Biology subjects

Hutchinson, J. R.

Publications and source records attributed to Hutchinson, J. R..

6 recordsLinked to original sources

bioRxiv2025

Soft tissue constraints on joint mobility in the avian shoulder

Joints and their surrounding soft tissues facilitate and restrict vertebrate skeletal motion. Measures of maximal joint mobility provide insight into articular function and its limits on potential joint motion and thereby behaviour. In extinct vertebrates the reconstruction of joint mobility permits us to decipher shifts in locomotor evolution. Such measurements are generally limited to studies of osteological joint mobility. However, only a subset of osteologically feasible poses are biologically feasible because true joint mobility is limited by soft tissues, such as ligaments, that seldomly preserve in the fossil record. To address this issue, we implemented an in silico model to simulate avian glenohumeral (shoulder) movement and the constraints imposed by six ligaments on its joint mobility. We evaluated our in silico model of the partridge shoulder joint with measured ex vivo shoulder mobility using X-ray Reconstruction of Moving Morphology (XROMM). Our results indicate that modelling ligamentous constraints is integral to accurately quantifying shoulder function due to the role of ligaments in maintaining articular contact during complex glenohumeral motion. Our approach enables more confident estimates of functional joint mobility in both extant and extinct vertebrates and thereby stands to improve inferences of behaviour and musculoskeletal function in the vertebrate fossil record.

evolutionary biology↗

bioRxiv2024

Hindlimb kinematics, kinetics, and muscle dynamics during sit-to-stand and sit-to-walk transitions in emus (Dromaius novaehollandiae)

Animals not only need to walk and run but also lie prone to rest and then stand up. Sit-to-stand (STS) and sit-to-walk (STW) transitions are vital behaviours little studied in species other than humans so far, but likely impose biomechanical constraints on limb design because they involve near-maximal excursions of limb joints that should require large length changes and force production from muscles. By integrating data from experiments into musculoskeletal simulations, we analysed joint motions, ground reaction forces, and muscle dynamics during the STS and STW transitions in a large terrestrial, bipedal, and cursorial bird: the emu (Dromaius novaehollandiae, [~] 30 kg). Simulation results suggest that in both STS and STW, emus operate near the functional limits ([~] 50 % of shortening/lengthening) of some of their hindlimb muscles, particularly in distal muscles with limited capacity for length change and leverage. Both movements involved high muscle activations (> 50 %) and force generation of major joint extensor muscles early in the transition. STW also required larger net joint moments and non-sagittal motions, entailing greater demands for muscle capacity. Whilst our study involves multiple assumptions, our findings lay the groundwork for future studies to understand, for example, how tendon contributions may reduce excessive muscle demands, especially in the distal hindlimb. As the first investigation into how an avian species stands up, this study provides a foundational framework for future comparative studies investigating organismal morphofunctional specialisations and evolution, offering potential robotics and animal welfare applications. Summary statementThe study demonstrates the dynamics, biomechanical constraints, and musculotendinous control strategies during the sit-to-stand/walk transitions for a large bipedal bird - the emu - informing morphology, evolution, and potential robotic applications.

zoology↗

bioRxiv2024

Unlocking the secrets of kangaroo locomotor energetics: Postural adaptations underpin increased tendon stress in hopping kangaroos

Hopping kangaroos exhibit remarkably little change in their rate of metabolic energy expenditure with locomotor speed compared to other running animals. This phenomenon may be related to greater elastic energy savings due to increasing tendon stress; however, the mechanisms which enable the rise in stress without additional muscle work remain poorly understood. In this study, we created a three-dimensional (3D) kangaroo musculoskeletal model, integrating 3D motion capture and force plate data, to analyse the kinematics and kinetics of hopping red and grey kangaroos. Using our model, we evaluated how body mass and speed influence (i) hindlimb posture, (ii) effective mechanical advantage (EMA), (iii) the associated tendon stress in the ankle extensors, and (iv) ankle work during hopping. We found that increasing ankle dorsiflexion and metatarsophalangeal plantarflexion likely played an important role in decreasing ankle EMA by altering both the muscle and external moment arms, which subsequently increased energy absorption and peak tendon stress at the ankle. Surprisingly, kangaroo hindlimb posture changes appeared to contribute to increased tendon stress, allowing more elastic energy storage at faster speeds. These posture-mediated increases in elastic energy storage and return could be a key factor enabling kangaroos to achieve energetic benefits at faster hopping speeds, but may limit the performance of large kangaroos due to the risk of tendon rupture.

zoology↗

bioRxiv2018

Evolutionary parallelisms of pectoral and pelvic network-anatomy from fins to limbs

Pectoral and pelvic lobe-fins transformed into fore- and hindlimbs during the Devonian period, enabling the water-to-land transition in tetrapods. In the timespan of ~60 million years, transitional forms evolved, spanning a wide range of morphologies. Here we traced the evolution of well-articulated appendicular skeletons across the fins-to-limbs transition, using a network-based approach and phylogenetic tools to quantify and compare topological features of skeletal anatomy of fins and limbs. We show that the topological arrangement of bones in the pectoral and pelvic appendages evolved in parallel during the fins-to-limbs transition, occupying overlapping regions of the morphospace, following a directional mode of evolution, and decreasing their disparity over time. We identify the presence of digits as the morphological novelty triggering significant topological changes that clearly discriminated limbs from fins. The origin of digits caused an evolutionary shift towards appendages that were less densely and heterogeneously connected, but more assortative and modular. Topological disparity likewise decreased for both appendages: for the pectoral appendage, until the origin of amniotes; for the pelvic appendage, until a time concomitant with the earliest-known tetrapod tracks. Finally, we tested and rejected the presence of a pectoral-pelvic similarity bottleneck for the network-anatomy of appendages at the origin of tetrapods. We interpret our findings in the context of a dynamic compromise between possibly different functional demands in pectoral and pelvic appendages during the water-to-land transition and a shared developmental program constraining the evolvability of limbs.

evolutionary biology↗

bioRxiv2018

Limb bone scaling in hopping diprotodonts and quadrupedal artiodactyls

Bone adaptation is modulated by the timing, direction, rate, and magnitude of mechanical loads. To investigate whether frequent slow, or infrequent fast, gaits could dominate bone adaptation to load, we compared scaling of the limb bones from two mammalian herbivore clades that use radically different high-speed gaits, bipedal hopping (suborder Macropodiformes; kangaroos and kin) and quadrupedal galloping (order Artiodactyla; goats, deer and kin). Forelimb and hindlimb bones were collected from 20 artiodactyl and 15 macropod species (body mass M 1.05 - 1536 kg) and scanned in computed tomography or X- ray microtomography. Second moment of area (Imax) and bone length (l) were measured. Scaling relations (y = axb) were calculated for l vs M for each bone and for Imax vs M and Imax vs l for every 5% of length. Imax vs M scaling relationships were broadly similar between clades despite the macropod forelimb being nearly unloaded, and the hindlimb highly loaded, during bipedal hopping. Imax vs l and l vs M scaling were related to locomotor and behavioural specialisations. Low-intensity loads may be sufficient to maintain bone mass across a wide range of species. Occasional high-intensity gaits might not break through the load sensitivity saturation engendered by frequent low-intensity gaits.

evolutionary biology↗

bioRxiv2017

Secondary Osteons Scale Allometrically In Mammalian Humerus And Femur

Intra-cortical bone remodelling is a cell-driven process that replaces existing bone tissue with new bone tissue in the bone cortex, leaving behind histological features called secondary osteons. While the scaling of bone dimensions on a macroscopic scale is well known, less is known about how the spatial dimensions of secondary osteons vary in relation to the adult body size of the species. We measured the cross-sectional area of individual intact secondary osteons and their central Haversian canals in transverse sections from 40 stylopodal bones of 39 mammalian species. Scaling analysis of our data shows that mean osteonal resorption area (negative allometry, exponent 0.23, R2 0.54, p < 0.005) and Haversian canal area (negative allometry, exponent 0.34, R2 0.45, p < 0.005) are significantly related to body mass, independent of phylogeny. This study is the most comprehensive of its kind to date, and allows us to describe overall trends in the scaling behaviour of secondary osteon dimensions, supporting the inference that osteonal resorption area may be limited by the need to avoid fracture in smaller mammalian species, but the need to maintain osteocyte viability in larger mammalian species.

zoology↗