14 research outputs found
3D Morphometric and Posture Study of Felid Scapulae Using Statistical Shape Modelling
We present a three dimensional (3D) morphometric modelling study of the scapulae of Felidae, with a focus on the correlations between forelimb postures and extracted scapular shape variations. Our shape modelling results indicate that the scapular infraspinous fossa becomes larger and relatively broader along the craniocaudal axis in larger felids. We infer that this enlargement of the scapular fossa may be a size-related specialization for postural support of the shoulder joint
Three-Dimensional Geometric Analysis of Felid Limb Bone Allometry
Studies of bone allometry typically use simple measurements taken in a small number of locations per bone; often the midshaft diameter or joint surface area is compared to body mass or bone length. However, bones must fulfil multiple roles simultaneously with minimum cost to the animal while meeting the structural requirements imposed by behaviour and locomotion, and not exceeding its capacity for adaptation and repair. We use entire bone volumes from the forelimbs and hindlimbs of Felidae (cats) to investigate regional complexities in bone allometry.Computed tomographic (CT) images (16435 slices in 116 stacks) were made of 9 limb bones from each of 13 individuals of 9 feline species ranging in size from domestic cat (Felis catus) to tiger (Panthera tigris). Eleven geometric parameters were calculated for every CT slice and scaling exponents calculated at 5% increments along the entire length of each bone. Three-dimensional moments of inertia were calculated for each bone volume, and spherical radii were measured in the glenoid cavity, humeral head and femoral head. Allometry of the midshaft, moments of inertia and joint radii were determined. Allometry was highly variable and related to local bone function, with joint surfaces and muscle attachment sites generally showing stronger positive allometry than the midshaft.Examining whole bones revealed that bone allometry is strongly affected by regional variations in bone function, presumably through mechanical effects on bone modelling. Bone's phenotypic plasticity may be an advantage during rapid evolutionary divergence by allowing exploitation of the full size range that a morphotype can occupy. Felids show bone allometry rather than postural change across their size range, unlike similar-sized animals
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Aracaniform Swimming: A Proposed New Category of Swimming Mode in Bony Fishes (Teleostei: Tetraodontiformes: Aracanidae).
The deepwater boxfishes of the family Aracanidae are the phylogenetic sister group of the shallow-water, generally more tropical boxfishes of the family Ostraciidae. Both families are among the most derived groups of teleosts. All members of both families have armored bodies, the forward 70% of which are enclosed in rigid bony boxes (carapaces). There is substantial intragroup variation in both groups in body shapes, sizes, and ornamentation of the carapaces. Swimming-related morphology, swimming mode, biomechanics, kinematics, and hydrodynamics have been studied in detail in multiple species of the ostraciids. Ostraciids are all relatively high-performance median and paired fin swimmers. They are highly maneuverable. They swim rectilinearly with substantial dynamic stability and efficiency. Aracanids have not been previously studied in these respects. This article describes swimming-related aspects of morphology, swimming modes, biomechanics, and kinematics in two south Australian species (striped cowfish and ornate cowfish) that are possibly representative of the entire group. These species differ morphologically in many respects, both from each other and from ostraciids. There are differences in numbers, sizes, and placements of keels on carapaces. The most important differences from ostraciids are openings in the posterior edges of the carapaces behind the dorsal and anal fins. The bases of those fins in ostraciids are enclosed in bone. The openings in aracanids free the fins and tail to move. As a result, aracanids are body and caudal fin swimmers. Their overall swimming performances are less stable, efficient, and effective. We propose establishing a new category of swimming mode for bony fishes called "aracaniform swimming.
Sketch of a forelimb with different sizes of infraspinous fossa (dotted red sketch is for larger animal).
<p>Sketch of a forelimb with different sizes of infraspinous fossa (dotted red sketch is for larger animal).</p
The first four MVs of the ‘without size’ SSM (model with
<p><b>is in purple; model with </b><b>is in green).</b> A: 1<sup>st</sup> MV; B: 2<sup>nd</sup> MV; C: 3<sup>rd</sup> MV; D: 4<sup>th</sup> MV.</p
Moment arm from the most proximal point of humerus to the presumed vertical vector of the ground reaction force (GRF measured at FF).
<p>Moment arm from the most proximal point of humerus to the presumed vertical vector of the ground reaction force (GRF measured at FF).</p
Sketches of scapular fossa when changing size uniformly and accordingly as the first MV of the ‘with size’ SSM.
<p>The original fossa is in dashed black; the fossa by changing size uniformly is dashed red, and the fossa by changing size accordingly as the first MV of the ‘with size’ SSM is in solid black.</p
Establishing correspondences between reference (in pink) and target shape (in yellow).
<p>A: original position; B: align reference and target shapes; C: reference shape deformed to target shape.</p
Change rates of parameter values for the first four MVs in the ‘without size’ SSM.
<p>Change rates of parameter values for the first four MVs in the ‘without size’ SSM.</p