Morphometric models for estimating bite force in Mus and Rattus: mandible shape and size perform better than lever-arm ratios

ABSTRACTPrevious studies based on two-dimensional methods have suggested that the great morphological variability of cranial shape in domestic dogs has impacted bite performance. Here, we used a three-dimensional biomechanical model based on dissection data to estimate the bite force of 47 dogs of various breeds at several bite points and gape angles. In vivo bite force for three Belgian shepherd dogs was used to validate our model. We then used three-dimensional geometric morphometrics to investigate the drivers of bite force variation and to describe the relationships between the overall shape of the jaws and bite force. The model output shows that bite force is rather variable in dogs and that dogs bite harder on the molar teeth and at lower gape angles. Half of the bite force is determined by the temporal muscle. Bite force also increased with size, and brachycephalic dogs showed higher bite forces for their size than mesocephalic dogs. We obtained significant covariation between the shape of the upper or lower jaw and absolute or residual bite force. Our results demonstrate that domestication has not resulted in a disruption of the functional links in the jaw system in dogs and that mandible shape is a good predictor of bite force.

Download Full-text

Caecilian jaw-closing mechanics: integrating two muscle systems

Journal of The Royal Society Interface ◽

10.1098/rsif.2008.0155 ◽

2008 ◽

Vol 5 (29) ◽

pp. 1491-1504 ◽

Cited By ~ 20

Author(s):

Thomas Kleinteich ◽

Alexander Haas ◽

Adam P Summers

Keyword(s):

Bite Force ◽

Cross Sectional Area ◽

Sectional Area ◽

Cross Sectional ◽

Lever Arm ◽

Mandibular Joint ◽

Wide Range ◽

Jaw Joint ◽

Muscle Groups ◽

Using Data

Caecilians (Lissamphibia: Gymnophiona) are unique among vertebrates in having two sets of jaw-closing muscles, one on either side of the jaw joint. Using data from high-resolution X-ray radiation computed tomography scans, we modelled the effect of these two muscle groups ( mm. levatores mandibulae and m. interhyoideus posterior ) on bite force over a range of gape angles, employing a simplified lever arm mechanism that takes into account muscle cross-sectional area and fibre angle. Measurements of lever arm lengths, muscle fibre orientations and physiological cross-sectional area of cranial muscles were available from three caecilian species: Ichthyophis cf. kohtaoensis ; Siphonops annulatus ; and Typhlonectes natans . The maximal gape of caecilians is restricted by a critical gape angle above which the mm. levatores mandibulae will open the jaw and destabilize the mandibular joint. The presence of destabilizing forces in the caecilian jaw mechanism may be compensated for by a mandibular joint in that the fossa is wrapped around the condyle to resist dislocation. The caecilian skull is streptostylic; the quadrate–squamosal complex moves with respect to the rest of the skull. This increases the leverage of the jaw-closing muscles. We also demonstrate that the unusual jaw joint requires streptostyly because there is a dorsolateral movement of the quadrate–squamosal complex when the jaw closes. The combination of the two jaw-closing systems results in high bite forces over a wide range of gape angles, an important advantage for generalist feeders such as caecilians. The relative sizes and leverage mechanics of the two closing systems allow one to exert more force when the other has a poor mechanical advantage. This effect is seen in all three species we examined. In the aquatic T. natans , with its less well-roofed skull, there is a larger contribution of the mm. levatores mandibulae to total bite force than in the terrestrial I . cf. kohtaoensis and S. annulatus .

Download Full-text

A New Geometric Metric in the Shape and Size Space of Curves in R n

Mathematics ◽

10.3390/math8101691 ◽

2020 ◽

Vol 8 (10) ◽

pp. 1691

Author(s):

Irene Epifanio ◽

Vicent Gimeno ◽

Ximo Gual-Arnau ◽

M. Victoria Ibáñez-Gual

Keyword(s):

Nearest Neighbor ◽

Simulated Data ◽

Shape Space ◽

Data Set ◽

Scale Size ◽

The Difference ◽

Active Research ◽

First Time ◽

Shape And Size ◽

Better Than

Shape analysis of curves in Rn is an active research topic in computer vision. While shape itself is important in many applications, there is also a need to study shape in conjunction with other features, such as scale and orientation. The combination of these features, shape, orientation and scale (size), gives different geometrical spaces. In this work, we define a new metric in the shape and size space, S2, which allows us to decompose S2 into a product space consisting of two components: S4×R, where S4 is the shape space. This new metric will be associated with a distance function, which will clearly distinguish the contribution that the difference in shape and the difference in size of the elements considered makes to the distance in S2, unlike the previous proposals. The performance of this metric is checked on a simulated data set, where our proposal performs better than other alternatives and shows its advantages, such as its invariance to changes of scale. Finally, we propose a procedure to detect outlier contours in S2 considering the square-root velocity function (SRVF) representation. For the first time, this problem has been addressed with nearest-neighbor techniques. Our proposal is applied to a novel data set of foot contours. Foot outliers can help shoe designers improve their designs.

Download Full-text

Masticatory system integration in a commensal canid: interrelationships between bones, muscles and bite force in the red fox

Journal of Experimental Biology ◽

10.1242/jeb.224394 ◽

2021 ◽

Vol 224 (5) ◽

Author(s):

Colline Brassard ◽

Marilaine Merlin ◽

Elodie Monchâtre-Leroy ◽

Claude Guintard ◽

Jacques Barrat ◽

...

Keyword(s):

Red Fox ◽

Bite Force ◽

Similar Amount ◽

Canis Lupus Familiaris ◽

Cross Sectional ◽

Domestic Species ◽

Mandible Shape ◽

The Impact ◽

Strong Relationships

ABSTRACT The jaw system in canids is essential for defence and prey acquisition. However, how it varies in wild species in comparison with domestic species remains poorly understood, yet is of interest in terms of understanding the impact of artificial selection. Here, we explored the variability and interrelationships between the upper and lower jaws, muscle architecture and bite force in the red fox (Vulpes vulpes). We performed dissections and used 3D geometric morphometric approaches to quantify jaw shape in 68 foxes. We used a static lever model and bite force estimates were compared with in vivo measurements of 10 silver foxes. Our results show strong relationships exist between cranial and mandible shape, and between cranial or mandible shape on the one hand and muscles or estimated bite force on the other hand, confirming the strong integration of the bony and muscular components of the jaw system. These strong relationships are strongly driven by size. The functional links between shape and estimated bite force are stronger for the mandible, which probably reflects its greater specialisation towards biting. We then compared our results with data previously obtained for dogs (Canis lupus familiaris) to investigate the effect of domestication. Foxes and dogs differ in skull shape and muscle physiological cross-sectional area (PCSA). They show a similar amount of morphological variation in muscle PCSA, but foxes show lower variation in cranial and mandible shape. Interestingly, the patterns of covariation are not stronger in foxes than in dogs, suggesting that domestication did not lead to a disruption of the functional links of the jaw system.

Download Full-text

The relationship between head shape, head musculature and bite force in caecilians (Amphibia: Gymnophiona)

Journal of Experimental Biology ◽

10.1242/jeb.243599 ◽

2021 ◽

Author(s):

Aurélien Lowie ◽

Barbara De Kegel ◽

Mark Wilkinson ◽

John Measey ◽

James C. O'Reilly ◽

...

Keyword(s):

Bite Force ◽

Temporal Region ◽

Head Shape ◽

Skull Shape ◽

Form And Function ◽

Feeding Mechanics ◽

Mandible Shape ◽

And Function ◽

The Relationship

Caecilians are enigmatic limbless amphibians that, with a few exceptions all have an at least partly burrowing lifestyle. Although it has been suggested that caecilian evolution resulted in sturdy and compact skulls as an adaptation to their head-first burrowing habits, no relationship between skull shape and burrowing performance has been demonstrated to date. However, the unique dual jaw-closing mechanism and the osteological variability of their temporal region suggest a potential relationship between skull shape and feeding mechanics. Here, we explored the relationships between skull shape, head musculature, and in vivo bite forces. Although there is a correlation between bite force and external head shape, no relationship between bite force and skull shape could be detected. Whereas our data suggest that muscles are the principal drivers of variation in bite force, the shape of the skull is constrained by factors other than demands for bite force generation. However, a strong covariation between the cranium and mandible exists. Moreover, both cranium and mandible shape covary with jaw muscle architecture. Caecilians show a gradient between species with a long retroarticular process associated with a large and pennate-fibered m. interhyoideus posterior and species with a short process but long and parallel-fibered jaw adductors. Our results demonstrate the complexity of the relationship between form and function of this jaw system. Further studies that focus on factors such as gape distance or jaw velocity will be needed in order to fully understand the evolution of feeding mechanics in caecilians.

Download Full-text

Mandible shape and size in three species of small musk shrews (Crocidura Wagler, 1832) from southern Africa

Mammalia ◽

10.1515/mamm.1996.60.4.753 ◽

1996 ◽

Vol 60 (4) ◽

Cited By ~ 3

Author(s):

P.J. TAYLOR ◽

G. CONTRAFATTO

Keyword(s):

Southern Africa ◽

Mandible Shape ◽

Shape And Size

Download Full-text

Tuning of glyconanomaterial shape and size for selective bacterial cell agglutination

Journal of Materials Chemistry B ◽

10.1039/c5tb02488a ◽

2016 ◽

Vol 4 (11) ◽

pp. 2028-2037 ◽

Cited By ~ 21

Author(s):

J. J. Cid Martín ◽

M. Assali ◽

E. Fernández-García ◽

V. Valdivia ◽

E. M. Sánchez-Fernández ◽

...

Keyword(s):

Escherichia Coli ◽

Carbon Nanotubes ◽

Bacterial Cell ◽

Cell Agglutination ◽

Type 1 Fimbriae ◽

Shape And Size ◽

Better Than

Acting as veritable glue, 1D-coated mannose carbon nanotubes efficiently and selectively regulate the agglutination and proliferation of the enterobacteriaEscherichia colitype 1 fimbriae, much better than the mannose coated 3D-micelles.

Download Full-text

Time and Latitude in South Africa

International Astronomical Union Colloquium ◽

10.1017/s0252921100026816 ◽

1972 ◽

Vol 1 ◽

pp. 27-38

Author(s):

J. Hers

Keyword(s):

South Africa ◽

Cape Town ◽

Astronomical Observations ◽

Royal Observatory ◽

The Republic ◽

Astronomical Determination ◽

Limited Accuracy ◽

Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Download Full-text

Localization of immunolabels by electron microscopy and image averaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075208 ◽

1983 ◽

Vol 41 ◽

pp. 282-283

Author(s):

J. Frank ◽

P.-Y. Sizaret ◽

A. Verschoor ◽

J. Lamy

Keyword(s):

Electron Microscopy ◽

Single Particle ◽

Attachment Site ◽

Uranyl Acetate ◽

Limulus Polyphemus ◽

Resolution Limit ◽

Electron Microscopic ◽

Image Averaging ◽

Top View ◽

Better Than

The accuracy with which the attachment site of immunolabels bound to macromolecules may be localized in electron microscopic images can be considerably improved by using single particle averaging. The example studied in this work showed that the accuracy may be better than the resolution limit imposed by negative staining (∽2nm).The structure used for this demonstration was a halfmolecule of Limulus polyphemus (LP) hemocyanin, consisting of 24 subunits grouped into four hexamers. The top view of this structure was previously studied by image averaging and correspondence analysis. It was found to vary according to the flip or flop position of the molecule, and to the stain imbalance between diagonally opposed hexamers (“rocking effect”). These findings have recently been incorporated into a model of the full 8 × 6 molecule.LP hemocyanin contains eight different polypeptides, and antibodies specific for one, LP II, were used. Uranyl acetate was used as stain. A total of 58 molecule images (29 unlabelled, 29 labelled with antl-LPII Fab) showing the top view were digitized in the microdensitometer with a sampling distance of 50μ corresponding to 6.25nm.

Download Full-text

The Alteration of the Pore Spaces in Sandstones

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071491 ◽

1973 ◽

Vol 31 ◽

pp. 210-211

Author(s):

R. E. Ferrell ◽

G. G. Paulson

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

The Other ◽

Coarse Grained ◽

Depositional Fabric ◽

Soluble Components ◽

Scanning Electron ◽

Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

Download Full-text