     

Revising the definition of the crustacean seta and setal classification systems based on examinations of the mouthpart setae of seven species of decapods

The crustacean cuticle has numerous projections and some of these projections, the setae, have important mechanical as well as sensory functions. The setae display a wide diversity in their external morphology, which has led to great problems separating setae from other projections in the cuticle and problems in making a consistent classification system. Here, the cuticular projections on the mouthparts of seven species of decapods are examined by scanning and transmission electron microscopy. A new definition is given: a seta is an elongate projection with a more or less circular base and a continuous lumen; the lumen has a semicircular arrangement of sheath cells basally. From the details of the external morphology the mouthpart setae are divided into seven types: pappose, plumose, serrulate, serrate, papposerrate, simple and cuspidate setae, which are suggested to reflect mechanical functions and not evolutionary history. This classification system is compared with earlier systems.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 142 , 233–252.     

An interactive surgical simulation tool to assess the consequences of a partial glossectomy on a biomechanical model of the tongue

Oral cancer surgery has a negative influence on the quality of life (QOL). As a result of the complex physiology involved in oral functions, estimation of surgical effects on functionality remains difficult. We present a user-friendly biomechanical simulation of tongue surgery, including closure with suturing and scar formation, followed by an automated adaptation of a finite element (FE) model to the shape of the tongue. Different configurations of our FE model were evaluated and compared to a well-established FE model. We showed that the post-operative impairment as predicted by our model was qualitatively comparable to a patient case for five different tongue maneuvers.     

Mobile larynx in Mongolian gazelle: Retraction of the larynx during rutting barks in male Mongolian gazelle (Procapra gutturosa Pallas, 1777)

This study provides the first evidence of pronounced temporary laryngeal descent in a bovid species. An elaborate acoustic display is prominent in male courtship behavior of polygynous Mongolian gazelle. During rut, rounding up of females is accompanied by continuous head‐up barking by dominant males. Throughout the rut their evolutionarily enlarged larynx descends to a low mid‐neck resting position. In the course of each bark the larynx is additionally retracted toward the sternum by 30% of the resting vocal tract length. A geometric model of active larynx movements was constructed by combining results of video documentation, dissection, skeletonization, and behavioral observation. The considerable distance between resting position and maximal laryngeal descent suggests a backward tilting of the hyoid apparatus and an extension of the thyrohyoid connection during the retraction phase. Return to the resting position is effected by strap muscles and by the elastic recoil of the pharynx and the thyrohyoid connection. An intrapharyngeal inflation of the peculiar palatinal pharyngeal pouch of adult males is inferred from a short‐time expansion of the ventral neck region rostral to the laryngeal prominence. The neck of adult dominant males is accentuated by long gray guard hairs during the rut. The passive swinging of the heavy larynx of adult males during locomotion gives the impression of a handicap imposed on rutting males. Apparently, this disadvantage becomes outweighed by the profits for reproductive success. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.