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1.
Vinyard CJ 《American journal of primatology》2007,69(1):46-58
The primate masticatory apparatus (MA) is a functionally integrated set of features, each of which performs important functions in biting, ingestive, and chewing behaviors. A comparison of morphological covariance structure among species for these MA features will help us to further understand the evolutionary history of this region. In this exploratory analysis, the covariance structure of the MA is compared across seven galago species to investigate 1) whether there are differences in covariance structure in this region, and 2) if so, how has this covariation changed with respect to size, MA form, diet, and/or phylogeny? Ten measurements of the MA functionally related to bite force production and load resistance were obtained from 218 adults of seven galago species. Correlation matrices were generated for these 10 dimensions and compared among species via matrix correlations and Mantel tests. Subsequently, pairwise covariance disparity in the MA was estimated as a measure of difference in covariance structure between species. Covariance disparity estimates were correlated with pairwise distances related to differences in body size, MA size and shape, genetic distance (based on cytochrome‐b sequences) and percentage of dietary foods to determine whether one or more of these factors is linked to differences in covariance structure. Galagos differ in MA covariance structure. Body size appears to be a major factor correlated with differences in covariance structure among galagos. The largest galago species, Otolemur crassicaudatus, exhibits large differences in body mass and covariance structure relative to other galagos, and thus plays a primary role in creating this association. MA size and shape do not correlate with covariance structure when body mass is held constant. Diet also shows no association. Genetic distance is significantly negatively correlated with covariance disparity when body mass is held constant, but this correlation appears to be a function of the small body size and large genetic distance for Galagoides demidoff. These exploratory results indicate that changing body size may have been a key factor in the evolution of the galago MA. Am. J. Primatol. 69:46–58, 2007. © 2006 Wiley‐Liss, Inc. 相似文献
2.
We describe the ontogeny of the axial skeleton and median fins of the Southeast Asian freshwater puffer Monotrete leiurus, based on a reared developmental series. Most elements of the axial skeleton in M. leiurus arise in membrane bone. Only the base of the anterior three neural arches, the base of the hemal arches of the third preural centrum, the neural and hemal arches and spines of the second preural centrum, the parhypural, the two hypural plates, and the single epural are preformed in cartilage. In contrast to most teleosts, the proximal-middle radials of the dorsal and anal fins are upright and symmetrical and their distal tips coalesce during development to form a deep band of cartilage, from which the spherical distal radials are spatially separated. 相似文献
3.
Hylander WL Wall CE Vinyard CJ Ross C Ravosa MR Williams SH Johnson KR 《American journal of physical anthropology》2005,128(1):35-56
The major purpose of this study is to analyze anterior and posterior temporalis muscle force recruitment and firing patterns in various anthropoid and strepsirrhine primates. There are two specific goals for this project. First, we test the hypothesis that in addition to transversely directed muscle force, the evolution of symphyseal fusion in primates may also be linked to vertically directed balancing-side muscle force during chewing (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469-492). Second, we test the hypothesis of whether strepsirrhines retain the hypothesized primitive mammalian condition for the firing of the anterior temporalis, whereas anthropoids have the derived condition (Weijs [1994] Biomechanics of Feeding in Vertebrates; Berlin: Springer-Verlag, p. 282-320). Electromyographic (EMG) activities of the left and right anterior and posterior temporalis muscles were recorded and analyzed in baboons, macaques, owl monkeys, thick-tailed galagos, and ring-tailed lemurs. In addition, as we used the working-side superficial masseter as a reference muscle, we also recorded and analyzed EMG activity of the left and right superficial masseter in these primates. The data for the anterior temporalis provided no support for the hypothesis that symphyseal fusion in primates is linked to vertically directed jaw muscle forces during mastication. Thus, symphyseal fusion in primates is most likely mainly linked to the timing and recruitment of transversely directed forces from the balancing-side deep masseter (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469-492). In addition, our data demonstrate that the firing patterns for the working- and balancing-side anterior temporalis muscles are near identical in both strepsirrhines and anthropoids. Their working- and balancing-side anterior temporalis muscles fire asynchronously and reach peak activity during the power stroke. Similarly, their working- and balancing-side posterior temporalis muscles also fire asynchronously and reach peak activity during the power stroke. Compared to these strepsirrhines, however, the balancing-side posterior temporalis of anthropoids appears to have a relatively delayed firing pattern. Moreover, based on their smaller W/B ratios, anthropoids demonstrate a relative increase in muscle-force recruitment of the balancing-side posterior temporalis. This in turn suggests that anthropoids may emphasize the duration and magnitude of the power stroke during mastication. This hypothesis, however, requires additional testing. Furthermore, during the latter portion of the power stroke, the late activity of the balancing-side posterior temporalis of anthropoids apparently assists the balancing-side deep masseter in driving the working-side molars through the terminal portion of occlusion. 相似文献
4.
《Journal of morphology》2017,278(9):1262-1283
A variety of vertebral centrum morphologies have evolved within early tetrapods which range from multipartite centra consisting of intercentra and pleurocentra in stem‐tetrapods, temnospondyls, seymouriamorphs, and anthracosaurs up to monospondylous centra in lepospondyls. With the present study, we aim to determine the formation of both intercentrum and pleurocentrum and asked whether these can be homologized based on their bone histology. Both intercentra and pleurocentra ossified endochondrally and periosteal bone was subsequently deposited on the outer surface of the centra. Our observations indicate low histological variation between intercentrum and pleurocentrum in microstructural organization and growth which inhibits the determination of homologies. However, intercentrum and pleurocentrum development differs during ontogeny. As previously assumed, the intercentrum arises from ventrally located and initially paired ossification centers that fuse ventromedially to form the typical, crescentic, rhachitomous intercentrum. In contrast, presacral pleurocentra may be ancestrally represented by four ossification centers: a ventral and a dorsal pair. Subsequently, two divergent developmental patterns are observed: In stem‐tetrapods and temnospondyls, the pleurocentrum evolves from the two dorsally located ossification centers which may occasionally fuse to form a dorsal crescent. In some dvinosaurian temnospondyls, the pleurocentrum may even ossify to full rings. In comparison, the pleurocentrum of stem‐amniotes (anthracosaurs, chroniosuchids, seymouriamorphs, and lepospondyls) arises from the two ventrally located ossification centers whereby the ossification pattern is almost identical to that of temnospondyls but mirror‐inverted. Thus, the ring‐shaped pleurocentrum of Discosauriscus ossifies from ventral to dorsal. We also propose that the ossified portions of the intercentrum and pleurocentrum continued as cartilaginous rings or discs that surrounded the notochord in the living animals. 相似文献
5.
WALTER STALKER GREAVES 《Zoological Journal of the Linnean Society》2008,153(3):625-629
A few orders of mammals contain many individuals with dominant masseter and pterygoid muscles that pull up and forward as they close the jaw. A dominant temporalis muscle that pulls the jaw up and to the rear is the more common condition in mammals. A long toothless region (diastema) is present in almost all mammals with a large masseter/pterygoid complex. The presence of a diastema, when few teeth have been lost and their size has not changed significantly over evolutionary time, implies that the jaws have lengthened, as in horses and selenodont artiodactyls. (A long jaw with a shorter diastema will also form if very long incisors develop as in rodents.) The sum of the forces of all the jaw muscles (represented by an arrow) typically divides the jaw into a posterior, toothless region and an anterior region where the teeth are located. In most mammals, the sum of all the bite forces at the teeth is maximized when the lengths of the projections of these two regions, onto a line perpendicular to the arrow, are in the ratio of 3 : 7. If the tooth-bearing region of the jaws becomes longer over evolutionary time this ratio will obviously be disturbed. A change in the location of some basic bony features of the jaw mechanism could maintain this ratio, but this requires major disruption of the skull and jaws. Alternatively, simply changing the masses of the muscles that close the jaw (smaller temporalis, larger masseter and/or pterygoid, or some combination), so that the lower jaw is pulled up and forward, rather than backward, also maintains the ratio. According to this view, if the jaw lengthens over evolutionary time, the relative sizes of the jaw muscles will change so that the masseter/pterygoid complex will become dominant. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 153 , 625–629. 相似文献
6.
Bite force was quantified for 13 species of North American rodents using a piezo-resistive sensor. Most of the species measured (11) formed a tight relationship between body mass and bite force (log 10(bite force)=0.43(log 10(body mass))+0.416; R 2 >0.98). This high correlation exists despite the ecological (omnivores, grazers and more carnivorous) and taxonomic (Cricetidae, Heteromyidae, Sciuridae and Zapodidae) diversity of species. Two additional species, Geomys bursarius (Geomyidae) and a Sciurus niger (Sciuridae), bit much harder for their size. We found a simple index of strength based on two measurements of the incisor at the level of the alveolus ( Zi =((anterior-posterior length)2 × (medial-lateral width))/6) that is highly predictive of bite force in these rodents (R2 >0.96). Zi may be useful for prediction of bite force (log10 (Bite Force)=0.566log10 ( Zi )+1.432) when direct measurements are not available. 相似文献
7.
The robust skull and highly subdivided adductor mandibulae muscles of triggerfishes provide an excellent system within which to analyze the evolutionary processes underlying phenotypic diversification. We surveyed the anatomical diversity of balistid jaws using Procrustes‐based geometric morphometric analyses and a phylomorphospace approach to quantifying morphological transformation through evolution. We hypothesized that metrics of interspecific cranial shape would reveal patterns of phylogenetic diversification that are congruent with functional and ecological transformation. Morphological landmarks outlining skull and adductor mandibulae muscle shape were collected from 27 triggerfish species. Procrustes‐transformed skull shape configurations revealed significant phylogenetic and size‐influenced structure. Phylomorphospace plots of cranial shape diversity reveal groupings of shape between different species of triggerfish that are mostly consistent with phylogenetic relatedness. Repeated instances of convergence upon similar cranial shape by genetically disparate taxa are likely due to the functional demands of shared specialized dietary habits. This study shows that the diversification of triggerfish skulls occurs via modifications of cranial silhouette and the positioning of subdivided jaw adductor muscles. Using the morphometric data collected here as input to a biomechanical model of triggerfish jaw function, we find that subdivided jaw adductors, in conjunction with a unique cranial skeleton, have direct biomechanical consequences that are not always congruent with phylomorphospace patterns in the triggerfish lineage. The integration of geometric morphometrics with biomechanical modeling in a phylogenetic context provides novel insight into the evolutionary patterns and ecological role of muscle subdivisions in triggerfishes. J. Morphol. 277:737–752, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
8.
Aldo Iván Vassallo 《Journal of morphology》2016,277(7):879-887
Bone strength is determined by the mechanical properties of bone material, and the size and shape of the whole bone, i.e., its architecture. The mandible of vertebrates has been traditionally regarded as a beam oriented in relation to main masticatory loads, i.e., the longer dimension of its cross‐section being parallel to the load. Rodents follow this pattern but, in addition, their mandible possesses an intriguing arch‐like shape that is apparent when seen in the lateral view. Little attention was given to the structural capacity of this trait. The advantage of an arch is that it can withstand a greater load than a horizontal beam. The objective of this study was to model the rodent mandible like an arch to evaluate its structural strength. The bending moment in an arch‐like mandible was 15–25% lower with respect to a beam‐like mandible. Further, bending varies with mandible “slenderness” and incisor procumbency, a functionally relevant rodent trait. In the rodent Ctenomys talarum (Caviomorpha; Ctenomyidae), bone stress was substantially reduced when the mandible was modeled as an arch‐like structure as compared with a beam‐like structure, and safety factors were 15–34% higher. The shape of rodents' mandible might confer a functional advantage to high and repeatedly applied loads resulting from a unique feeding mode: gnawing. J. Morphol. 277:879–887, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
9.
N. Solounias 《Journal of Zoology》1999,247(2):257-268
10.
A cervical human vertebra of a young adult, corresponding to the Mousterian period (70,000–40,000 B.P.) excavated from the Hayonim Cave in Israel, is described here. Its morphological characteristics, size and shape, do not differ from corresponding vertebrae of present-day man. This gives further support to the concept that some ancient populations of the Mousterian period of Israel were very similar to modern man. 相似文献
11.
Thierra K. Nalley Neysa Grider-Potter 《American journal of physical anthropology》2015,156(4):531-542
The vertebral column plays a key role in maintaining posture, locomotion, and transmitting loads between body components. Cervical vertebrae act as a bridge between the torso and head and play a crucial role in the maintenance of head position and the visual field. Despite its importance in positional behaviors, the functional morphology of the cervical region remains poorly understood, particularly in comparison to the thoracic and lumbar sections of the spinal column. This study tests whether morphological variation in the primate cervical vertebrae correlates with differences in postural behavior. Phylogenetic generalized least-squares analyses were performed on a taxonomically broad sample of 26 extant primate taxa to test the link between vertebral morphology and posture. Kinematic data on primate head and neck postures were used instead of behavioral categories in an effort to provide a more direct analysis of our functional hypothesis. Results provide evidence for a function-form link between cervical vertebral shape and postural behaviors. Specifically, taxa with more pronograde heads and necks and less kyphotic orbits exhibit cervical vertebrae with longer spinous processes, indicating increased mechanical advantage for deep nuchal musculature, and craniocaudally longer vertebral bodies and more coronally oriented zygapophyseal articular facets, suggesting an emphasis on curve formation and maintenance within the cervical lordosis, coupled with a greater resistance to translation and ventral displacement. These results not only document support for functional relationships in cervical vertebrae features across a wide range of primate taxa, but highlight the utility of quantitative behavioral data in functional investigations. Am J Phys Anthropol 156:531–542, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
12.
Robert Holmes 《Historical Biology》2013,25(2):111-124
Previous attempts to analyze structure‐function relationships of vertebral centrum patterns in Paleozoic amphibians have been too simplistic and led to vague conclusions. Vertebral movements, as in the human spine, were coupled. Movements and flexibility of the column were correlated with zygapophysis orientation. The essentially notochordal centrum of early tetrapods permitted several widely divergent patterns to arise without compromising load‐bearing capacity. As the osseous centrum became more robust to assume a greater supportive role in later tetrapods, there was less opportunity to remodel its structure. The seymouriamorph pattern permitted limited axial rotation in association with lateral flexure, while the rhachitomous pattern permitted extended axial rotation in association with lateral flexure by distributing movements within its multipartate centrum. The persistence of widely divergent vertebral configurations, regardless of habitat, in later Paleozoic amphibians can be explained at least partly in terms of historical constraint rather than in strict adaptationist terms. 相似文献
13.
The majority of reported pathologies in lissamphibians (salamanders, caecilians and frogs) include limb deformities such as missing limbs, multiple extra limbs and digits, or incomplete limb formation. However, comparatively little is known about congenital vertebral malformations or posttraumatic pathologies (e.g. injuries, infections) in the vertebral column of salamanders. In the present study, we describe eight vertebral deformities in three cleared and stained specimens of Desmognathus fuscus. Two specimens display developmental deformities which range from a potential non-segmented wedge vertebra to fully segmented hemivertebrae. The vertebral pathology in the third specimens possibly results from a parasitic infection. Apparently, these osseous deformities were not severe enough to prohibit survival of the specimens. 相似文献
14.
Kazushige Tanabe Akihiro Misaki Neil H. Landman Taichi Kato 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2013,46(3):399-408
The jaw apparatuses of two species of Late Cretaceous Phylloceratina (Ammonoidea), Hypophylloceras subramosum and Phyllopachyceras ezoensis, are described on the basis of well‐preserved in situ material from Hokkaido, Japan. Gross morphological and X‐ray CT observations reveal that the upper and lower jaws of the two species are essentially similar in their overall structure. Their upper jaws consist of a shorter outer lamella and a pair of larger, wing‐like inner lamellae that become narrower and join together in the anterior portion, as in those of other ammonoids. The upper jaws of the two phylloceratid species are, however, distinguishable from those of other known ammonoids by the presence of a thick, arrowhead‐shaped calcified rostral tip. The lower jaws of the two species consist of a short, reduced inner lamella and a large, gently convex outer lamella covered with a thin calcareous layer, the features of which are common with the rhynchaptychus‐type lower jaws of the Cretaceous Lytoceratina. In the presence of a sharply pointed, thick calcareous tip on upper and lower jaws, the jaw apparatuses of the Phylloceratina resemble those of modern and fossil nautilids, suggesting that they were developed to serve a scavenging predatory feeding habit in deeper marine environments. This and other studies demonstrate that at least some Mesozoic rhyncholites and conchorhynchs are attributable to the Phylloceratina and Lytoceratina. 相似文献
15.
When animals grow, the functional demands that they experience often change as a consequence of their increasing body size. In this study, we examined the feeding biomechanics in esocid species that represent different size classes (small, Esox americanus; intermediate, Esox niger; large, Esox lucius), and how their bite forces and associated functional variables change as they grow. In order to evaluate bite performance through ontogeny, we dissected and measured dimensions of the feeding apparatus and the adductor mandibulae muscle complex with its segmentum facialis subdivisions such as the ricto‐malaris, stegalis and endoricto‐malaris across a wide range of body sizes. The collected morphological data was used as input variables for a published anatomical model to simulate jaw function in these fish species. Maximum bite forces for both anterior bite and posterior bite increased in isometry in E. americanus and E. niger. The posterior bite of E. lucius also increases in isometry, however, the anterior bite increases in positive allometry. Intraspecific comparison within E. lucius indicated the increase of bite forces in more developed individuals accelerated after the fish grew out of fingerling stage. In addition, our analysis indicated functional differentiation between subdivisions of the adductor mandibulae segmentum facialis, as well as interspecific differences in the pattern of contribution to the bite performance by these subdivisions. Our study provides insights into not only the musculoskeletal basis of the jaw function of esocid species, but also the feeding capacity of this species in relation to the functional demands it faces as one of the top predators in lake and river systems. J. Morphol. 277:1447–1458, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
16.
Philip J. Motta Robert E. Hueter Timothy C. Tricas Adam P. Summers Daniel R. Huber Dayv Lowry Kyle R. Mara Michael P. Matott Lisa B. Whitenack Alpa P. Wintzer 《Journal of morphology》2008,269(9):1041-1055
The nurse shark, Ginglymostoma cirratum, is an obligate suction feeder that preys on benthic invertebrates and fish. Its cranial morphology exhibits a suite of structural and functional modifications that facilitate this mode of prey capture. During suction‐feeding, subambient pressure is generated by the ventral expansion of the hyoid apparatus and the floor of its buccopharyngeal cavity. As in suction‐feeding bony fishes, the nurse shark exhibits expansive, compressive, and recovery kinematic phases that produce posterior‐directed water flow through the buccopharyngeal cavity. However, there is generally neither a preparatory phase nor cranial elevation. Suction is generated by the rapid depression of the buccopharyngeal floor by the coracoarcualis, coracohyoideus, and coracobranchiales muscles. Because the hyoid arch of G. cirratum is loosely connected to the mandible, contraction of the rectus cervicis muscle group can greatly depress the floor of the buccopharyngeal cavity below the depressed mandible, resulting in large volumetric expansion. Suction pressures in the nurse shark vary greatly, but include the greatest subambient pressures reported for an aquatic‐feeding vertebrate. Maximum suction pressure does not appear to be related to shark size, but is correlated with the rate of buccopharyngeal expansion. As in suction‐feeding bony fishes, suction in the nurse shark is only effective within approximately 3 cm in front of the mouth. The foraging behavior of this shark is most likely constrained to ambushing or stalking due to the exponential decay of effective suction in front of the mouth. Prey capture may be facilitated by foraging within reef confines and close to the substrate, which can enhance the effective suction distance, or by foraging at night when it can more closely approach prey. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc. 相似文献
17.
18.
Jennifer M. Manjakasy Ryan D. Day Anne Kemp Ian R. Tibbetts 《Journal of morphology》2009,270(10):1155-1165
Belonidae are unusual in that they are carnivorous but lack a stomach and have a straight, short gut. To develop a functional morphological model for this unusual system the gut contents and alimentary tract morphology of Tylosurus gavialoides and Strongylura leiura ferox were investigated. The posterior orientation of the majority of the pharyngeal teeth supports the swallowing of whole large prey, but not their mastication. Mucogenic cells are abundant in the mucosa lining, particularly the esophagus, and their secretions are likely to protect the gut lining from damage while lubricating passage of the prey. Esophagus, anterior intestine, posterior intestine, and rectum all have highly reticulate mucosae. The anterior three gut sections are distensible to accommodate the passage of prey. However, following ingestion large prey are passed to the highly distensible posterior intestine where they rest head first against the ileorectal valve. Alimentary pH ranges from neutral to weakly acidic. Fish prey is digested head first with the head being largely digested while the remainder of the body is still intact. The nondistensibility of the rectum and the small aperture provided by the ileorectal valve suggest the products of intestinal digestion are either small particulates or fluids that pass into rectum where they are absorbed. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc. 相似文献
19.
Wilson A Lichtwark G 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2011,366(1570):1540-1553
The arrangement of muscles and tendons has been studied in detail by anatomists, surgeons and biomechanists for over a century, and the energetics and mechanics of muscle contraction for almost as long. Investigation of how muscles function during locomotion and the relative length change in muscle fibres and the associated elastic tendon has, however, been more challenging. In recent years, novel in vivo measurement methods such as ultrasound and sonomicrometry have contributed to our understanding of the dynamics of the muscle tendon unit during locomotion. Here, we examine both published and new data to explore how muscles are arranged to deliver the wide repertoire of locomotor function and the trade-offs between performance and economy that result. 相似文献
20.
Barros KM Manhaes-de-Castro R Goubel F Canon F 《Animal : an international journal of animal bioscience》2009,3(1):72-78
During the post-weaning growth and maturation period (25/90 days after birth), rat limb muscles are submitted to specific adaptations. Our aim was to characterize the mechanical properties of two muscles that are opposite in terms of fibre-type distribution, the soleus and the extensor digitorum longus (EDL) muscles of male Wistar rats. Results showed a fast-to-slow fibre-type transition in soleus while no modification in fibre-type distribution was observed in EDL. A growth-induced increase in muscle force was observed. Soleus underwent an increase in twitch kinetics, but EDL showed no modification. Resistance to fatigue was higher in 90-day-old soleus but not modified in the EDL. Surprisingly, analysis of maximal shortening velocity showed a decrease in both soleus and EDL. Finally, tension/extension curves indicated a growth-induced increase in series elastic stiffness in the two muscles. These results suggest that during this growth period, skeletal muscles are submitted to differential adaptations. Moreover, whereas adaptation of biomechanical properties observed can be explained partly by an adaptation of fibre profile in soleus, this is not the case for EDL. It is suggested that changes in muscle architecture, which are often disregarded, could explain some variations in mechanical properties, especially when muscles undergo an increase in both mass and length. 相似文献