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Scientific Reports Mar 2016Fishes have adapted a number of different behaviors to move out of the water, but none have been described as being able to walk on land with a tetrapod-like gait. Here...
Fishes have adapted a number of different behaviors to move out of the water, but none have been described as being able to walk on land with a tetrapod-like gait. Here we show that the blind cavefish Cryptotora thamicola walks and climbs waterfalls with a salamander-like diagonal-couplets lateral sequence gait and has evolved a robust pelvic girdle that shares morphological features associated with terrestrial vertebrates. In all other fishes, the pelvic bones are suspended in a muscular sling or loosely attached to the pectoral girdle anteriorly. In contrast, the pelvic girdle of Cryptotora is a large, broad puboischiadic plate that is joined to the iliac process of a hypertrophied sacral rib; fusion of these bones in tetrapods creates an acetabulum. The vertebral column in the sacral area has large anterior and posterior zygapophyses, transverse processes, and broad neural spines, all of which are associated with terrestrial organisms. The diagonal-couplet lateral sequence gait was accomplished by rotation of the pectoral and pelvic girdles creating a standing wave of the axial body. These findings are significant because they represent the first example of behavioural and morphological adaptation in an extant fish that converges on the tetrapodal walking behaviour and morphology.
Topics: Animals; Biomechanical Phenomena; Fishes; Walking
PubMed: 27010864
DOI: 10.1038/srep23711 -
Journal of Morphology Mar 2017The head is considered the major novelty of the vertebrates and directly linked to their evolutionary success. Its form and development as well as its function, for...
The head is considered the major novelty of the vertebrates and directly linked to their evolutionary success. Its form and development as well as its function, for example in feeding, is of major interest for evolutionary biologists. In this study, we describe the skeletal development of the cranium and pectoral girdle in Siberian (Acipenser baerii) and Russian sturgeon (A. gueldenstaedtii), two species that are commonly farmed in aquaculture and increasingly important in developmental studies. This study comprises the development of the neuro-, viscero- and dermatocranium and the dermal and chondral components of the pectoral girdle, from first condensation of chondrocytes in prehatchlings to the early juvenile stage and reveals a clear pattern in formation. The otic capsules, the parachordal cartilages, and the trabeculae cranii are the first centers of chondrification, at 8.4mm TL. These are followed by the mandibular, then the hyoid, and later the branchial arches. Teeth form early on the dentary, dermopalatine, and palatopterygoid, and then appear later in the buccal cavity as dorsal and ventral toothplates. With ongoing chondrification in the neurocranium a capsule around the brain and a strong rostrum are formed. Dermal ossifications start to form before closure of the dorsal neurocranial fenestrae. Perichondral ossification of cartilage bones occurs much later in ontogeny. Our results contribute data bearing on the homology of elements such as the lateral rostral canal bone that we regard homologous to the antorbital of other actinopterygians based on its sequence of formation, position and form. We further raise doubts on the homology of the posterior ceratobranchial among Actinopteri based on the formation of the hyoid arch elements. We also investigate the basibranchials and the closely associated unidentified gill-arch elements and show that they are not homologous. J. Morphol. 278:418-442, 2017. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Biological Evolution; Bones of Upper Extremity; Branchial Region; Cartilage; Fishes; Hyoid Bone; Osteogenesis; Skull
PubMed: 28176372
DOI: 10.1002/jmor.20653 -
The Journal of Experimental Biology Jun 2006In therian mammals, gravitational and locomotor forces are transferred between the forelimb and trunk primarily, or entirely, through the muscles that connect the limb...
In therian mammals, gravitational and locomotor forces are transferred between the forelimb and trunk primarily, or entirely, through the muscles that connect the limb and trunk. Our understanding of this force transmission is based on analyses of shoulder anatomy and on a handful of descriptive electromyographic studies. To improve our understanding, we manipulated the locomotor forces of trotting dogs and monitored the resulting change in recruitment of five extrinsic muscles of the forelimb: m. serratus ventralis thoracis, m. serratus ventralis cervicis, m. pectoralis superficialis transversus, the anterior portion of the m. pectoralis profundus, and m. rhomboideus thoracis. Locomotor forces were modified as the dogs trotted at constant speed on a motorized treadmill by (1) adding mass to the trunk, (2) inclining the treadmill so that the dogs ran up and down hill, (3) adding mass to the wrists and (4) applying horizontally directed force to the trunk through a leash. These experiments indicate that the thoracic portion of the serratus ventralis muscle is the main antigravity muscle of the shoulder during trotting in dogs. Its activity increased when we added mass to the trunk and also when we ran the subjects downhill. In contrast, the cervical portion of the serratus ventralis did not show a consistent increase in activity in response to added mass. Instead, its activity increased when we ran the subjects up hill and added mass to their wrists, suggesting that it functions to stabilize the fulcrum of the forelimb in the cranial-caudal direction during active retraction of the forelimb. The thoracic portion of the rhomboideus muscle also appears to provide this cranial-caudal stabilization during active retraction of the forelimb. The force manipulations indicate that the transverse pectoralis muscle acts to both protract and retract the forelimb, depending on the position of the limb. In contrast, the anterior portion of the pectoralis profundus muscle acts as a retractor of the forelimb during the end of swing phase and the beginning of support phase. We found that adding mass to the trunk did not increase the activity of forelimb retractor muscles, suggesting that the ground reaction force vector passes through, or very near, the fulcrum of the shoulder during a trotting step. Whether or not the functions of these extrinsic appendicular muscles in dogs characterize therian mammals or represent specializations for high-speed, economical running remains to be determined.
Topics: Animals; Dogs; Forelimb; Gait; Locomotion
PubMed: 16709923
DOI: 10.1242/jeb.02236 -
Journal of the American Veterinary... Nov 2015To evaluate use of a caudoventral-craniodorsal oblique radiographic view made at 45° to the frontal plane (H view) for assessment of the pectoral (thoracic) girdle in...
OBJECTIVE
To evaluate use of a caudoventral-craniodorsal oblique radiographic view made at 45° to the frontal plane (H view) for assessment of the pectoral (thoracic) girdle in raptors.
DESIGN
Retrospective cross-sectional analysis.
ANIMALS
24 raptors suspected to have a fracture of the thoracic girdle.
PROCEDURES
Standard ventrodorsal and H views were obtained for all birds. Radiographs were evaluated twice by a radiologist blinded to the final diagnosis, with each view first evaluated independently and views then evaluated in combination. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated, with results of surgery or necropsy used as the gold standard.
RESULTS
9 birds had thoracic girdle fractures; fractures were correctly identified in 8 of these 9 birds on the ventrodorsal view alone, 7 of these 9 birds on the H view alone, and all 9 birds on the 2 views in combination. Fifteen birds did not have thoracic girdle fractures; radiographs were correctly classified in 12 of these 15 birds when the ventrodorsal view was evaluated alone, all 15 birds when the H view was evaluated alone, and 14 of these 15 birds when the 2 views were evaluated in combination.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that the H view or the addition of the H view to the VD view could be useful in raptors suspected to have fractures of the thoracic girdle. Agreement with the gold standard (ie, fracture present or absent) was higher with the H view and combination of views than with the ventrodorsal view alone.
Topics: Animals; Falconiformes; Fractures, Bone; Radiography; Wings, Animal
PubMed: 26480013
DOI: 10.2460/javma.247.9.1037 -
Integrative Organismal Biology (Oxford,... 2019Mature skates (Batoidea: Rajoidei) display a unique form of sexual dimorphism in which males develop a concave anterior pectoral fin, giving them a bell-shaped...
Mature skates (Batoidea: Rajoidei) display a unique form of sexual dimorphism in which males develop a concave anterior pectoral fin, giving them a bell-shaped appearance. Recent work has linked the male-specific transformation to differential skeletal development that is coincident with the rapid elongation of claspers, cartilage-supported intromittent organs. Still, little is known about the prevalence of pectoral dimorphism across skates or of interspecific variation in its expression. Here, we use various morphological approaches to broadly explore pectoral dimorphism in skates, with the goal of understanding its significance in their evolutionary history. We find that pectoral fin sexual dimorphism exists across skate diversity, positively identifying its presence in at least 131 species spanning 33 genera, approximately 40% of valid species. Further, we show that the nature of male-female shape change is largely consistent across species, but that it differs in its magnitude at a biologically meaningful scale. Finally, we use the pygmy skate as a case study to illustrate ontogenetic patterns in the development of pectoral fin dimorphism, additionally identifying sex-based differences in the pelvic girdle and jaw. Our work suggests that the diversity of pectoral dimorphism in skates is linked to comparative growth and maturation, and potentially to processes underlying reproductive and life history diversification within the group.
PubMed: 33791527
DOI: 10.1093/iob/obz012 -
Evolution; International Journal of... Oct 2015While fore- and hindlimbs are commonly assumed to be serially homologous, the serial homology of the pectoral and pelvic girdles is more ambiguous. We investigate the...
While fore- and hindlimbs are commonly assumed to be serially homologous, the serial homology of the pectoral and pelvic girdles is more ambiguous. We investigate the degree to which a common history, developmental program, and gene network are shared between the girdles relative to the rest of the appendicular skeleton. Paleontological data indicate that pectoral appendages arose millions of years before pelvic appendages. Recent embryological and genetic data suggest that the anatomical similarity between the fore- and hindlimbs arose through the sequential, derived deployment of similar developmental programs and gene networks, and is therefore not due to ancestral serial homology. Much less developmental work has however been published about the girdles. Here, we provide the first detailed review of the developmental programs and gene networks of the pectoral and pelvic girdles. Our review shows that, with respect to these programs and networks, there are fewer similarities between pelvic and pectoral girdles than there are between the limbs. The available data therefore support recent hypotheses that the anatomical similarities between the fore- and hindlimbs arose during the fin-to-limb transition through the derived co-option of similar developmental mechanisms, while the phylogenetically older pectoral and pelvic girdles have remained more distinct since their evolutionary origin.
Topics: Animal Fins; Animals; Biological Evolution; Forelimb; Fossils; Hindlimb; Phylogeny; Vertebrates
PubMed: 26374500
DOI: 10.1111/evo.12773 -
Anatomical Record (Hoboken, N.J. : 2007) Jul 2024Here we present an updated inventory and study of pectoral girdle remains recovered from the Sima de los Huesos (SH) site. Here, we describe the key morphological traits...
Here we present an updated inventory and study of pectoral girdle remains recovered from the Sima de los Huesos (SH) site. Here, we describe the key morphological traits of adults and, for the first time, subadult specimens. Because morphological traits can change with age, we also discuss some shortcomings related to age estimation in postcranial fossil specimens. Adult clavicles from the SH are long with a low robusticity index and marked curvatures in the superior view. Among these traits, only extreme clavicular length seems to characterize subadult individuals. Neandertals share all these traits. In the case of the scapula, the SH specimens share a relatively long and narrow glenoid fossa with Neandertals. This trait is also present in subadult individuals. Additionally, most specimens from SH, adults, and subadults showed a dorsal axillary sulcus on the scapular lateral border, a trait also present in most adult and subadult Neandertals. These traits in adult and subadult specimens supports substantial genetic control for many of them in both human species.
Topics: Animals; Spain; Neanderthals; Humans; Fossils; Clavicle; Scapula; Male; Age Determination by Skeleton; Adult; Female
PubMed: 36656646
DOI: 10.1002/ar.25158 -
Anatomical Science International Mar 2012The evolution of the turtle shell has long been one of the central debates in comparative anatomy. The turtle shell consists of dorsal and ventral parts: the carapace... (Review)
Review
The evolution of the turtle shell has long been one of the central debates in comparative anatomy. The turtle shell consists of dorsal and ventral parts: the carapace and plastron, respectively. The basic structure of the carapace comprises vertebrae and ribs. The pectoral girdle of turtles sits inside the carapace or the rib cage, in striking contrast to the body plan of other tetrapods. Due to this topological change in the arrangement of skeletal elements, the carapace has been regarded as an example of evolutionary novelty that violates the ancestral body plan of tetrapods. Comparing the spatial relationships of anatomical structures in the embryos of turtles and other amniotes, we have shown that the topology of the musculoskeletal system is largely conserved even in turtles. The positional changes seen in the ribs and pectoral girdle can be ascribed to turtle-specific folding of the lateral body wall in the late developmental stages. Whereas the ribs of other amniotes grow from the axial domain to the lateral body wall, turtle ribs remain arrested axially. Marginal growth of the axial domain in turtle embryos brings the morphologically short ribs in to cover the scapula dorsocaudally. This concentric growth appears to be induced by the margin of the carapace, which involves an ancestral gene expression cascade in a new location. These comparative developmental data allow us to hypothesize the gradual evolution of turtles, which is consistent with the recent finding of a transitional fossil animal, Odontochelys, which did not have the carapace but already possessed the plastron.
Topics: Animal Shells; Animals; Biological Evolution; Body Patterning; Chick Embryo; Embryo, Nonmammalian; Turtles
PubMed: 22131042
DOI: 10.1007/s12565-011-0121-y -
Journal of Anatomy Nov 2020Birds have lost and modified the musculature joining the pectoral girdle to the skull and hyoid, called the pectoral extrinsic appendicular and infrahyoid musculature....
Birds have lost and modified the musculature joining the pectoral girdle to the skull and hyoid, called the pectoral extrinsic appendicular and infrahyoid musculature. These muscles include the levator scapulae, sternomandibularis, sternohyoideus, episternocleidomastoideus, trapezius, and omohyoideus. As non-avian theropod dinosaurs are the closest relatives to birds, it is worth investigating what conditions they may have exhibited to learn when and how these muscles were lost or modified. Using extant phylogenetic bracketing, osteological correlates and non-osteological influences of these muscles are identified and discussed. Compsognathids and basal Maniraptoriformes were found to have been the likeliest transition points of a derived avian condition of losing or modifying these muscles. Increasing needs to control the feather tracts of the neck and shoulder, for insulation, display, or tightening/readjustment of the skin after dynamic neck movements may have been the selective force that drove some of these muscles to be modified into dermo-osseous muscles. The loss and modification of shoulder protractors created a more immobile girdle that would later be advantageous for flight in birds. The loss of the infrahyoid muscles freed the hyolarynx, trachea, and esophagus which may have aided in vocal tract filtering.
Topics: Animals; Biological Evolution; Birds; Dinosaurs; Muscle, Skeletal
PubMed: 32794182
DOI: 10.1111/joa.13256 -
Journal of Morphology Aug 2001The configuration of the pectoral girdle bones and muscles of numerous catfishes was studied in detail and compared with that of other siluriforms, as well as of other... (Comparative Study)
Comparative Study
The configuration of the pectoral girdle bones and muscles of numerous catfishes was studied in detail and compared with that of other siluriforms, as well as of other teleosts, described in the literature. The pectoral girdle of catfishes is composed of only three bones, which probably correspond to the posttemporo-supracleithrum (posttemporal + supracleithrum), scapulo-coracoid (scapula + coracoid), and cleithrum of other teleosts. These latter two bones constitute the place of origin of the pectoral girdle muscles. Two of these muscles are related to the movements of the pectoral fin. These two muscles correspond, very likely, to the abductor superficialis and to the adductor superficialis of other teleostean fishes. In relation to the pectoral spine (thickened first pectoral fin ray), it is usually moved by three well-developed muscles, which are probably homologous with the arrector ventralis, arrector dorsalis, and abductor profundus of nonsiluriform teleosts. The morphological diversity and the plesiomorphic configuration of these muscles, as well as of the other catfish pectoral girdle structures, are discussed.
Topics: Animals; Bone and Bones; Catfishes; Pectoralis Muscles; Phylogeny; Shoulder Joint; Swimming
PubMed: 11466739
DOI: 10.1002/jmor.1043