The Reliability of Foot and Ankle Bone and Joint Kinematics Measured With Biplanar Videoradiography and Manual Scientific Rotoscoping

The intricate motion of the small bones of the feet are critical for its diverse function. Accurately measuring the 3-dimensional (3D) motion of these bones has attracted much attention over the years and until recently, was limited to invasive techniques or quantification of functional segments using multi-segment foot models. Biplanar videoradiography and model-based scientific rotoscoping offers an exciting alternative that allows us to focus on the intricate motion of individual bones in the foot. However, scientific rotoscoping, the process of rotating and translating a 3D bone model so that it aligns with the captured x-ray images, is either semi- or completely manual and it is unknown how much human error affects tracking results. Thus, the aim of this study was to quantify the inter- and intra-operator reliability of manually rotoscoping in vivo bone motion of the tibia, talus, and calcaneus during running. Three-dimensional CT bone volumes and high-speed biplanar videoradiography images of the foot were acquired on six participants. The six-degree-of-freedom motions of the tibia, talus, and calcaneus were determined using a manual markerless registration algorithm. Two operators performed the tracking, and additionally, the first operator re-tracked all bones, to test for intra-operator effects. Mean RMS errors were 1.86 mm and 1.90° for intra-operator comparisons and 2.30 mm and 2.60° for inter-operator comparisons across all bones and planes. The moderate to strong similarity values indicate that tracking bones and joint kinematics between sessions and operators is reliable for running. These errors are likely acceptable for defining gross joint angles. However, this magnitude of error may limit the capacity to perform advanced analyses of joint interactions, particularly those that require precise (sub-millimeter) estimates of bone position and orientation. Optimizing the view and image quality of the biplanar videoradiography system as well as the automated tracking algorithms for rotoscoping bones in the foot are required to reduce these errors and the time burden associated with the manual processing

A Direct Comparison of Biplanar Videoradiography and Optical Motion Capture for Foot and Ankle Kinematics

Measuring motion of the human foot presents a unique challenge due to the large number of closely packed bones with congruent articulating surfaces. Optical motion capture (OMC) and multi-segment models can be used to infer foot motion, but might be affected by soft tissue artifact (STA). Biplanar videoradiography (BVR) is a relatively new tool that allows direct, non-invasive measurement of bone motion using high-speed, dynamic x-ray images to track individual bones. It is unknown whether OMC and BVR can be used interchangeably to analyse multi-segment foot motion. Therefore, the aim of this study was to determine the agreement in kinematic measures of dynamic activities. Nine healthy participants performed three walking and three running trials while BVR was recorded with synchronous OMC. Bone position and orientation was determined through manual scientific-rotoscoping. The OMC and BVR kinematics were co-registered to the same coordinate system, and BVR tracking was used to create virtual markers for comparison to OMC during dynamic trials. Root mean square (RMS) differences in marker positions and joint angles as well as a linear fit method (LFM) was used to compare the outputs of both methods. When comparing BVR and OMC, sagittal plane angles were in good agreement (ankle: R2 = 0.947, 0.939; Medial Longitudinal Arch (MLA) Angle: R2 = 0.713, 0.703, walking and running, respectively). When examining the ankle, there was a moderate agreement between the systems in the frontal plane (R2 = 0.322, 0.452, walking and running, respectively), with a weak to moderate correlation for the transverse plane (R2 = 0.178, 0.326, walking and running, respectively). However, root mean squared error (RMSE) showed angular errors ranging from 1.06 to 8.31° across the planes (frontal: 3.57°, 3.67°, transverse: 4.28°, 4.70°, sagittal: 2.45°, 2.67°, walking and running, respectively). Root mean square (RMS) differences between OMC and BVR marker trajectories were task dependent with the largest differences in the shank (6.0 ± 2.01 mm) for running, and metatarsals (3.97 ± 0.81 mm) for walking. Based on the results, we suggest BVR and OMC provide comparable solutions to foot motion in the sagittal plane, however, interpretations of out-of-plane movement should be made carefully

Evolution of High Trophic Diversity Based on Limited Functional Disparity in the Feeding Apparatus of Marine Angelfishes (f. Pomacanthidae)

The use of biting to obtain food items attached to the substratum is an ecologically widespread and important mode of feeding among aquatic vertebrates, which rarely has been studied. We did the first evolutionary analyses of morphology and motion kinematics of the feeding apparatus in Indo-Pacific members of an iconic family of biters, the marine angelfishes (f. Pomacanthidae). We found clear interspecific differences in gut morphology that clearly reflected a wide range of trophic niches. In contrast, feeding apparatus morphology appeared to be conserved. A few unusual structural innovations enabled angelfishes to protrude their jaws, close them in the protruded state, and tear food items from the substratum at a high velocity. Only one clade, the speciose pygmy angelfishes, showed functional departure from the generalized and clade-defining grab-and-tearing feeding pattern. By comparing the feeding kinematics of angelfishes with wrasses and parrotfishes (f. Labridae) we showed that grab-and-tearing is based on low kinematics disparity. Regardless of its restricted disparity, the grab-and-tearing feeding apparatus has enabled angelfishes to negotiate ecological thresholds: Given their widely different body sizes, angelfishes can access many structurally complex benthic surfaces that other biters likely are unable to exploit. From these surfaces, angelfishes can dislodge sturdy food items from their tough attachments. Angelfishes thus provide an intriguing example of a successful group that appears to have evolved considerable trophic diversity based on an unusual yet conserved feeding apparatus configuration that is characterized by limited functional disparity

Feeding ecomorphology in angelfishes, f. Pomacanthidae: the implications of functional innovations on prey-dislodgement in biting reef fishes

On coral reefs, biting teleosts form a major component of reef fish assemblages. Nevertheless, they have been largely overlooked in functional research, while their ramsuction feeding counterparts have received considerable attention over the past few decades. This thesis therefore examines the functional basis of biting in coral reef fishes, with a focus on the marine angelfishes (f. Pomacanthidae), and other deep-bodied squamipinnid fishes. To evaluate the magnitude and role of functional specialisation associated with prey-capture in angelfishes, a basal species, Pomacanthus semicirculatus (Cuvier, 1931) was selected as a model taxon for comprehensive functional analysis. The feeding apparatus of Pomacanthus contains two biomechanical mechanisms of particular interest: an intramandibular joint, and a suspensorial linkage with two novel points of flexion. Preycapture kinematics were quantified using motion analysis of high-speed video, generating performance profiles to illustrate timing of onset, duration and magnitude of movement in the novel mechanisms. Mandible depression and suspensorial rotation coincide during jaw protrusion, and augment mandible protrusion to increase head length typically by 30%. Jaw closure at peak jaw protrusion appears to result from contraction of the adductor mandibulae segment A2, the only segment with insertions facilitating rotation of the dentary by approx. 30º relative to the articular. Feeding events are concluded by a highvelocity jaw retraction typically lasting 20-50 ms, and completed in 450-750 msec. Pomacanthus feeding morphology and kinematics differ from other biting teleosts, and more closely resemble some long-jawed ram-suction feeders, with the novel feeding kinematics matching an unusual diet of structurally resilient and firmly attached prey. Ten angelfish species representing all phylogenetic lineages were chosen from the GBR fauna, in order to analyse morphological and kinematic disparity in the angelfish feeding apparatus. Angelfish cranial architecture exhibits remarkable evolutionary stability with constructional changes restricted to key suspensorial specialisations governing increased jaw protrusibility, differential jaw protrusion angles and variations in alimentary tract morphology. Whilst it was previously suggested that intramandibular joints increase mechanical complexity and expand jaw-gape, in angelfishes the joint is a synapomorphy with novel gape-restricting kinematics. Individual means of the 32 most informative kinematics variables in Pomacanthus were extracted from high-speed video of feeding events. Concordant with phylogenetic evidence, the derived pygmy-angel subgenera, Centropyge [Centropyge] and C. [Xiphypops] differ significantly in several traits, whereas the basal Pomacanthus subgenera are largely indistinguishable. The monotypic Pygoplites exhibits the most pronounced flexion and Genicanthus consistently demonstrate the most restricted flexion in most variables measured. Mapping of informative alimentary traits to a phylogeny delineated divergent angelfish feeding guilds. Grab-and-tearing omnivory on sponges and other sturdy prey is utilised by several large and robust taxa and constitutes the basal trophic guild. More gracile, biting omnivory is commonly utilised in derived pygmy-angel taxa, while dislodging herbivory arose both in the basal large-bodied P. [Euxiphipops] and in the derived C. [Xiphypops]; planktivory in Genicanthus is atavistic. Gape-restricting intramandibular flexion, suspensorial rotation augmenting lower jaw protrusion and a high-velocity jaw retraction are important functional innovations with major implications for angelfish feeding morphology and kinematics. Coupled with distinct size differences amongst taxa, these traits form the functional basis for a considerable ecological diversification in angelfishes. The functional basis of biting in reef fishes was investigated in 11 deep-bodied families, to examine the relationships between novel intramandibular joints and associated trophic ecology. The results suggest convergent intramandibular joint evolution leading to biting strategies in at least five families. Restricted flexion repeatedly coincides with functional reversion to zoo-planktivory while basal ram-suction feeders generally lack flexion. In angelfishes, intramandibular joints are symplesiomorphic and evolutionarily stable, exhibiting limited kinematic divergence, averaging flexion of 27±11.1º and causing jaw occlusion at peak protrusion. Angelfish kinematics contrast with all other intramandibular joint bearers, in which gape-expanding flexion concludes prior to jawclosure. Intramandibular flexion and transition from ram-suction to biting in butterflyfishes coincide, with flexion magnitude, culminating in the crown-group of Corallochaetodon (16±6.6º) and Citharoedus (49±2.7º). Character mapping and optimisation revealed that up to seven intramandibular flexion transitions/reversals consistently correspond with trophic transitions from freeliving to attached prey. Whilst functional patterns reflect convergence of this joint, the evolutionary origin of intramandibular flexion in the squamipinnid fishes remains ambiguous. Nevertheless, a complex evolutionary history appears to have led to widespread intramandibular joint occurrence in extant biting groups, suggesting that this is a major functional innovation, and a functional prerequisite to biting in many reef fish taxa. In summary, the functional innovations of the angelfish feeding apparatus allow these fishes to pass ecological thresholds and exploit novel trophic strategies, using graband- tearing for herbivory and spongivory. Intramandibular joints appear to have been an important functional innovation, playing a similar role in driving the ecological diversification of the squamipinnes as the pharyngeal jaw apparatus in the Labroidei. However, an emerging trend of reduced feeding apparatus disparity in biters, when compared to ram-suction feeding taxa, supports the theory that novel traits can pose constraints on functional diversification. The results herein illustrate the utility of direct performance testing in quantifying disparity patterns at the organismal and assemblagelevel and emphasise the potential for combining ecomorphological and biomechanical techniques in elucidating the functional basis of the biting feeding mode

Feeding ecomorphology in angelfishes, f.\ud Pomacanthidae: the implications of functional\ud innovations on prey-dislodgement in biting reef fishes

On coral reefs, biting teleosts form a major component of reef fish assemblages.\ud Nevertheless, they have been largely overlooked in functional research, while their ramsuction\ud feeding counterparts have received considerable attention over the past few\ud decades. This thesis therefore examines the functional basis of biting in coral reef fishes,\ud with a focus on the marine angelfishes (f. Pomacanthidae), and other deep-bodied\ud squamipinnid fishes.\ud To evaluate the magnitude and role of functional specialisation associated with\ud prey-capture in angelfishes, a basal species, Pomacanthus semicirculatus (Cuvier, 1931)\ud was selected as a model taxon for comprehensive functional analysis. The feeding\ud apparatus of Pomacanthus contains two biomechanical mechanisms of particular interest:\ud an intramandibular joint, and a suspensorial linkage with two novel points of flexion. Preycapture\ud kinematics were quantified using motion analysis of high-speed video, generating\ud performance profiles to illustrate timing of onset, duration and magnitude of movement in\ud the novel mechanisms. Mandible depression and suspensorial rotation coincide during jaw\ud protrusion, and augment mandible protrusion to increase head length typically by 30%.\ud Jaw closure at peak jaw protrusion appears to result from contraction of the adductor\ud mandibulae segment A2, the only segment with insertions facilitating rotation of the\ud dentary by approx. 30º relative to the articular. Feeding events are concluded by a highvelocity\ud jaw retraction typically lasting 20-50 ms, and completed in 450-750 msec.\ud Pomacanthus feeding morphology and kinematics differ from other biting teleosts, and more closely resemble some long-jawed ram-suction feeders, with the novel feeding\ud kinematics matching an unusual diet of structurally resilient and firmly attached prey.\ud Ten angelfish species representing all phylogenetic lineages were chosen from the\ud GBR fauna, in order to analyse morphological and kinematic disparity in the angelfish\ud feeding apparatus. Angelfish cranial architecture exhibits remarkable evolutionary stability\ud with constructional changes restricted to key suspensorial specialisations governing\ud increased jaw protrusibility, differential jaw protrusion angles and variations in alimentary\ud tract morphology. Whilst it was previously suggested that intramandibular joints increase\ud mechanical complexity and expand jaw-gape, in angelfishes the joint is a synapomorphy\ud with novel gape-restricting kinematics. Individual means of the 32 most informative\ud kinematics variables in Pomacanthus were extracted from high-speed video of feeding\ud events. Concordant with phylogenetic evidence, the derived pygmy-angel subgenera,\ud Centropyge [Centropyge] and C. [Xiphypops] differ significantly in several traits, whereas\ud the basal Pomacanthus subgenera are largely indistinguishable. The monotypic Pygoplites\ud exhibits the most pronounced flexion and Genicanthus consistently demonstrate the most\ud restricted flexion in most variables measured.\ud Mapping of informative alimentary traits to a phylogeny delineated divergent\ud angelfish feeding guilds. Grab-and-tearing omnivory on sponges and other sturdy prey is\ud utilised by several large and robust taxa and constitutes the basal trophic guild. More\ud gracile, biting omnivory is commonly utilised in derived pygmy-angel taxa, while\ud dislodging herbivory arose both in the basal large-bodied P. [Euxiphipops] and in the\ud derived C. [Xiphypops]; planktivory in Genicanthus is atavistic. Gape-restricting\ud intramandibular flexion, suspensorial rotation augmenting lower jaw protrusion and a high-velocity jaw retraction are important functional innovations with major implications for\ud angelfish feeding morphology and kinematics. Coupled with distinct size differences\ud amongst taxa, these traits form the functional basis for a considerable ecological\ud diversification in angelfishes.\ud The functional basis of biting in reef fishes was investigated in 11 deep-bodied\ud families, to examine the relationships between novel intramandibular joints and associated\ud trophic ecology. The results suggest convergent intramandibular joint evolution leading to\ud biting strategies in at least five families. Restricted flexion repeatedly coincides with\ud functional reversion to zoo-planktivory while basal ram-suction feeders generally lack\ud flexion. In angelfishes, intramandibular joints are symplesiomorphic and evolutionarily\ud stable, exhibiting limited kinematic divergence, averaging flexion of 27±11.1º and causing\ud jaw occlusion at peak protrusion. Angelfish kinematics contrast with all other\ud intramandibular joint bearers, in which gape-expanding flexion concludes prior to jawclosure.\ud Intramandibular flexion and transition from ram-suction to biting in butterflyfishes\ud coincide, with flexion magnitude, culminating in the crown-group of Corallochaetodon\ud (16±6.6º) and Citharoedus (49±2.7º).\ud Character mapping and optimisation revealed that up to seven intramandibular\ud flexion transitions/reversals consistently correspond with trophic transitions from freeliving\ud to attached prey. Whilst functional patterns reflect convergence of this joint, the\ud evolutionary origin of intramandibular flexion in the squamipinnid fishes remains\ud ambiguous. Nevertheless, a complex evolutionary history appears to have led to\ud widespread intramandibular joint occurrence in extant biting groups, suggesting that this is\ud a major functional innovation, and a functional prerequisite to biting in many reef fish taxa. In summary, the functional innovations of the angelfish feeding apparatus allow\ud these fishes to pass ecological thresholds and exploit novel trophic strategies, using graband-\ud tearing for herbivory and spongivory. Intramandibular joints appear to have been an\ud important functional innovation, playing a similar role in driving the ecological\ud diversification of the squamipinnes as the pharyngeal jaw apparatus in the Labroidei.\ud However, an emerging trend of reduced feeding apparatus disparity in biters, when\ud compared to ram-suction feeding taxa, supports the theory that novel traits can pose\ud constraints on functional diversification. The results herein illustrate the utility of direct\ud performance testing in quantifying disparity patterns at the organismal and assemblagelevel\ud and emphasise the potential for combining ecomorphological and biomechanical\ud techniques in elucidating the functional basis of the biting feeding mode

Advances in the study of bat flight: the wing and the wind

Bats are diverse, speciose, and inhabit most of earth’s habitats, aided by powered flapping flight. The many traits that enable flight in these mammals have long attracted popular and research interest, but recent technological and conceptual advances have provided investigators with new kinds of information concerning diverse aspects of flight biology. As a consequence of these new data, our understanding of how bats fly has begun to undergo fundamental changes. Physical and neural science approaches are now beginning to inform understanding of structural architecture of wings. High speed videography is dramatically expanding documentation of how bats fly. Experimental fluid dynamics and innovative physiological techniques profoundly influence how we interpret the ways bats produce aerodynamic forces as they execute distinctive flight behaviors and the mechanisms that underlie flight energetics. Here, we review how recent bat flight research has provided significant new insights into several important aspects of bat flight structure and function. We suggest that information coming from novel approaches offer opportunities to interconnect studies of wing structure, aerodynamics, and physiology more effectively, and to connect flight biology to newly emerging studies of bat evolution and ecology.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Prey-capture in Pomacanthus semicirculatus (Teleostei, Pomacanthidae): functional implications of intramandibular joints in marine angelfishes

We examined prey-capture morphology and kinematics in the angelfish, Pomacanthus semicirculatus (Cuvier 1931), to evaluate the magnitude and role of functional specialisation. The feeding apparatus of P. semicirculatus possess three biomechanical mechanisms of particular interest: (1) a novel intramandibular joint, permitting dentary rotation and protruded jaw closure; (2) an opercular linkage facilitating mandible depression; and (3) a suspensorial linkage with two novel points of flexion, permitting anterior rotation of the suspensorium and augmenting mandible protrusion. Prey-capture kinematics were quantified using motion analysis of high-speed video, yielding performance profiles illustrating timing of onset, duration and magnitude of movement in these three biomechanical systems, and other variables traditionally quantified in studies of teleostean ram–suction feeding activity. Mandible depression and suspensorial rotation both augmented mandible protrusion, and coincided during jaw protrusion, typically increasing head length by 30%. Jaw closure appeared to result from contraction of the adductor mandibulae segment A2, which rotated the dentary by approximately 30° relative to the articular. This resulted in jaw closure with the mandible fully depressed and the jaws at peak-protrusion. Feeding events were concluded by a high-velocity jaw retraction (20–50 ms), and completed in 450–750 ms. Feeding kinematics and morphology of Pomacanthus differed from other biting teleosts, and more closely resemble some long-jawed ram–suction feeders. The structural and functional modifications in the Pomacanthus feeding apparatus are matched to an unusual diet of structurally resilient and firmly attached benthic prey

Evolution and biogeography of marine angelfishes (Pisces: Pomacanthidae)

Phylogenetic relationships among angelfishes (Pomacanthidae) and their putative sister taxon, the butterflyfishes (Chaetodontidae), were examined using 12S and 16S mitochondrial DNA sequences. ML and MP trees were highly congruent with good basal resolution. Monophyly of the two families was supported, although a clade comprising the Chaetodontidae and one of the outgroups, the Scatophagidae, formed the sister clade to the Pomacanthidae. All genera and subgenera within the Pomacanthidae were examined. The relationships among the 24 representative species were consistent with traditional generic boundaries, with the exception of the genus Centropyge, but differed from previous phylogenies. Estimated ages of divergence based on trans-isthmian pairs were compared with independent fossil evidence. Trans-isthmian estimates were highly conservative, while fossil-calibrated estimates were most consistent with available evidence. Fossil calibrated estimates suggest that the family has been impacted by both the Terminal Tethyan Event and the closure of the Isthmus of Panama. Within the family, ecological diversity and species-level diversification are restricted primarily to a single pygmy angelfish clade with an origin near the Oligocene–Miocene boundary