RESUMEN
Despite their distinct embryonic origins, the skull and brain are highly integrated. Understanding the covariation between the skull and brain can shed light on anatomical, cognitive, and behavioral traits in extant and extinct species. Domestic dogs offer a unique opportunity to investigate skull-brain covariation due to their diverse skull morphologies and neural anatomy. To assess this question, we examined T2-weighted MRI studies of 62 dogs from 33 breeds, plus an additional 17 dogs of mixed or unknown breeds. Scans were opportunistically collected from a veterinary teaching hospital of dogs that were referred for neurological examination but did not have grossly observable structural brain abnormalities. As the neurocrania of dogs become broader and shorter, there is a significant decrease in the gray matter volume of the right olfactory bulb, frontal cortex, marginal gyrus, and cerebellum. On the other hand, as the neurocrania of dogs become narrower and longer, there is a significant decrease in the gray matter volume of the olfactory bulb, frontal cortex, temporal cortex, amygdala, hypothalamus, hippocampus, periaqueductal gray, cerebellum, and brainstem. Selective breeding for specific skull shapes may impact canine brain anatomy and function.
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Encéfalo , Imagen por Resonancia Magnética , Cráneo , Animales , Perros/anatomía & histología , Encéfalo/anatomía & histología , Cráneo/anatomía & histología , Cráneo/diagnóstico por imagen , Masculino , Femenino , Sustancia Gris/anatomía & histología , Sustancia Gris/diagnóstico por imagenRESUMEN
The plains vizcacha, Lagostomus maximus, is the only living species in the genus, being notably larger than fossil congeneric species, such as Lagostomus incisus, from the Pliocene of Argentina and Uruguay. Here, we compare the skull growth allometric pattern and sexual dimorphism of L. maximus and L. incisus, relating shape and size changes with skull function. We also test whether the ontogenetic trajectories and allometric trends between both sexes of L. maximus follow the same pattern. A common allometric pattern between both species was the elongation of the skull, a product of the lengthening of rostrum, and chondrogenesis on the spheno-occipitalis synchondrosis and coronalis suture. We also detected a low proportion of skull suture fusion. In some variables, older male specimens did not represent a simple linear extension of female trajectory, and all dimorphic traits were related to the development of the masticatory muscles. Sexual dimorphism previously attributed to L. incisus would indicate that this phenomenon was present in the genus since the early Pliocene and suggests social behaviors such as polygyny and male-male competition. Ontogenetic changes in L. incisus were similar to L. maximus, showing a conservative condition of the genus. Only two changes were different in the ontogeny of both species, which appeared earlier in L. incisus compared to L. maximus: the development of the frontal process of the nasals in a square shape, and the straight shape of the occipital bone in lateral view. Juveniles of L. maximus were close to adult L. incisus in the morphospace, suggesting a peramorphic process. The sequence of suture and synchondroses fusion showed minor differences in temporozygomatica and frontonasalis sutures, indicating major mechanical stress in L. maximus related to size. We suggest a generalized growth path in Chinchillidae, but further analyses are necessary at an evolutionary level, including Lagidium and Chinchilla.
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Fósiles , Caracteres Sexuales , Cráneo , Animales , Cráneo/anatomía & histología , Cráneo/crecimiento & desarrollo , Masculino , Femenino , Fósiles/anatomía & histología , Roedores/anatomía & histología , Roedores/crecimiento & desarrollo , Evolución Biológica , Suturas Craneales/anatomía & histología , Suturas Craneales/crecimiento & desarrolloRESUMEN
Despite the significance of anatomical variability in various specialties, there is currently limited research dedicated to this topic. Most studies focus on the brain, with only a small number examining the human skull, primarily in relation to anatomical variability in childhood. AIM: Therefore, the aim of our work is to determine the individual anatomical variability of the lateral dimensions of the facial section of the adult human skull. MATERIALS AND METHODS: The study included 115 skulls of mature individuals, comprising 35 dry bone specimens from the anatomy museum collection and 80 results from human head CT scans without bone tissue pathologies. To detail the craniometric characteristics of the lateral surface of the facial section of the skull, polygons (polygons) were constructed with dividing of the facial section of the skull is into the orbital-frontal, nasal, and maxillary. The facial profilegram of the skull was formed as a set of predetermined dimensions between facial profile points, presenting a continuous line passing through points gl-n-rhi-ns-pr-id-pg, reflecting the shape, dimensions, and position of the cranial profile of mature adults regardless of sex or cranial type. RESULTS: It was established that the longitudinal anteroposterior dimensions of the facial skull exhibit a certain range of variability in mature individuals depending on gender. For instance, the distance between the points gl-po (glabella-porion) reaches its maximum values in individuals with a brachycranial skull shape, ranging from 107 mm to 130 mm in men and from 104 mm to 128 mm in women. In individuals with a mesocranial skull shape, this parameter gradually decreases to 109-126 mm in men and 107-124 mm in women. A similar decrease is observed in those with a dolichocranial skull shape, where the range is 109-121 mm in men and 109-120 mm in women. The distance between n-po (nasion-porion) in brachycranial and mesocranial individuals remains within 96-123 mm and 102-123 mm, regardless of gender, indicating that this parameter is relatively stable. However, in dolichocranial individuals, this distance decreases to 104-115 mm. CONCLUSIONS: Individual anatomical variability of the anteroposterior lateral dimensions of the facial skeleton in mature individuals has been determined. A more in-depth analysis of the existing range of individual variability in the profile configuration of the facial skull was conducted using sagittal polygons. It was found that the polygons gl-po-n, n-po-rhi, and rhi-po-ns relate to the structure of the bony profile of the orbital-temporal and nasal regions of the facial skull, reflecting the upper, combined orbital-nasal section of the head.
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Cefalometría , Cráneo , Humanos , Femenino , Masculino , Adulto , Cráneo/anatomía & histología , Cráneo/diagnóstico por imagen , Cefalometría/métodos , Tomografía Computarizada por Rayos X , Persona de Mediana Edad , Variación Anatómica , Huesos Faciales/anatomía & histología , Huesos Faciales/diagnóstico por imagenRESUMEN
While brain size in primates and their relatives within Euarchontoglires is well-studied, less research has examined brain shape, or the allometric trajectories that underlie the relationship between size and shape. Defining these patterns is key to understanding evolutionary trends. 3D geometric morphometric analyses of endocranial shape were performed on 140 species of extant euarchontoglirans using digital cranial endocasts. Principal component analyses on Procrustes shape variables show a clear phylogenetic pattern in endocranial shape, supported by an ANOVA which identified significant differences in shape among several groups (e.g., Platyrrhini, Strepsirrhini, Scandentia, Rodentia, and Lagomorpha). ANOVAs of shape and size also indicate that allometry has a small but significant impact on endocranial shape across Euarchontoglires, with homogeneity of slopes tests finding significant differences in the scaling relationship between shape and size among these same groups. While most of these clades possess a distinct endocranial morphotype, the highly derived platyrrhines display the strongest relationship between size and shape. Rodents show the most diversity in endocranial shape, potentially attributed to their comparatively weak relationship between shape and size. These results suggest fundamental differences in how shape and size covary among Euarchontoglires, which may have facilitated the adaptive radiations that characterize members of this group.
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Evolución Biológica , Filogenia , Cráneo , Animales , Cráneo/anatomía & histología , Fósiles/anatomía & histología , Análisis de Componente Principal , Encéfalo/anatomía & histología , Primates/anatomía & histologíaRESUMEN
Biological variation in the mammalian skull is the product of a series of factors including changes in gene expression, developmental timing, and environmental pressures. When considering the diversity of extant mammalian crania, it is important to understand these mechanisms that contribute to cranial growth and in turn, how differences in cranial morphology have been attained. Various researchers, including Dr. Sue Herring, have proposed a variety of mechanisms to explain the process of cranial growth. This work has set the foundation on which modern analysis of craniofacial morphology happens today. This study focused on the analysis of modularity in three mammalian taxa, all of which exhibit facial reduction. Specifically, we examined facial reduction as a morphological phenomenon through the use of two-module and six-module modularity hypotheses. We recorded three-dimensional coordinate data for 55 cranial landmarks that allowed us to analyze differences in cranial shape in these three taxa (primates n = 88, bats n = 64, dogs n = 81). When assessing modularity within the two-module modularity hypothesis specifically, dogs exhibited the lowest levels of modularity, while bats and primates both showed a slightly more modular covariance structure. We further assessed modularity in the same sample using the Goswami six-module model, where again dogs exhibited a low degree of modularity, with bats and primates being more moderate. We then broke the sample into subsets by analyzing each morphotype separately. We hypothesized that the modularity would be more pronounced in the brachycephalic morphotype. Surprisingly, we found that in brachycephalic dogs, normocephalic dogs, brachycephalic primates, and normocephalic primates, there was a moderate degree of modularity. Brachycephalic bats had a low degree of modularity, while normocephalic bats were the most modular group observed in this study. Based on these results, it is evident that facial reduction is a complex and multifaceted phenomenon with unique morphological changes observed in each of the three taxa studied.
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Quirópteros , Cara , Primates , Cráneo , Animales , Quirópteros/anatomía & histología , Cráneo/anatomía & histología , Perros/anatomía & histología , Primates/anatomía & histología , Cara/anatomía & histología , Evolución BiológicaRESUMEN
The study of evolutionary rates and patterns is the key to understand how natural selection shaped the current and past diversity of phenotypes. Phylogenetic comparative methods offer an array of solutions to undertake this challenging task, and help understanding phenotypic variation in full in most circumstances. However, complex, three-dimensional structures such as the skull and the brain serve disparate goals, and different portions of these phenotypes often fulfil different functions, making it hard to understand which parts truly were recruited by natural selection. In the recent past, we developed tools apt to chart evolutionary rate and patterns directly on three-dimensional shapes, according to their magnitude and direction. Here, we present further developments of these tools, which now allow to restitute the mapping of rates and patterns with full biological realism. The tools are condensed in a new R software package.
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Evolución Biológica , Fenotipo , Filogenia , Programas Informáticos , Animales , Imagenología Tridimensional , Cráneo/anatomía & histología , Humanos , Selección GenéticaRESUMEN
PURPOSE: The aim of this study was to find an alternative method to meet traditional human anatomy teaching and clinical needs in order to solve the problem of cranial specimen attrition and specimen resource shortage due to long-term use. METHODS: We performed a computed tomography (CT) scan of a well-preserved male cranial specimen and used Mimics 19.0 software for 3D reconstruction and cranial block separation. Subsequently, we compared the recognition ability of the processed cranial digital model with that of the 3D body digital model and used 3D printing to create the cranial model and compare it with the physical specimen. RESULTS: Twenty-two cranial bone block models were obtained, excluding the hyoid bone. Their 3D reconstructed digital models had better bony landmark recognition than the 3D body human digital models, and the differences between the 3D printed models and the physical specimens were minimal. In addition, only one stereolithography (STL) file was required to produce the cranial models, which facilitates repetitive printing at any time. CONCLUSION: By isolating cranial bone blocks through 3D reconstruction techniques and preparing high-quality cranial models in combination with 3D printing techniques, this study solves the problem of shortage of cranial teaching specimens for the sustainable development of clinical and medical schools.
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Imagenología Tridimensional , Modelos Anatómicos , Impresión Tridimensional , Cráneo , Tomografía Computarizada por Rayos X , Humanos , Cráneo/anatomía & histología , Cráneo/diagnóstico por imagen , Masculino , Estereolitografía , Cadáver , Programas InformáticosRESUMEN
The mechanosensory lateral line (LL) system of salmonid fishes has been the focus of comparative morphological studies and behavioral and physiological analyses of flow sensing capabilities, but its morphology and development have not been studied in detail in any one species. Here, we describe the post-embryonic development of the cranial LL system in Brook Trout, Salvelinus fontinalis, using vital fluorescent staining (4-Di-2-ASP), scanning electron microscopy, µCT, and clearing and staining to visualize neuromasts and the process of cranial LL canal morphogenesis. We examined the relationship between the timing of LL development, the prolonged life history of salmonids, and potential ecological implications. The LL system is composed of seven canals containing canal neuromasts (CNs) and four lines of superficial neuromasts (SNs) on the skin. CNs and SNs increase in number and size during the alevin (larval) stage. CN number stabilizes as canal morphogenesis commences, but SN number increases well into the parr (juvenile) stage. CNs become larger and more elongated than SNs, but the relative area occupied by sensory hair cells decreases during ontogeny in both types of neuromasts. Neuromast-centered canal morphogenesis starts in alevins (yolk sac larvae), as they swim up into the water column from their gravel nests (~4 months post-fertilization), after which yolk sac absorption is completed and exogenous feeding begins. Canal morphogenesis proceeds asynchronously within and among canal series and is not complete until ~8 months post-fertilization (the parr stage). Three characters in the LL system and associated dermal bones were used to identify their homologs in other actinopterygians and to consider the evolution of LL canal reduction, thus demonstrating the value of salmonids for the study of LL evolution. The prolonged life history of Brook Trout and the onset of canal morphogenesis at swim-up are predicted to have implications for neuromast function at these critical behavioral and ecological transitions.
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Evolución Biológica , Sistema de la Línea Lateral , Trucha , Animales , Sistema de la Línea Lateral/embriología , Sistema de la Línea Lateral/ultraestructura , Sistema de la Línea Lateral/crecimiento & desarrollo , Trucha/anatomía & histología , Trucha/crecimiento & desarrollo , Trucha/embriología , Larva/crecimiento & desarrollo , Cráneo/anatomía & histología , Cráneo/crecimiento & desarrollo , Cráneo/embriología , MorfogénesisRESUMEN
The skull is a complex, vital structure made up of many bones. It has been observed that studies on skulls help to determine species and sex. In recent years, craniometric studies have been frequently used to determine morphometric features in animals. In our study, 150 skulls were studied, 50 from the second trimester (25 males and 25 females), 50 from the third trimester (25 males and 25 females), and 50 from the third and fourth week after birth (25 males and 25 females). The skulls were sectioned by computerised tomography and stored in DICOM format. From the images, nine different measurements and five index calculations were made. The similarities and differences between species were determined by ignoring sex differences. Correlation analyses were performed to compare measurement parameters between animal species. In addition, the results of statistical analyses between sexes were evaluated without species distinction. SL, CW and ICI parameters were highly statistically significant between measurements in the second trimester, third trimester and postnatal group (p < 0.01). In the third trimester, the EHC measurement parameter was found to be highly significant between males and female (p < 0.01). In Table 5, the CL parameter was positively correlated with CW, IHC, EHC, ILC, ELC, FMW and FMH. There are very few studies on foetal development. It is predicted that the data obtained can be used in zoo-archaeology, anatomy, surgery and forensic medicine. In addition, radiographic determination of craniometric features will help in the treatment and prognosis of diseases.
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Cráneo , Animales , Femenino , Cráneo/diagnóstico por imagen , Cráneo/anatomía & histología , Masculino , Embarazo , Ovinos/anatomía & histología , Tomografía Computarizada por Rayos X/veterinaria , Cefalometría/métodosRESUMEN
Modern birds possess highly encephalized brains that evolved from non-avian dinosaurs. Evolutionary shifts in developmental timing, namely juvenilization of adult phenotypes, have been proposed as a driver of head evolution along the dinosaur-bird transition, including brain morphology. Testing this hypothesis requires a sufficient developmental sampling of brain morphology in non-avian dinosaurs. In this study, we harness brain endocasts of a postnatal growth series of the ornithischian dinosaur Psittacosaurus and several other immature and mature non-avian dinosaurs to investigate how evolutionary changes to brain development are implicated in the origin of the avian brain. Using three-dimensional characterization of neuroanatomical shape across archosaurian reptiles, we demonstrate that (i) the brain of non-avian dinosaurs underwent a distinct developmental trajectory compared to alligators and crown birds; (ii) ornithischian and non-avialan theropod dinosaurs shared a similar developmental trajectory, suggesting that their derived trajectory evolved in their common ancestor; and (iii) the evolutionary shift in developmental trajectories is partly consistent with paedomorphosis underlying overall brain shape evolution along the dinosaur-bird transition; however, the heterochronic signal is not uniform across time and neuroanatomical region suggesting a highly mosaic acquisition of the avian brain form.
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Evolución Biológica , Aves , Encéfalo , Dinosaurios , Fósiles , Cráneo , Animales , Dinosaurios/anatomía & histología , Dinosaurios/crecimiento & desarrollo , Encéfalo/anatomía & histología , Encéfalo/crecimiento & desarrollo , Aves/anatomía & histología , Aves/crecimiento & desarrollo , Cráneo/anatomía & histología , Cráneo/crecimiento & desarrollo , Filogenia , Caimanes y Cocodrilos/anatomía & histología , Caimanes y Cocodrilos/crecimiento & desarrolloRESUMEN
Hemiphractids have a singular mode of reproduction that involves maternal care. The Andean-endemic Gastrotheca marsupiata species group includes direct-developing and tadpole-bearing species, the latter trait being unique among Gastrotheca. Larval morphology has proven to be a valuable source of evidence to understand the taxonomy and evolution of frogs but remains understudied in Hemiphractids. Herein, we redescribe the larval cranium of G. espeletia, G. gracilis, G. marsupiata, G. peruana, G. pseustes, and G. riobambae, and describe those of G. aureomaculata, G. chrysosticta, G. litonedis, G. monticola and G. psychrophila. Additionally, based on the data gathered, we explore their phylogenetic significance, expanding the knowledge regarding Gastrotheca larval internal morphology. We suggest that the presence of the posterolateral process of crista parotica, the concave palatoquadrate, the quadratoorbital commissure, and the proximal commissures II and III are putative synapomorphies for Gastrotheca. Furthermore, we suggest the long pseudopterygoid process as a putative synapomorphy for Hemiphractyidae.
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Anuros , Evolución Biológica , Larva , Cráneo , Animales , Larva/anatomía & histología , Anuros/anatomía & histología , Cráneo/anatomía & histología , FilogeniaRESUMEN
Constraint is a fundamental concept in evolutionary theory. Morphology and ecology both are limited by functional, historical and developmental factors to a subset of the theoretical range species could occupy. Cat-like carnivorans (Feliformia) offer a unique opportunity to investigate phenotypic constraint, as several feliform clades are purported to be limited to generalized ecomorphological roles, while others possess extremely specialized durophagous (bone-crushing) and sabretooth morphology. We investigated the evolutionary history of feliforms by considering their phylogeny, morphological disparity and rates of evolution. We recover results that show a mosaic pattern exists in the degree of morphological disparity per anatomical region per clade and ecology. Non-hypercarnivores, such as viverrids (civets and genets), Malagasy euplerids and lophocyonids (extinct hypocarnivores), have the greatest dental disparity, while hypercarnivores (felids, nimravids, many hyaenids) have the lowest dental disparity but highest cranial and mandibular disparity (excluding dentition). However, high disparity is not necessarily associated with high rates of evolution, but instead with ecological radiations. We reveal that relationships between specialization and disparity are not as simple as past research has concluded. Instead, morphological disparity results from an anatomical mosaic of evolution, where different ecologies correlate with and likely channel unique patterns/combinations of disparity per anatomical partition.
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Evolución Biológica , Filogenia , Animales , Cráneo/anatomía & histología , Fósiles/anatomía & histologíaRESUMEN
Fossil identification practices have a profound effect on our interpretation of the past because these identifications form the basis for downstream analyses. Therefore, well-supported fossil identifications are necessary for examining the impact of past environmental changes on populations and communities. Here we apply an apomorphic identification framework in a case study identifying fossil lizard remains from Hall's Cave, a late Quaternary fossil site located in Central Texas, USA. We present images and descriptions of a broad comparative sample of North American lizard cranial elements and compile new and previously reported apomorphic characters for identifying fossil lizards. Our fossil identifications from Hall's Cave resulted in a minimum of 11 lizard taxa, including five lizard taxa previously unknown from the site. Most of the identified fossil lizard taxa inhabit the area around Hall's Cave today, but we reinforce the presence of an extirpated species complex of horned lizard. A main goal of this work is to establish a procedure for making well-supported fossil lizard identifications across North America. The data from this study will assist researchers endeavoring to identify fossil lizards, increasing the potential for novel discoveries related to North American lizards and facilitating more holistic views of ancient faunal assemblages.
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Fósiles , Lagartos , Cráneo , Animales , Fósiles/anatomía & histología , Lagartos/anatomía & histología , Cráneo/anatomía & histología , Texas , CuevasRESUMEN
Therocephalia are an important clade of non-mammalian therapsids that evolved a diverse array of morphotypes and body sizes throughout their evolutionary history. The postcranial anatomy of therocephalians has largely been overlooked, but remains important towards understanding aspects of their palaeobiology and phylogenetic relationships. Here, we provide the first postcranial description of the large akidnognathid eutherocephalian Moschorhinus kitchingi by examining multiple specimens from fossil collections in South Africa. We also compare the postcranial anatomy with previously described therocephalian postcranial material and provide an updated literature review to ensure a reliable foundation of comparison for future descriptive work. Moschorhinus shares all the postcranial features of eutherocephalians that differentiate them from early-diverging therocephalians, but is differentiated from other eutherocephalian taxa by aspects concerning the scapula, interclavicle, sternum, manus, and femur. The novel anatomical data from this contribution shows that Moschorhinus possessed a stocky bauplan with a particularly robust scapula, humerus, and femur. These attributes, coupled with the short and robust skull bearing enlarged conical canines imply that Moschorhinus was well equipped to grapple with and subdue prey items. Additionally, the combination of these attributes differ from those of similarly sized coeval gorgonopsians, which would have occupied a similar niche in late Permian ecosystems. Moreover, Moschorhinus was the only large carnivore known to have survived the Permo-Triassic mass extinction. Thus, the subtle but important postcranial differences may suggest a type of niche partitioning in the predator guild during the Permo-Triassic mass extinction interval.
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Evolución Biológica , Fósiles , Animales , Sudáfrica , Filogenia , Cráneo/anatomía & histología , Dinosaurios/anatomía & histología , Dinosaurios/fisiología , Huesos/anatomía & histologíaRESUMEN
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.
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Pollos , Cráneo , Animales , Pollos/anatomía & histología , Pollos/genética , Pollos/clasificación , Pollos/fisiología , Cráneo/anatomía & histología , Femenino , MasculinoRESUMEN
At the top of many ecosystems, raptors, also known as birds of prey, hold major influence. They shape their surroundings through their powerful hunting skills and complex interactions with their environment. This study investigates the beak morphology of four prominent raptor species, Golden eagle (Aquila chrysaetos), Common buzzard (Buteo buteo), Peregrine falcon (Falco peregrinus) and Common kestrel (Falco tinnunculus), found in Türkiye. By employing geometric morphometric methods, we investigate shape variations in the beaks of these species to unravel the adaptive significance of their cranial structures. This analysis reveals distinct beak morphologies among the studied raptors, reflecting adaptations to their feeding habits, hunting techniques and ecological niches. The results from Principal component analysis and Canonical variate analysis demonstrate significant differences in beak morphology between the Falconiformes and Accipitriformes clades, as well as among all three groups. The overall mean beak shapes of Golden Eagles are quite similar to Common Buzzards, with both species having longer beaks. In contrast, Falcons exhibit a distinctly different beak morphology, characterized by wider and shorter beaks. Changes in beak shape can lead to changes depending on the skull. It is thought that skull shape variations among predator families may have an impact on beak shape. These findings highlight the importance of integrating morphometric analyses with ecological insights to enhance our understanding of the evolutionary processes shaping raptor beak morphology.
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Pico , Falconiformes , Animales , Pico/anatomía & histología , Falconiformes/anatomía & histología , Falconiformes/fisiología , Rapaces/anatomía & histología , Cráneo/anatomía & histología , Análisis de Componente Principal , Águilas/anatomía & histología , Águilas/fisiología , Conducta Predatoria/fisiología , Especificidad de la EspecieRESUMEN
Sahelanthropus tchadensis has raised much debate since its initial discovery in Chad in 2001, given its controversial classification as the earliest representative of the hominin lineage. This debate extends beyond the phylogenetic position of the species, and includes several aspects of its habitual behavior, especially in what regards its locomotion. The combination of ancestral and derived traits observed in the fossils associated with the species has been used to defend different hypotheses related to its relationship to hominins. Here, the cranial morphology of Sahelanthropus tchadensis was assessed through 16 linear craniometric measurements, and compared to great apes and hominins through Principal Component Analysis based on size and shape and shape information alone. The results show that S. tchadensis share stronger morphological affinities with hominins than with apes for both the analysis that include size information and the one that evaluates shape alone. Since TM 266-01-060-1 shows a strong morphological affinity with the remaining hominins represented in the analysis, our results support the initial interpretations that S. tchadensis represents an early specimen of our lineage or a stem basal lineage more closely related to hominins than to Panini.
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Cefalometría , Fósiles , Hominidae , Cráneo , Animales , Hominidae/anatomía & histología , Hominidae/clasificación , Fósiles/anatomía & histología , Cráneo/anatomía & histología , Análisis de Componente Principal , FilogeniaRESUMEN
Using histological cross-sections, the chondrocranium anatomy was reconstructed for two developmental stages of Hermann's tortoise (Testudo hermanni). The morphology differs from the chondrocrania of most other turtles by a process above the ectochoanal cartilage with Pelodiscus sinensis being the only other known species with such a structure. The anterior and posterior processes of the tectum synoticum are better developed than in most other turtles and an ascending process of the palatoquadrate is missing, which is otherwise only the case in pleurodiran turtles. The nasal region gets proportionally larger during development. We interpret the enlargement of the nasal capsules as an adaption to increase the surface area of the olfactory epithelium for better perception of volant odors. Elongation of the nasal capsules in trionychids, in contrast, is unlikely to be related to olfaction, while it is ambiguous in the case of Sternotherus odoratus. However, we have to conclude that research on chondrocranium anatomy is still at its beginning and more comprehensive detailed descriptions in relation to other parts of the anatomy are needed before providing broad-scale ecological and phylogenetic interpretations.
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Tortugas , Animales , Tortugas/anatomía & histología , Cráneo/anatomía & histología , Cartílago/anatomía & histologíaRESUMEN
Detailed osteological descriptions of the craniomandibular complex of passerine birds are lacking for most species, limiting our understanding of their diversity and evolution. Cowbirds (genus Molothrus) are a small but widespread group of New World nine-primaried songbirds, well-known for their unique brooding parasitic behavior. However, detailed osteological data for cowbirds and other Icteridae are currently scarce and several features of their skulls remain undescribed or poorly known. To address this issue, a detailed comparative osteology of cowbird skulls is presented here for the first time based on data from x-ray microcomputed tomography, dry skeletal data, and multivariate analyses of linear morphometric data. Cowbird skulls offer some functional insights, with many finch-like features probably related to a seed-rich diet that distinguishes them from most other icterids. In addition, features previously overlooked in earlier studies might provide valuable phylogenetic information at different levels of passerine phylogeny (Passerida, Emberizoidea, Icteridae, and Agelaiinae), including some of the otic region and nasal septum. Comparisons among cowbirds show that there is substantial cranial variation within the genus, with M. oryzivorus being the most divergent cowbird species. Within the genus, distantly related species share similar overall skull morphology and proportions, but detailed osteological data allow species identification even in cases of strong convergence. Further efforts are warranted to furnish baseline data for future studies of this iconic group of Neotropical birds and to fully integrate it into phylogenetic comparative frameworks.
Asunto(s)
Cráneo , Microtomografía por Rayos X , Animales , Cráneo/anatomía & histología , Filogenia , Masculino , Osteología , Femenino , Pájaros Cantores/anatomía & histología , Evolución Biológica , Passeriformes/anatomía & histologíaRESUMEN
To determine a rapid and accurate method for locating the keypoint and "keyhole" in the suboccipital retrosigmoid keyhole approach. (1) Twelve adult skull specimens were selected to locate the anatomical landmarks on the external surface of the skull.The line between the infraorbital margin and superior margin of the external acoustic meatus was named the baseline. A coordinate system was established using the baseline and its perpendicular line through the top point of diagastric groove.The perpendicular distance (x), and the horizontal distance (y) between the central point of the "keyhole" and the top point of the digastric groove in that coordinate system were measured. The method was applied to fresh cadaveric specimens and 53 clinical cases to evaluate its application value. (1) x and y were 14.20 ± 2.63 mm and 6.54 ± 1.83 mm, respectively (left) and 14.95 ± 2.53 mm and 6.65 ± 1.61 mm, respectively (right). There was no significant difference between the left and right sides of the skull (P > 0.05). (2) The operative area was satisfactorily exposed in the fresh cadaveric specimens, and no venous sinus injury was observed. (3) In clinical practice, drilling did not cause injury to venous sinuses, the mean diameter of the bone windows was 2.0-2.5 cm, the mean craniotomy time was 26.01 ± 3.46 min, and the transverse and sigmoid sinuses of 47 patients were well-exposed. We propose a "one point, two lines, and two distances" for "keyhole" localization theory, that is we use the baseline between the infraorbital margin and superior margin of the external acoustic meatus and the perpendicular line to the baseline through the top point of the digastric groove to establish a coordinate system. And the drilling point was 14.0 mm above and 6.5 mm behind the top point of the digastric groove in the coordinate system.