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Journal of Morphology Jun 2023A comparative analysis of the forelimb myology of two neotropical procyonids (Nasua nasua and Procyon cancrivorus) was performed to assess how observed differences in...
Functional and phylogenetic interpretation of the forelimb myology of two South American carnivorans, the ring-tailed coati (Nasua nasua) and crab-eating raccoon (Procyon cancrivorus).
A comparative analysis of the forelimb myology of two neotropical procyonids (Nasua nasua and Procyon cancrivorus) was performed to assess how observed differences in their myological configuration would be related to their diverse ecological behaviors and phylogeny. Although both species are associated with the arboreal substrate, N. nasua is a more agile climber that usually digs; whereas P. cancrivorus spends most of its time on the ground foraging, climbing on the trees as shelter and is a good swimmer. Here, myological descriptions, muscle maps, phylogenetic optimizations, and muscle mass data of the forelimb of these two procyonids are presented. The main functional muscular groups are discussed in a comparative framework with other carnivorans that present a wide ecological diversity. Also, muscular characters were mapped onto a phylogeny to explore their evolution and to obtain ancestral state reconstructions. Results indicate clear myological differences among the two neotropical procyonids associated with their ecological preferences. One of the most remarkable anatomical differences is the arrangement and relative mass of the extrinsic musculature, mainly the musculus rhomboideus and the delto-pectoral complexes. In Nasua nasua, these suggested a greater stability in their shoulder girdle for climbing and digging and probably would provide stronger neck and head movements when they use them for foraging on the ground. Conversely, P. cancrivorus has a different extrinsic muscular configuration, which would allow an increment on the stride length and faster movements of the forelimb associated with more frequent terrestrial gaits. Also, significant differences are observed in the distal musculature, associated with strong movements of forepaws when climbing and digging in N. nasua; whereas, P. cancrivorus configuration suggested precise forearm and digits movements, related to manipulation of food items when they are catching prey or feeding. Most of the codified features of P. cancrivorus would reflect retention of plesiomorphies acquired in the common ancestor of caniforms or arctoids, whereas N. nasua shows derived traits, particularly in the proximal forelimb region. The present work increases the information available on the myology of these particular taxa and extant generalized arctoid models in general. The analyses presented here will be useful both for other comparative myological studies (morpho-functional and phylogenetic) and for muscular reconstruction in extinct procyonids, as well as other carnivorans.
Topics: Animals; Procyonidae; Raccoons; Phylogeny; Brachyura; Forelimb; South America
PubMed: 37183491
DOI: 10.1002/jmor.21587 -
Journal of Ultrasound in Medicine :... Oct 2023Ultrasound-guided injections are used to treat common shoulder pathologies and have been shown to be more accurate and effective than traditional landmark-guided...
OBJECTIVES
Ultrasound-guided injections are used to treat common shoulder pathologies and have been shown to be more accurate and effective than traditional landmark-guided procedures. Currently, there exists no inexpensive shoulder model that accurately simulates the anatomical structures of the shoulder while also facilitating glenohumeral joint (GHJ) injection. Our model is an alternative to the traditional bedside training and provides a low-risk training environment.
METHODS
We created this model from easily accessible materials. Polyvinyl chloride pipe was used to create the skeletal infrastructure pectoral girdle. A detergent pod was used to represent the GHJ space. Steaks were used to simulate the infraspinatus and deltoid muscles, with meat glue as a fascial layer between the two simulated muscles. Total cost of materials for the model was $19.71.
RESULTS
Our model successfully replicates known anatomical features of the GHJ. Additionally, the model facilitates injection into a GHJ space, representing a GHJ injection. Our model was replicated to train medical student practitioners during five different educational sessions. The model was validated through comparison to standardized educational ultrasound training videos. It was further validated by ultrasound experts.
CONCLUSIONS
The shoulder model we created is effective in simulating GHJ injections under ultrasound guidance. It simulates realistic muscle and bony landmarks both for ultrasound imaging and injection feel. Importantly, it is inexpensive and easy to replicate allowing more access to medical practitioners and students to be educated on the procedure.
Topics: Humans; Shoulder Joint; Shoulder; Ultrasonography; Injections, Intra-Articular; Ultrasonography, Interventional
PubMed: 37146236
DOI: 10.1002/jum.16253 -
PloS One 2023Cirrhigaleus comprises a small genus of rare barbel-bearing dogfish sharks with distributions in limited regions of all oceans. Generic validity and taxonomic status of...
Untangling the systematic dilemma behind the roughskin spurdog Cirrhigaleus asper (Merrett, 1973) (Chondrichthyes: Squaliformes), with phylogeny of Squalidae and a key to Cirrhigaleus species.
Cirrhigaleus comprises a small genus of rare barbel-bearing dogfish sharks with distributions in limited regions of all oceans. Generic validity and taxonomic status of some species are upon controversies by morphological and molecular evidence that often suggest reallocation of Cirrhigaleus species into the genus Squalus. Particularly, the roughskin spurdog C. asper exhibits intermediary morphological characteristics within Squalidae that requires clarification. In the present study, a phylogenetic approach was undertaken to test the correct generic placement of C. asper using novel and revised morphological characters. We performed maximum parsimony analysis of 51 morphological characters of the internal (e.g., neurocranium, clasper cartilages, pectoral and pelvic girdles) and external anatomy applied to 13 terminal taxa. Cirrhigaleus represents a valid genus and it is supported by eight synapomorphies: high number of monospondylous vertebrae; medial nasal lobe supported by fleshy core and innervated by the buccopharyngeal branch of the facial nerve; neurocranium with greatest width across nasal capsules; one facet and one condyle in the puboischiadic bar for articulating with the basipterygium; two intermediate segments between the basipterygium of the pelvic fin and the axial cartilage of the claspers; five terminal clasper cartilages; and posterior medial process of the puboischiadic bar absent. Cirrhigaleus asper is sister-species to a small clade comprising C. barbifer and C. australis which is supported by one synapomorphy, presence of conspicuous cusplets in the dermal denticles. Cirrhigaleus barbifer, C. asper and C. australis are redescribed herein and the neotype of C. barbifer is designated. A key to Cirrhigaleus species is also given and the inner relationships within Squalus is tentatively discussed.
Topics: Animals; Dogfish; Phylogeny; Sharks; Squalus; Fishes; Blood Group Antigens; Drugs, Generic
PubMed: 36877721
DOI: 10.1371/journal.pone.0282597 -
Anatomical Record (Hoboken, N.J. : 2007) Feb 2023As one of the mysteries volant vertebrates, pterosaurs were completely extinct in the K-Pg extinction event, which hampered our understanding of their flight. Recent...
As one of the mysteries volant vertebrates, pterosaurs were completely extinct in the K-Pg extinction event, which hampered our understanding of their flight. Recent studies on pterosaur flight usually use birds as analogies, since their shoulder girdle share many features. However, it was also proposed that these two groups may differ in some critical flight mechanisms, such as the primary muscles for the upstroke of the wings. Here, we describe and characterize the detail features of the pectoral girdle morphology and histology in Hamipterus from the Early Cretaceous of Northwest China for the first time. Our research reveals that the scapula and coracoid of Hamipterus form a synostosis joint, representing a distinct pectoral girdle adaption during pterosaur flight evolution, different from that of birds. The residual of the articular cartilage of the glenoid fossa supports the potential for cartilage tissue preservation in this location. The morphology of the acrocoracoid process of Hamipterus indicates it may work as a pulley for M. supracoracoideus as the main power of flight upstroke resembles that of birds. But the saddle type of the shoulder joint of the pterosaur may limit the rotation of the humerus head, suggesting a particular mechanism to control the angle of attack unlike birds. The presence of both the similarity and differences between the flight apparatus of pterosaurs and birds are highlighted in our research, which may be related to the flight mechanism and forelimb functional adaption. The distinctive feature of the flight apparatus of pterosaur should be treated with caution in future research, to better understand the life of this unique extinct volant vertebrate.
PubMed: 36787121
DOI: 10.1002/ar.25167 -
The Journal of Experimental Biology Feb 2023Most fish species use concentric epaxial and hypaxial contractions to suction feed, whereby both muscle groups produce cranial expansion and negative intraoral...
Most fish species use concentric epaxial and hypaxial contractions to suction feed, whereby both muscle groups produce cranial expansion and negative intraoral pressures. In contrast, channel catfish (Ictalurus punctatus) suction feed with little to no cranial elevation and epaxial shortening, generating suction power primarily with hypaxial shortening and pectoral girdle retraction. We hypothesized that channel catfish (1) actively anchor the head via isometric contraction of the epaxials and (2) vary feeding performance by modulating the absolute and relative outputs of the co-contracting muscles. We used a combination of electromyography, intraoral pressure recordings and specimen manipulation, and developed a new dual-lever model to explore this idea. We detected epaxial and hypaxial co-contraction prior to suction force development in all strikes. Our model revealed that the differential between the co-contracting muscles may be used to modulate suction pressure and strike accuracy.
Topics: Animals; Muscle, Skeletal; Feeding Behavior; Ictaluridae; Suction; Biomechanical Phenomena
PubMed: 36715010
DOI: 10.1242/jeb.244714 -
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 -
Proceedings of the National Academy of... Jan 2023The Carboniferous (358.9 to 298.9 Ma) saw the emergence of marine ecosystems dominated by modern vertebrate groups, including abundant stem-group holocephalans...
The Carboniferous (358.9 to 298.9 Ma) saw the emergence of marine ecosystems dominated by modern vertebrate groups, including abundant stem-group holocephalans (chimaeras and relatives). Compared with the handful of anatomically conservative holocephalan genera alive today-demersal durophages all-these animals were astonishingly morphologically diverse, and bizarre anatomies in groups such as iniopterygians hint at specialized ecological roles foreshadowing those of the later, suction-feeding neopterygians. However, flattened fossils usually obscure these animals' functional morphologies and how they fitted into these important early ecosystems. Here, we use three-dimensional (3D) methods to show that the musculoskeletal anatomy of the uniquely 3D-preserved iniopterygian can be best interpreted as being similar to that of living holocephalans rather than elasmobranchs but that it was mechanically unsuited to durophagy. Rather, had a small, anteriorly oriented mouth aperture, expandable pharynx, and strong muscular links among the pectoral girdle, neurocranium, and ventral pharynx consistent with high-performance suction feeding, something exhibited by no living holocephalan and never clearly characterized in any of the extinct members of the holocephalan stem-group. Remarkably, in adapting a distinctly holocephalan anatomy to suction feeding, is more comparable to modern tetrapod suction feeders than to the more closely related high-performance suction-feeding elasmobranchs. This raises questions about the assumed role of durophagy in the evolution of holocephalans' distinctive anatomy and offers a rare glimpse into the breadth of ecological niches filled by holocephalans in a pre-neopterygian world.
Topics: Animals; Suction; Ecosystem; Skull; Vertebrates; Fishes; Feeding Behavior
PubMed: 36649436
DOI: 10.1073/pnas.2207854119 -
Anatomical Record (Hoboken, N.J. : 2007) Jul 2023Megaraptora is a group of enigmatic, carnivorous non-avian theropod dinosaurs from the Cretaceous of Asia, Australia, and especially South America. Perhaps the most...
Megaraptora is a group of enigmatic, carnivorous non-avian theropod dinosaurs from the Cretaceous of Asia, Australia, and especially South America. Perhaps the most striking aspect of megaraptoran morphology is the large, robustly constructed forelimb that, in derived members of the clade, terminates in a greatly enlarged manus with hypertrophied, raptorial unguals on the medialmost two digits and a substantially smaller ungual on digit III. The unique forelimb anatomy of megaraptorans was presumably associated with distinctive functional specializations; nevertheless, its paleobiological significance has not been extensively explored. Here we draw from observations of the pectoral girdle and forelimb skeletons of Megaraptora and myological assessments of other archosaurian taxa to provide a comprehensive reconstruction of the musculature of this anatomical region in these singular theropods. Many muscle attachment sites on megaraptoran forelimb bones are remarkably well developed, which in turn suggests that the muscles themselves were functionally significant and important to the paleobiology of these theropods. Furthermore, many of these attachments became increasingly pronounced through megaraptoran evolutionary history, being substantially better developed in derived taxa such as Australovenator wintonensis and especially Megaraptor namunhuaiquii than in early branching forms such as Fukuiraptor kitadaniensis. When considered alongside previous range of motion hypotheses for Australovenator, our results indicate that megaraptorans possessed a morphologically and functionally specialized forelimb that was capable of complex movements. Notable among these were extensive extension and flexion, particularly in the highly derived manus, as well as enhanced humeral protraction, attributes that very probably aided in prey capture.
Topics: Animals; Dinosaurs; Upper Extremity; Biological Evolution; Forelimb; Musculoskeletal System; Fossils
PubMed: 36647300
DOI: 10.1002/ar.25128 -
Homo : Internationale Zeitschrift Fur... Apr 2023Discussions of the evolution of sexual dimorphism in torso shape and the pectoral region assume that this dimorphism exists independently of body size. We test this... (Comparative Study)
Comparative Study
Discussions of the evolution of sexual dimorphism in torso shape and the pectoral region assume that this dimorphism exists independently of body size. We test this assumption in two human populations and further examine what is needed to understand sexual dimorphism in the pectoral region. Modern human males have broad shoulders and narrow hips relative to females, lending males a more triangular torso. The wider female pelvis is commonly attributed to obstetric pressures while the broader male pectoral girdle has been argued to be an adaptation that improves hunting or intrasexual competition. While sexual dimorphism in the pelvic girdle is known to exist after adjusting for body size across human populations, most studies of sexual dimorphism in the pectoral girdle have not adjusted the data to account for sexual size dimorphism or compared different ancestral groups. The aforementioned hypotheses explaining sexual dimorphism in the clavicle and scapula as products of natural selection are predicated on the untested assumption that sex differences do not scale with body size. This study tests this assumption by comparing various measurements of the pectoral girdle, the pelvic girdle, and six pectoral-pelvic indices of black and white South Africans of known sex and height to test whether the sexes and ancestral groups will differ in these values after adjusting for differences in body size. Comparisons of ancestral groups reveal that white South Africans have larger pectoral and pelvic dimensions than black South Africans, but that blacks have larger index values than whites. Regardless of differences in ancestry and body size, males have significantly broader pectoral regions as indicated by comparisons of both individual pectoral measurements and pectoral-pelvic indices. This pattern of sexual dimorphism is reversed in the pelvic region where females have larger skeletal elements. In addition to finding both absolute and relative differences in mean values for the pectoral and pelvic skeleton, females and males and blacks and whites differ in the scaling relationship of these traits, suggesting different allometric trajectories for these bones that may be explained by their distinct evolutionary functions, their adaptations to specific environments, or by changes in lengths due to age. These results suggest that sexual dimorphism in the pectoral region is not a product of scaling and that differences in this region reflect adaptive forces acting in unique ways on each sex, consistent with the assumptions of earlier evolutionary explanations.
Topics: Female; Humans; Male; Black People; Sex Characteristics; Pelvic Bones; White People; South Africa; Bones of Upper Extremity; Race Factors; Sex Factors; Body Height; Biological Evolution
PubMed: 36628541
DOI: 10.1127/homo/2023/1486 -
Anatomical Record (Hoboken, N.J. : 2007) Jun 2023This article presents a detailed comparative analysis of the bone microstructure of three extant species of South American turtles. The main histological characteristics...
Comparative postcranial osteohistology and bone histovariability of aquatic and terrestrial turtles: the case of the South American Phrynops hilarii, Hydromedusa tectifera (Pleurodira, Chelidae), and Chelonoidis chilensis (Cryptodira, Testudinidae).
This article presents a detailed comparative analysis of the bone microstructure of three extant species of South American turtles. The main histological characteristics of postcranial bones are identified, as well as the intraskeletal, ontogenetic and interspecific variation between aquatic and terrestrial species. For this purpose, thin sections of postcranial bones (seventh cervical vertebra, coracoid, scapula, humerus, radius, ulna, ischium, ilium, pubis, femur, tibia, and fibula) of juvenile and adult specimens of aquatic (Phrynops hilarii and Hydromedusa tectifera) and terrestrial (Chelonoidis chilensis) turtles were analyzed. Bone histology revealed an intraskeletal variation of the microanatomical and microstructural organization in these turtles. The cortical bone is composed of poorly vascularized lamellar and parallel-fibered bone tissue interrupted with lines of arrested growth (LAGs), reflecting a cyclical slow growth rate throughout these turtles' life. Although in the adult specimens a growth rate decrease was observed, none of them have reached somatic maturity. The juvenile and the adult of Chelonoidis chilensis, unlike the aquatic species studied, presented a higher vascularization in their bones, which could imply a faster growth rate in this land specie. The number of LAGs was higher in the stylopodial and zeugopodial bones, which would make these elements suitable for approximate age estimations. Pectoral and pelvic girdle bones also exhibited a good record of LAGs. The information here obtained on extant species represents a powerful tool for the interpretation of paleobiological traits present in closely related fossil forms.
Topics: Animals; Turtles; Cortical Bone; Tibia; Humerus; South America
PubMed: 36469456
DOI: 10.1002/ar.25131