Sex Determination in Japanese Quails (Coturnix japonica) Using Geometric Morphometrics of the Skull

Shape variations of pelvis in different classes of dogs using geometric morphometry

The ossa coxae are the bones that connect the hindlimbs to the axial skeleton. The right and left os coxae join at the median plane to form the pelvis. In this study, variations in pelvis shape and the asymmetric structure of the pelvis were investigated across different classes of dogs. To achieve this, computed tomography images of the pelvis were obtained from 35 dogs, and 3D modelling of the pelvis was created. Subsequently, 45 landmarks were identified on these models. As a result of the Principal Component Analysis, the shape variation was observed in the pelvic canal and crista iliaca. Directional asymmetry between Principal Component 1 and Principal Component 2 accounted for 33.84% of the total variation, while fluctuating asymmetry contributed 23.66%. Canonical variate analysis revealed that canonical variate (CV) 1 explained 56.56% of the total variation between groups, with CV 2 explained 28.98%. Male dogs exhibited greater pelvic variation than females. Procrustes ANOVA indicated that the greatest proportion of shape variation corresponds to the effect of differences among individuals. While directional asymmetry was statistically significant, fluctuating asymmetry was not. Male dogs displayed more pronounced pelvic shape asymmetry, typically towards the right. Gundogs had a narrower pelvic canal and a wide crista iliaca, whereas terriers had a wider pelvic canal and smaller crista iliaca in shape. Geometric morphometry enables statistical analysis and the derivation of average shapes from samples, making it a vital tool in veterinary anatomy. This study provides insights into pelvic geometric morphometry across different classes of dogs.

Shape variation in cranium, mandible and teeth in selected mouse strains

There are different strains of laboratory mouse used in many different fields. These strains differ anatomically. In order to determine these anatomical differences, shape analysis was conducted according to species. CD-1, C57bl/6 and Balb-c strains were preferred to study these differences. Forty-eight adult mouse strains belonging to these strains were utilized. The bones were photographed and geometric morphometry was applied to these photographs. Principal Component Analysis was applied to determine shape variations. In Principal component 1 for cranium, CD-1 and C57bl/6 strain groups showed different shape variations, while Balb-c strain group showed similar shape variations to the other strain groups. Principal Component 1 for the mandible separated the CD-1 and C57bl/6 strain groups in terms of shape variation. Principal Component 2 explained most of the variation between the C57bl/6 and CD-1 lineage groups. In PC1 for molars, the CD-1 group showed a different shape variation from the other groups. Mahalanobis distances and Procrustes distances were measured using Canonical variance analysis to explain the differences between the lineage groups. These measurements were statistically significant. For cranium, in canonical variate 1, CD-1 group of mouse and Balb-c group of mouse were separated from each other. In canonical variate 2, C57bl/6 group of mouse were separated from the other groups. For mandible, Balb-c group of mouse in canonical variate 1 and CD-1 group of mouse in canonical variate 2 were separated from the other groups. For molars, CD-1 group of mouse in canonical variate 1 and Balb-c group of mouse in canonical variate 2 were separated from the other groups. It was thought that these anatomical differences could be caused by genotypic factors as well as dietary differences and many different habits that would affect the way their muscles work.

Size and shape of the neurocranium of laying chicken breeds

The neurocranium in birds provides valuable insights into their morphological diversity, including adaptations related to brain size, facial shaping, and environmental factors. This study analyzes the neurocranial shape characteristics and size of chickens with similar genetic backgrounds. By examining the neurocranial shape variation in chickens of the same age and sex, the study aims to understand the factors contributing to morphological diversity within this specific group. 3D geometric morphometrics was used to analyze 235 neurocrania from four chicken breeds. The analysis revealed significant differences in centroid size among the chicken breeds. The largest neurocranium centroid size was found in Sasso chickens., which were statistically separated from Atak-S. Additionally, centroid size effectively differentiates between Lohmann Brown and Lohmann Sandy chicken breeds. The most significant shape variation concerned the width of the rostral part of the frontal bone. However, according to the PC1 value, the shape variation was observed within rather than between groups. Lohmann Sandy chickens exhibited higher variability in neurocranial shape, suggesting greater shape diversity within this breed than others. As for shape analysis, the breeds showed closer similarity to each other. Lohmann Sandy chickens are characterized by positive PC1 value, with the rostral end of the frontal region inclined more ventrally, and a more extensive basioccipital region. Sasso chickens have a more dome-shaped middle part of the frontal region than other breeds. The study also identified the most significant shape variation among the study samples, observed at the rostral part of the frontal bone. These findings contribute to understanding the genetic and environmental influences shaping neurocranial morphology in chickens. Similar studies in different bird species and subspecies offer valuable insights into avian biology and adaptation.

Skull asymmetry in various sheep breeds: Directional asymmetry and fluctuating asymmetry

Sheep (Ovis aries) play an important role in the economy of Turkey and the Balkan Peninsula due to their use in farming. As a domesticated species, sheep's morphometric and morphological diversity is likely determined by selective breeding practices rather than geographic distribution. This study aimed to analyse four different sheep breed skulls and reveal skull asymmetry using geometric morphometric methods. For this purpose, 2D images of 52 sheep skulls from different breeds were analysed from the dorsal view of the skull, using 28 landmarks. In the comparison of sheep skulls from the dorsal view, the first principal components for directional asymmetry (DA) and fluctuating asymmetry (FA) were 32.98% and 39.62% of the total variation, respectively. Sharri and Ivesi (Awassi) sheep breeds had the broadest distribution of skull shapes among the breeds, while Lara e Polisit was the most conservative breed. DA was used as a measure of biomechanical constraints, and FA was used as an indicator of environmental stress. Consistent with DA, both differences in centroid size and shape between breeds were statistically significant. No differences between males and females related to asymmetry were revealed. Ivesi sheep revealed the highest fluctuating asymmetry. Geometric morphometric methods proved to be a useful tool for distinguishing differences in the shape of the skull of different sheep breeds and also can be useful for taxonomic purposes.

Determination of skull variation in Akkaraman and Kangal Akkaraman sheep by geometric morphometric method

Sheep breeding has an important place in the world and in Turkey, as sheep are farm animals that provide most of their nutritional needs from pasture, have good adaptability and are low in cost. Akkaraman sheep and the Kangal Akkaraman sheep, which was considered its sub-variety until 2012, constitute half of the sheep population in Turkey. In this study, morphometric diversity between the skulls of Akkaraman and Kangal Akkaraman breed sheep was examined by geometric morphometric method. 2D images obtained from 3D models of 24 male sheep skulls from two different provinces were analyzed using 10 landmarks from dorsal and lateral views. The results from the dorsal view, the first three principal components (PC1, PC2 and PC3) accounted for a total of 64.13% of the morphological variation and the largest changes in are associated with external occipital protuberance, midline nasofrontal suture and rostral edge of the incisive fissure. From the lateral view, three first principal components explained the morphological variation 27.56%, 22.32% and 10.65% respectively. In the comparison of the skull morphology of Akkaraman and Kangal Akkaraman sheep from dorsal and lateral views, no allometric components were identified, as most of the described shape variations were not size-dependent. As a result of these analyses, more detailed information was obtained about the shape differences of the skull. Geometric morphometric analysis is successful in detecting differences in skull shape of different sheep breeds and can be successfully used for classification.

Evaluation of sex differences in pelvis and femur x-ray images in British shorthair cats by geometric morphometric method

The study covers British Shorthair cats, which is a popular domestic cat breed in our country and defined as 'brachycephalic' in terms of skull structure. Article focuses on the pelvis and femur region of cats which gynaecological and orthopaedic diseases of this cat breed, which are frequently encountered in clinical practice, is found to be important. It is aimed to reveal the shape differences between male and female individuals using geometric morphometric method. X-ray images were used to examine the pelvis and femurs of cats via geometric method. Radiological images were obtained from a total of 40 British Shorthair cats (20 females and 20 males) in two positions, ventro-dorsal (VD) and latero-lateral (LL), and shape differences between the sexes were examined. As result, it is seen that the measurement points taken from the males are more outward and have sharper angles than the females. Study also shows pelvis is a better choice than femur when it comes to sex discrimination. Although traditional morphometric methods are more useful in clinical practice, it is thought that is important to support or re-evaluate the data with the geometric morphometric method in academic field for a further approach.

Radiological examination of the skull of Siirt-coloured mohair goat, Romanov and Hamdani sheep

The skull is a vitally important complex structure formed by the combination of many bones. Craniometric studies are performed with various imaging methods to determine morphometric characteristics in animals. One of these methods is radiography. In our study, skulls of 14 Hamdani sheep, 20 Siirt-coloured mohair goats and 20 Romanov sheep breeds were used. Skull sections were taken with a computed tomography device and saved in DICOM format. Nine separate measurements and six index calculations were made from the images. In the study, firstly, the gender difference was ignored and the similarities and differences between the species were recorded. In addition, gender differences were determined statistically, without making any distinction between species. Correlation analysis was performed to compare measurement parameters between animal species. As a result of the study, the highest skull length (SL) and cranial length (CL) values were determined in the Siirt-coloured mohair goat. It was determined that the difference between Romanov sheep and Siirt-coloured mohair goat in CL parameter was not statistically significant (p > 0.05). In addition, a statistically significant difference was observed between the Romanov sheep breed and the Hamdani sheep breed (p < 0.01). The external length of the cranium (ELC) measurement parameter was found to have a statistically significant difference in three animals (p < 0.01). According to the results of the correlation analysis, the highest correlation value was determined between cranial width (CW) and CL parameters (r = 0.920). When the species difference was ignored, and the statistical difference of the internal height of the cranium (IHC) parameter was found to be significant between female and male animals (p < 0.05). In addition, it was determined that SL, CW and internal cranium index (ICI) parameters had a significant difference depending on sex (p < 0.01). It is foreseen that the obtained data can be used in sciences such as zoo archaeology, anatomy, surgery and forensic medicine.

Shape analysis of fossa masseterica and processus coronoideus in domestic cats (Felis catus) and domestic dogs (Canis familiaris)

Fossa masseterica, to which the musculus masseter is attached, is the pit on the lateral surface of the ramus mandibulae. Processus coronoideus is a protrusion on the upper part of fossa masseterica. Carnivores have a more developed fossa masseterica and a wider processus coronoideus than other species, due to their well-developed jaw muscles. However, there is limited information about the differences of these two structures among carnivorous species. In this study, it was investigated whether fossa masseterica and processus coronoideus differ in shape in domestic cats and domestic dogs. For this purpose, 22 dogs and 20 cats were examined by 3D geometric morphometry. Eighty-one landmarks were used on the fossa masseterica and processus coronoideus. The difference in centroid sizes and shape for cats and dogs was statistically significant (p < 0.0001). PC1 explained 26.47% of the total variance. It was seen that cats and dogs were completely separated according to PC1 results. In cats with a high PC1 value, the processus coronoideus was narrower than in dogs. Also, feline processus coronoideus was more curved than domestic canine processus coronoideus. In addition, the caudal inclination of processus coronoideus was deeper in dogs than in cats. Dogs had a negative PC1 value except for one sample (German Shepherd). The sample with the lowest PC1 value was the French Bulldog (female, 7 years, and 13 kg). Discriminant analysis results showed that the domestic cats and domestic dogs used in the study were completely separated from each other, and this difference was statistically significant. The results of this study showed that dogs with stronger jaw muscles had a deeper fossa masseterica and a wider processus coronoideus than cats.

Geometric and Morphometric Analysis of the Auditory Ossicles in the Red Fox (Vulpes vulpes)

The use of carnivores as experimental models in auditory biology has led to a significant improvement regarding our understanding of the structure and function of the ear. Considering that data regarding the anatomy of the middle ear in the red fox are rare, this study aimed to describe the morphological and morphometrical features of the auditory ossicles in the red fox, as well as to provide their shape characteristics by geometric analysis. Nine adult red foxes were used in the study. The malleus, incus and stapes were extracted from the middle ear, prepared, photographed and measured using the software. For the geometric analysis, 19 landmarks were used. Following Principal Component Analysis (PCA), PC1 was found to explain approximately half of all variance (incus: 49.97%; malleus: 49.93%; stapes: 58.49%). The study demonstrated the similar anatomical organization of the auditory ossicles in line with important morphometric and basic geometric data, which can contribute to this field and add a useful perspective to the literature.

Shape differences of the Carina sterni in birds of various locomotion types

The anatomy of the sternum in birds varies according to their habitats and type of locomotion. In particular, the carina sterni manifest different shape variations. In this study, the shape of the carina sterni was investigated by means of geometric morphometrics. Birds of different types of locomotion were used in the study: flying, swimming, and terrestrial. Ducks and chickens show a wider variety of shapes. Pigeons are the species with the least differences. The margo cranialis carinae in a turkey is the flattest compared to other species. In chickens, the apex carinae is more caudally than the base of the carina sterni. The margo cranialis of the carina sterni in ducks is concave. The differences in centroid size and shape differences between species collectively are statistically significant (p < 0.0001). The most distinct shape contrast is between the duck and turkey (p: 0.0003). Form differences between the ducks and geese as well as between the chicken and turkey are statistically insignificant. There is less variation in the shape of the carina sterni among avian species representing the same type of locomotion. Although there are many comparative morphological and morphometric studies of birds, shape analysis studies revealing the interspecific differences and similarities of the sternum are very limited. Morphology of the carina sterni can be useful in taxonomic investigations.

Radiographic analysis of skull in Van Cats, British Shorthairs and Scottish Folds

The most significant bone used in taxonomic research is the skull. This study attempted to identify differences between the three cat species by measuring the skulls of each using computed tomography sections. The study used a total of 32 cat skulls, including 16 Van Cats, eight British Shorthairs and eight Scottish Folds. Van Cat had the highest values for cranial and skull length, whereas British Shorthair had the lowest values. The difference between the British Shorthair and Scottish Fold skull length and cranial length measures was not statistically significant. However, the Van Cat skull length result was statistically different from other species (p < 0.05). Scottish Fold had the broadest head (cranial width: 41.02 ± 0.79 mm). These results demonstrated that the scull of the Van Cat was longer but thinner than that of other species. In comparison to other species, the form of the Scottish Fold skull was more rounded. Internal height of cranium measurements for Van Cat and British Shorthair were statistically significant. In Van Cats, this measurement was 27.81 ± 1.58 mm, while in British Shorthairs, it was 30.23 ± 1.89 mm. Measurements of the foremen magnum were not statistically significant for any species. Van Cat's measures for the foramen magnum were the highest (Foramen magnum height: 11.59 ± 0.93 mm; Foramen magnum width: 14.18 ± 0.70 mm). Scottish Fold had the highest cranial index (Cranial index: 55.50 ± 4.02). Van Cat had the lowest value for this (Cranial index: 50.19 ± 2.16). Van Cat's cranial index value differed statistically from that of other species (p < 0.05). Between species, the foramen magnum index was not significant. None of the index values were statistically significant for Scottish Fold and British Shorthair. Foramen magnum width had the highest age-to-measurement value correlation (r = 0.310), although it was statistically insignificant. Skull length had the highest weight-to-measurement value correlations (R = 0.809), and it proved to be statistically significant. Skull length was the measuring value that distinguished male and female the most clearly (p = 0.000).

Examination of Shape Variation of the Skull in British Shorthair, Scottish Fold, and Van Cats

A variety of skull shapes are frequently used for discrimination between animal species, breeds, and sexes. In this study, skulls of three different breeds of cats were examined by the geometric morphometric method, with the aim of revealing skull shape differences. For this purpose, 27 cats (6 British Shorthair, 7 Scottish Fold, and 14 Van cats) were used. The skulls of cats were modeled by computed tomography. Geometric morphometrics was applied using dorsal (8 landmarks, 63 semilandmarks) and lateral (8 landmarks, 63 semilandmarks) skull projections on these models. Centroid size differences between the breeds were statistically insignificant. However, the differences in shape were statistically significant for both the dorsal view and lateral view. Shape variation was less in the British Shorthair than in other breeds. Shape differences generally occurred around the orbit. In the skull of Scottish Folds, the orbit was situated more caudally than in other breeds. The British Shorthair had the largest orbital ring. In dorsal view, the Scottish Fold had the largest orbital diameter. The orbital ring of Van cats was smallest in both dorsal and lateral views. In the canonical variate analysis, it was seen that the breeds were separated from each other. The shape difference in the skull between different cat breeds could be revealed by geometric morphometrics. The results of this study provide useful information for taxonomy.

Morphometric analysis for the sex determination of the skull of the Deltari Ilir dog (Canis lupus familiaris) of Kosovo

This study aimed to explain the sex determination of the autochthonous dog Deltari Ilir with both morphometric and geometric analysis methods. For this purpose, 24 Deltari Ilir dog skulls (12 females and 12 males) were used in the study. The difference between males and females at 6 values was statistically significant. The most statistically significant difference was seen in the measurement of the greatest breadth of the occipital condyles (p < 0.000). This measurement was higher in male skulls. The next most significant difference was seen in the greatest inner height of the orbit measurement (p < 0.002). This measurement was also higher than for females. In general, the skull length measurements of male dogs were higher than that of females. Male dog skulls had greater skull length and skull height. The lateral view was used for geometric analysis and 14 landmarks were determined. As a result of principal component analysis, 22 PC values were obtained. PC1 accounted for 23.73% of the total variance. As a result of canonical variants analysis, it was observed that males and females were completely separated from each other. The caudal part of the males was wider than the females in geometric analysis. As a result of the study, sex-determining characteristics were revealed for the Deltari Ilir dog. It was seen that gender analysis could be done with both morphometric and geometric analysis methods. In addition, it was seen that morphometric results and geometric analysis results supported each other. Moreover, the results of the study will be useful in the function of comparative anatomy, in veterinary clinical practice, in zooarchaeology but why not also in the veterinary forensic investigation.