The postcranial skeleton of the Lower Jurassic eosuchian Gephyrosaurus bridensis

The postcranial skeleton of the reptile Gephyrosaurus bridensis is described. The material was extracted from the Lower Jurassic fissure infillings of South Wales and comprises the broken and dissociated bones of many different individuals. The skeleton, like the skull, retains many primitive features which justify the inclusion of Gephyrosaurus within the Eosuchia. A comparison of the skeleton with that of other genera supports the conclusion that Gephyrosaurus represents a separate eosuchian lineage. The skeleton is that of a small, unspecialized terrestrial reptile which could move quickly in pursuit of prey.     

Patterns of morphological integration in the appendicular skeleton of mammalian carnivores

We investigated patterns of evolutionary integration in the appendicular skeleton of mammalian carnivores. The findings are discussed in relation to performance selection in terms of organismal function as a potential mechanism underlying integration. Interspecific shape covariation was quantified by two‐block partial least‐squares (2B‐PLS) analysis of 3D landmark data within a phylogenetic context. Specifically, we compared pairs of anatomically connected bones (within‐limbs) and pairs of both serially homologous and functional equivalent bones (between‐limbs). The statistical results of all the comparisons suggest that the carnivoran appendicular skeleton is highly integrated. Strikingly, the main shape covariation relates to bone robustness in all cases. A bootstrap test was used to compare the degree of integration between specialized cursorial taxa (i.e., those whose forelimbs are primarily involved in locomotion) and noncursorial species (i.e., those whose forelimbs are involved in more functions than their hindlimb) showed that cursors have a more integrated appendicular skeleton than noncursors. The findings demonstrate that natural selection can influence the pattern and degree of morphological integration by increasing the degree of bone shape covariation in parallel to ecological specialization.     

Osteocranial development in the viviparous surfperch Amphistichus argenteus (pisces: Embiotocidae)

The development of the cranial and branchial skeleton of the surfperch Amphistichus argenteus, a member of the family Embiotocidae, is described, and phylogenetic and functional aspects of the skull development of this species are discussed. The earliest bones to appear are those dermal elements of the branchial skeleton involved with feeding, and the bones, both dermal and endochondral, located in the basicranial region of the neurocranium. These are followed by dermal bones associated with the lateral line system and finally by the remainder of the bones of the branchial skeleton and the cartilaginous bones of the otic capsules. The last bone to develop is the ethmoid.     

The specificity of the deposition of intratracheally administered plutonium in different skeletal bones with a change in iron homeostasis]

A study was made of the distribution of plutonium-239 injected intratracheally within different bones of the skeleton, the iron status in the blood being changed. The iron preparation caused a 2.5-3-fold decrease in the plutonium loading onto cancellous bone tissue that displayed, in ordinary conditions, a higher tropism to the radionuclide than a cortical highly mineralized bone did.     

(鱼句)亚科花(鱼骨)型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。     

A Late Woodland Burial from Platte County,Missouri

Abstract

A skeleton of a female discovered in a grave located on the west bank of Short Creek, Platte County, Missouri provides some of the first evidence for mortuary practices and human morphology for the Western Missouri-Eastern Kansas Late Woodland. The burial is a bundle type, with most of the bones placed in a central heap. Analysis of the distribution of the bones indicates that some soh tissue was still adhering to the skeleton at the time of the secondary burial. Bones of the right hand and foot and the vertebral column from cervical 7 to the coccyx are the only remains preserved in anatomical order. Many of the long bones appear to have been broken and there is also some evidence for burning and fleshing of the skeleton before final interment. Measurements of the cranial and post-cranial skeleton are given for comparison with future Late Woodland discoveries.     

FGFs in endochondral skeletal development

The mammalian skeleton developments and grows through two complementary pathways: membranous ossification, which gives rise to the calvarial bones and distal clavicle, and endochondral ossification, which is responsible for the bones of the limbs, girdles, vertebrae, face and base of the skull and the medial clavicle. Fibroblast growth factors (FGFs) and their cognate FGF receptors (FGFRs) play important roles in regulating both pathways. However, the details of how FGF signals are initiated, propagated and modulated within the developing skeleton are only slowly emerging. This prospect will focus on the current understanding of these events during endochondral skeletal development with special attention given to concepts that have emerged in the past few years. J. Cell. Biochem. 110: 1046–1057, 2010. Published 2010 Wiley‐Liss, Inc.     

Allometry and curvature in the long bones of quadrupedal mammals

The allometric relationships between basic structural proportions in long bones are examined in the humerus, radius, femur and tibia for a diverse group of 42 terrestrial quadrupedal mammals that span a size range from 0.02–6000 kg. Non-linear scaling is found for length vs. diameter in the tibia and radius, suggesting that the mechanical constraints on the skeleton differ within large and small body-size mammals. Curvature normalized to mid-shaft radius scales differently in the different long bones. Curvature is poorly related to size in the proximal limb bones (humerus and femur) while it decreases systematically with size in the tibia (mass exponent −0.13). The scaling of normalized curvature in the radius is unique among long bones. Variability of curvature in the radius is reduced at any size in comparison to that found in the other long bones. Normalized curvature is constant within the small body size group (0.02 to approximately 100 kg) while it decreases sharply with size within animals over 100 kg body mass. The unusual scaling found in the radius is probably the result of this bone's close alignment with the extrinsic forces which act on it during locomotion. The change in scaling within the radius for animals of different size may be indicative of more general size-dependent mechanical trade-offs which are masked by the complex loading circumstances of the other long bones.     

Age-related changes and secular trends in hand bone size

The aim of the present study was to evaluate age- and sex-related changes in the size and shape of long hand bones in a large Chuvashian cohort using cross-sectional and longitudinal study designs. The data were gathered in 1994 (557 individuals) and 2002 (513 individuals). The latter sample included 260 individuals that were studied only during the second expedition, and 253 individuals who were previously investigated in 1994. Statistical analyses included a maximum likelihood-based model-fitting technique and a t-test comparison. We found evidence for secular trend of hand bone size in both males and females within the Chuvashian population. In males, the length and total area of the long hand bones were greater in younger individuals, but mid-shaft bone width remained almost the same in individuals born at different periods of the last century. In females, the length of the hand bones and total bone area remained unchanged in women born after 1937. However, bone mid-shaft width gradually decreased in women born after 1940. Therefore, we argue that, at least within the Chuvashian population, there is a secular trend towards a more gracile appendicular skeleton in both males and females.     

Retention and dosimetry of injected 241Am in beagles

Equations have been derived, from the results of total-body and partial-body counting and gamma-ray counting of individual bones and soft tissues, which describe the retention of injected 241Am in the liver, in the nonliver tissue (including skeleton), and in the skeleton of young adult beagles. Retention was found to be dependent upon injection level, and different sets of equations were developed for dogs given about (a) 2.8 microCi/kg (b) 0.9 microCi/kg (c) 0.3 microCi/kg, and (d) 0.1 microCi/kg and less. Liver rention, RL, was characterized by a single exponential equation of the form RL = ce-beta t, with c = 0.49 +/- 0.04 and beta = a function of injection level. Nonliver tissue was assigned a retention equation of the form RNL = d + alpha + J(l - e-mt), with d = 0.102 +/- 0.024 e-1.22t, alpha = 0.41 +/- 0.04, and both J and m as a function of injection level. Skeletal retention was found to be about 0.885 +/- 0.037 of nonliver retention with no significant dependence upon either injection level or time after 241Am injection. Dosimetry equations based on these retention expressions were derived. Individual bones of 55 beagles were assayed at death for their 241Am content for a determination of 241Am distribution within the skeleton.     

Can mechanical forces be responsible for novel bone development and evolution in fishes?

Mechanical forces influence the induction, growth and maintenance of the vertebrate skeleton. Using the zebrafish, Danio rerio, we explore the hypothesis that mechanical forces can ultimately lead to the generation of skeletal evolutionary novelties by modifications of the mechano‐responsive molecular pathways. Locomotion and feeding in zebrafish larvae begin early in ontogeny and it is likely that forces incurred during these behaviours affect subsequent skeletal development. We provide two case studies in which our hypothesis is being tested: the kinethmoid and intermuscular bones. The kinethmoid is a synapomorphy for the order Cypriniformes and is intricately linked to the bones of the protrusible upper jaw. It undergoes chondrogenesis within a ligament well after muscular forces are present within the head. Subsequent ossification of the kinethmoid occurs at sites of ligamentous attachment, leading us to believe that mechanical forces are involved. Unlike the kinethmoid, which has evolved only once, intermuscular bones have evolved several times during teleostean evolution. Intermuscular bones are embedded within the myosepta, the collagenous sheets between axial muscles. The effect of mechanical forces on the development of these intermuscular bones is experimentally tested by increasing the viscosity of the water in which larval zebrafish are raised. Since locomotion in high viscosity requires greater muscular forces, we can directly test the influence of mechanical forces on the development of intermuscular bones. Using developmental techniques paired with outgroup comparison for the kinethmoid, and direct experimentation for intermuscular bones, our case studies provide complementary insights into the effects of mechanical forces on the evolution of skeletal novelties in fishes.     

Long-term distribution of 239-Pu, 241-Am,and 233-U in the various bones of the skeleton of adult rats

Conclusions The macrodistribution of the bone surface seekers plutonium and americium and of the bone volume seeker uranium has been analysed in different bones of the skeleton of adult male and female rats under identical laboratory conditions. Whereas the relative concentration differs in a wide range between the different bones and the different nuclides there is the general tendency with time to reach a mean concentration for the whole skeleton. Whereas the retention of 239-Pu and 241-Am is similar in the skeleton with a biological half-life of more than 1 year, 233-U shows a rapid decrease of the nuclide content with a biological half-life of 80 days in male and 140 days in female rats, respectively.     

Prediction of body weight of fossil Artiodactyla

Many dimensions of the postcranial skeleton of ruminant artiodactyls scale closely with body weight and are therefore potentially useful as predictors of body weight in fossil species. Using 45 dimensions of the skeleton a series of predictive equations was generated based on the scaling relationships of the family Bovidae. As a test of their usefulness these equations were used to predict body weights of a number of living ruminant artiodactyls, and six genera of fossil artiodactyls. For most species body weight estimates within 25° of actual weight were given by the mean of the predicted weights from all measurements except lengths of long bones. While femur length was a reasonable predictor of body weight, lengths of distal long bones were unreliable and should not be used as indicators of relative or absolute body weights. Some non-length measurements are biased in certain taxonomic groups; the possibility of erroneous estimates from such measurements can be reduced by using as many estimators of body weight as are available. No species of artiodactyl tested is so highly modified in all dimensions that all results were erroneous. Subsets of measurements which might be available from a typical fossil fragment also gave reliable results.     

The Shanidar 3 Neandertal

The Shanidar 3 Neandertal partial skeleton preserves four teeth, major portions of the thoracic and lumbar vertebrae, sacrum, ribs, clavicles, scapulae, humeri, hand bones, innominate bones, and foot bones, plus fragments of the ulnae, radii, femora, tibiae, and fibulae. Their morphology aligns Shanidar 3 closely with the other Shanidar Neandertals and the European and Near Eastern Neandertals. This is apparent especially in the dentition, scapulae, hand bones, and pubic bones.     

Scoring system for estimating age in the foot skeleton

This study assesses chronological age of immature individuals from the degree of ossification evident in the foot skeleton. We considered all tarsal and ray bones in various combinations to determine the most sensitive indicators of chronological age. Skeletal maturity was rated according to a subjective but simple scoring system applied to radiographs of normal feet of children of known chronological age. Scales for assessing the primary center of ossification, secondary center of ossification, and state of fusion are defined. In general, as expected, females show earlier onset of skeletal maturity than males; in particular, females in our sample are skeletally mature in most elements beginning 48 months prior to the earliest incidence of skeletal maturity in males for the same bones. Females in our sample show a marked tendency toward skeletal maturity of all elements by 150 months of age, while males do not show the same tendency until approximately 200 months of age. In general within each sex, consecutive states of fusion show broad overlap in range of chronological age within each bone. Combining scores from several different bones enables a reasonable estimate of potential age in a test application of the model.     

The density of long limb bones and the percentage ash weight of the skeleton of Macaca mulatta

The gravimetric density of humeri, radii, femora and tibiae from a series of 274 male and female skeletons of rhesus monkeys, Macaca mulatta, was determined for fetal, young and adult periods. The ages of 171 of the animals were known: they ranged from 57 days of gestation to 13.6 years; the ages of an additional 103 skeletons were estimated. The mean density of the fetal bones was found to increase linearly with age and was higher for males than females, and higher for the superior than for the inferior limb bones. During the young period the pattern of increase in density can be represented by a power-type curve, and the density is significantly higher in females than in males and in superior than in inferior limb bones. The densities of the long limb bones of the adult skeletons show a slight, but not significant, negative trend with increasing age. In this age group the mean densities are higher for males than females and higher for the superior than for the inferior limb bones. The percentage ash weight was determined for the total skeleton and for 21 subdivisions of 23 postnatal skeletons with estimated ages. The skull and long limb bones were found to have higher mean percentage ash weights than the vertebral segments and the sternum. Both the density and the percentage ash weight of the Macaca mulatta skeletons examined exceed those found in our earlier studies of the human skeleton.     

Evolutionary Consequences of Skeletal Differentiation

Some aspects of the differentiation, growth, and morphogenesisof the tissues within the skeleton are discussed and relatedto the evolution of the vertebrate skeleton. The tissues consideredare bone, cartilage, dentine, and enamel. The histology of the skeletal tissues of the Ordovician agnathais reviewed with the conclusion that the skeletal tissues ofthe first vertebrates were as diverse and as specialized asare those of present-day vertebrates. Phylogenies of skeletaltissues cannot be established. The trend during evolution appearsto have been toward reduction in amount of skeletal tissue andin the number of types of tissues present. The factors which determine when and where a skeletal elementdevelops ontogenetically are reviewed and used to discuss theorigin and evolution of jaws, the evolution of membrane bonesand the origin of such structures as sesamoid bones. Specialimportance is attached to epithelial-mesenchymal interactions. The factors which determine what particular skeletal tissuewill form at a particular site within the body are reviewedwith especial reference to modulation, germ layer derivation,and the role of epigenetic factors. The factors which determine size and shape of the skeleton,both ontogenetically and phylogenetically, are reviewed andthe directive role of adjacent tissues emphasized.     

Australia''s oldest human remains: age of the Lake Mungo 3 skeleton

We have carried out a comprehensive ESR and U-series dating study on the Lake Mungo 3 (LM3) human skeleton. The isotopic Th/U and Pa/U ratios indicate that some minor uranium mobilization may have occurred in the past. Taking such effects into account, the best age estimate for the human skeleton is obtained through the combination of U-series and ESR analyses yielding 62,000+/-6000 years. This age is in close agreement with OSL age estimates on the sediment into which the skeleton was buried of 61,000+/-2000 years. Furthermore, we obtained a U-series age of 81,000+/-21,000 years for the calcitic matrix that was precipitated on the bones after burial. All age results are considerably older than the previously assumed age of LM3 and demonstrate the necessity for directly dating hominid remains. We conclude that the Lake Mungo 3 burial documents the earliest known human presence on the Australian continent. The age implies that people who were skeletally within the range of the present Australian indigenous population colonized the continent during or before oxygen isotope stage 4 (57,000-71,000 years).     

Paralysis and growth of the musculoskeletal system in the embryonic chick

Avian embryos can be completely paralyzed by injection of neuromuscular-blocking agents. We used a single injection of decamethonium iodide to paralyze embryos at 7, 8, or 10 days of incubation and analyzed the growth of individual bones (clavicle, mandible, ulna, femur, tibia, humerus) and of individual muscles that act upon some of those bones (clavicular and sternal heads of m. pectoralis, and mm. biceps brachii, depressor mandibulae, pseudotemporalis, and adductor externus). Growth of the bones is not equally affected by paralysis. Only 27% of clavicular growth (by mass) but 77% of mandibular growth occurred in paralyzed embryos, whereas the four long bones exhibited 52-63% of their normal growth. Analysis of muscle weight, fiber length and physiological cross-sectional area (weight/fiber length) indicate that there was greater reduction of the muscles acting on the limbs than of those acting on the mandible, i.e., diminished growth of the skeleton is correlated with reduced muscular activity. Specific retardation of clavicular growth is due to fusion of sternal rudiments and collapse of the thorax, as well as virtual absence of the musculature that normally attaches to the clavicle. We discuss these results in the light of intrinsic and extrinsic factors governing growth of the embryonic skeleton. Paralysis reduces skeletal growth by reducing both the movements taking place in ovo, and the loads imposed on the bones by muscle contraction, changes that represent alterations in the mechanical environment of the skeleton.     

A developmental staging series for the African house snake, Boaedon (Lamprophis) fuliginosus

Embryonic staging series are important tools in the study of morphological evolution as they establish a common standard for future studies. In this study, we describe the in ovo embryological development of the African house snake (Boaedon fuliginosus), a non-venomous, egg-laying species within the superfamily Elapoidea. We develop our staging series based on external morphology of the embryo including the head, eye, facial prominences, pharyngeal slits, heart, scales, and endolymphatic ducts. An analysis of embryonic growth in length and mass is presented, as well as preliminary data on craniofacial skeletal development. Our results indicate that B. fuliginosus embryos are well into organogenesis but lack well-defined facial prominences at the time of oviposition. Mandibular and maxillary processes extend rostrally within 8 days (stage 3), corresponding to the first appearance of Meckel's cartilages. Overall, the development of the craniofacial skeleton in B. fuliginosus appears similar to that of other snake species with intramembraneous bones (e.g., dentary and compound bones) ossifying before most of the endochondral bones, the first of which to ossify are the quadrate and the otic capsule. Our staging series is the first to describe the post-ovipositional development of a non-venomous elapoid based on external morphology. This species is an extremely tractable captive that can produce large clutches of eggs every 45 days throughout the year. As such, B. fuliginosus should be a good model for evolutionary developmental biologists focusing on the craniofacial skeleton, loss of limbs, generational teeth, and venom delivery systems.