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1.
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.  相似文献   

2.
Even though many aspects of Dictyocha fibula and D. speculum have long been studied, very little is known about D. octonaria. For the first time a clonal culture derived from a single cell of D. octonaria from Wellington Harbour was studied in detail. In the skeleton‐bearing stage three morphotypes were observed – skeleton bearing, mucocyst‐bearing and amoeboid, while in the naked stage only the naked form was studied. In this study the mucocyst‐bearing form was described as a new morphotype. Vegetative reproduction of the skeleton‐bearing form in the exponential growth phase was by both direct binary fission and by first forming a doublet and then two separate daughter cells, while that of naked form was by simple binary fission. Occasionally double skeletons were observed as end products of both the vegetative and sexual reproductions. In sexual reproduction all three forms in the skeleton‐bearing stage exhibited the same polymorphic life history involving a multinucleate stage. The newly formed daughter cells of all three forms developed individual siliceous skeletons prior to being released from the parent cell. The naked form in the naked stage, however, exhibited a separate polymorphic life history that produced only skeleton‐free daughter cells. For the first time both vegetative and sexual reproduction of D. octonaria were documented.  相似文献   

3.
The investigation of the habitats, the spicular skeletons, and the structure and chemistry of the nonspicular high-Mg calcite skeletons of a fossil Acanthochaetetes from the Late Albian (Cretaceous) of Northern Spain and the extant Acanthochaetetes wellsi from Pacific reefs demonstrates an astonishing correspondence. The skeletons of both species are hemispherical or pyriform with the lower part containing an epitheca. They are built up of single calicles which are subdivided by tabulae. Spines protrude from the walls into the calicles. Scanning electron microscopy and thin sections reveal that the high-Mg calcite skeleton consists of two different microstructures: a irregular ssensu Wendt 1979 or microlamellar (sensu Cuif et al. 1979) and a completely irregular structure. AAS and EDAX analysis of the calcite skeletons produce roughly the same Mg and Sr contents. Tylostyle megascleres and aster-like microscleres are observed in the spicular skeletons of both species. The only difference between the two species is the greater variability of the microscleres in the extant species. Moreover, the fossil species incorporates the scleres in the non-spicular skeleton, while the extant species does not. Both species live/lived in the same niches of tropical reefs: the cryptic habitats of submarine caves in the reef core and the dimly lighted habitats of the deeper fore-reef.  相似文献   

4.
The new calcisponges Regispongia fluegeli n. sp., and Iranospongia circulara n. gen. n. sp., are described from central Iran. These are the first heteractinid sponges reported from the Permian of the region. These wewokellid sponges are large, irregularly cylindrical forms with a distinct axial spongocoel. The calcareous spicular skeletons of both taxa have been overgrown and are recrystallized. However, the preserved skeleton of Regispongia fluegeli does include large polyactines in the main endosomal layer and small octactines and possibly other polyactine spicules in both the relatively massive dermal layer and the distinct, delicately spiculed, gastral layer. Iranospongia is characterized by a discontinuous ring of vertical exhalant canals interior to the dense dermal layer, and by an interior skeleton net that includes common coarse vertical fibers. Individual spicules in Iranospongia are commonly obscured, but locally some remnants of possible polyactines occur in outer parts of the skeleton.  相似文献   

5.
A solitary articulated skeleton of a middle-aged and diseased Panthera leo spelaea lioness from the Eemian interglacial has been found amongst numerous articulated skeletons of Palaeoloxodon antiquus forest elephants, in sediments from a small, shallow lake at Neumark-Nord in central Germany, which has Neanderthal settlements along its shoreline. Several pathologies such as a fibula fracture, arthritis in one of the front legs and a lost canine tooth with associated maxillary inflammation and dissolution made the lioness vulnerable to other predators such as hyenas, whose presence is indicated by their bones, coprolites and many scavenging marks on the elephant skeletons and on a femur from a male lion. The scavenging of hyenas and lions at this site is commonly documented by canine bite marks on the joints of elephant bones. Bite and scratch marks on the ventral vertebral columns and pelvises of two P. antiquus forest elephant skeletons suggest that the intestines and inner organs may have been consumed by large predators, as is commonly the case with modern African lions feeding on elephants. The weak and diseased lioness may possibly have been killed during antagonistic battles between hyenas and lions over their larger prey.  相似文献   

6.
Summary— The membrane skeleton, responsible for shape and mechanical properties of the red cell, was purified by the Triton extraction procedure in presence of 5 mM, 150 mM or 600 mM NaCl. The proportion of spectrin, protein 4.1 and actin present in erythrocyte skeletons does not depend on the molarity of NaCl used. In contrast ankyrin, protein band 3 and protein 4.2 are removed from skeletons as the ionic strength increased. Solubilization assays of membrane skeletons were used to study protein interactions inside the skeleton. Solubilization was performed by Tris, a non-selective disruptive reagent, or by p-mercuribenzene sulfonic acid (PMBS), which principally release spectrin and actin. Tris action was assessed by calculation of the percentage of solubilized proteins, which increased proportionally with Tris molarity. PMBS action was kinetically determined as the decrease in skeleton turbidity. With these two reagents, we observed a lower dissociation of skeletons prepared with high ionic strength buffer. Erythrocyte pretreatment with okadaic acid, an inhibitor of serine-threonine phosphatases, revealed a phosphorylation-induced skeleton gelation and a better resistance to Tris-solubilization.  相似文献   

7.
Ossification sequences are poorly known for most amniotes, and yet they represent an important source of morphogenetic, phylogenetic, and life history information. Here, the author describes the ossification sequences of three ducks, the Common Eider Somateria mollissima dresseri, the Pekin Duck Anas platyrhynchos, and the Muscovy Duck Cairina moschata. Sequence differences exist both within and among these species, but are generally minor. The Common Eider has the most ossified skeleton prior to hatching, contrary to what is expected in a subarctic migrant species. This may be attributed to a tradeoff between growth rate and locomotory performance. Growth rate is higher in hatchlings with more cartilaginous skeletons, but this may compromise locomotion. No major ossification sequence differences were observed in the craniofacial skeleton when compared with Galliformes, which suggests that the influence of adult morphology on ossification sequence might be relatively minor in many taxa. Galliformes and Anseriformes, while both highly ossified at hatching, differ in the location of their late‐stage ossification centers. In Anseriformes, these are most often located in the appendicular skeleton, whereas in Galliformes they are in the thoracic region and form the ventilatory apparatus. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.  相似文献   

8.
The taxonomy of the siliceous members of Dictyochales has been based exclusively on the structure of their silica skeletons. In this study, other morphological, ultrastructural, pigment and molecular characters, in addition to the silica skeletons, were used in the systematics of the siliceous members of this group. As very little is known about the ultrastructure of Dictyocha octonaria, cells of both the skeleton‐bearing and naked forms were also studied. A cladistic analysis based on morphological data and a molecular phylogeny based on nuclear coded small subunit ribosomal DNA retrieved a well‐supported monophyletic Dictyochales. D. octonaria and D. speculum were resolved together with strong support. There was no support for a clade for the three species currently placed in Dictyocha; D. fibula is clearly distinct from the other two Dictyocha taxa, D. speculum and D. octonaria. It is highly likely there are two or three undescribed species within D. octonaria/D. speculum clade and two undescribed genera within the Dictyochales, based on the positions of sequences from uncultured eukaryotes present in GenBank. These findings necessitate a taxonomic revision of the three siliceous, skeleton‐bearing species. Because D. fibula is the type species of Dictyocha, we propose that D. octonaria and D. speculum be reassigned respectively to the genus Octactis as O. octonaria Hovasse and O. speculum (Ehrenberg) F. H. Chang, J. M. Grieve & J. E. Sutherland, comb. nov.  相似文献   

9.
Scleractinian corals begin their biomineralization process shortly after larval settlement with the formation of calcium carbonate (CaCO3) structures at the interface between the larval tissues and the substrate. The newly settled larvae exert variable degrees of control over this skeleton formation, providing an opportunity to study a range of biocarbonate structures, some of which are transient and not observed in adult coral skeletons. Here we present a morphological, structural, crystallographic, and chemical comparison between two types of aragonite deposits observed during the skeletal development of 2‐days old recruits of Pocillopora damicornis: (1) Primary septum and (2) Abundant, dumbbell‐like structures, quasi‐randomly distributed between initial deposits of the basal plate and not present in adult corals—At the mesoscale level, initial septa structures are formed by superimposed fan‐shaped fasciculi consisting of bundles of fibers, as also observed in adult corals. This organization is not observed in the dumbbell‐like structures. However, at the ultrastructural level there is great similarity between septa and dumbbell components. Both are composed of <100 nm granular units arranged into larger single‐crystal domains.Chemically, a small difference is observed between the septae with an average Mg/Ca ratio around 11 mmol/mol and the dumbbell‐like structures with ca. 7 mmol/mol; Sr/Ca ratios are similar in the two structures at around 8 mmol/mol—Overall, the observed differences in distribution, morphology, and chemistry between septa, which are highly conserved structures fundamental to the architecture of the skeleton, and the transient, dumbbell‐like structures, suggest that the latter might be formed through less controlled biomineralization processes. Our observations emphasize the inherent difficulties involved in distinguishing different biomineralization pathways based on ultrastructural and crystallographical observations. J. Morphol. 276:1146–1156, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   

10.
We describe an adult skeleton excavated in 1976 near Chéria, Algeria, in the context of a Capsian escargotière, associated with an absolute date of 9130 B.P. Analysis suggests a young adult male of moderate robustness and c. 181 cm in height. Comparison with published skeletal material from North Africa in Epipalaeolithic context concludes that the individual falls within the expected range of variation for this temporal period. The problem of assessing the affinity of individual skeletons is discussed.  相似文献   

11.
Slices cut from skeletons of massive Porites display two types of luminescence when illuminated by ultra-violet (UV) light: (1) faint luminescent banding associated with the annual skeletal density banding pattern and (2) narrow lines of strong luminescence associated with monsoonal runoff of fresh water from nearby land. Barnes and Taylor [Barnes, D.J. Taylor, R.B. 2001a. On the nature and causes of luminescent lines and bands in coral skeletons. Coral Reefs 19, 221-230] showed how larger skeletal holes could give rise to increased luminescence—thus accounting for the link between skeletal density banding and faint luminescent banding. Work described here tests the notion that strongly luminescent lines are also regions of lower skeletal density. Experiments involving real and artificial coral skeletons indicated that likely changes in hole size in real skeletons cannot account for the amount of luminescence associated with luminescent lines. Larger particles (< 50 μm) of powdered skeleton from cut from luminescent lines were more luminescent than similar particles cut from adjacent less luminescent skeleton. However, very small particles (< 3 μm) from the two regions of skeleton showed no difference in luminescence. Since skeletal crystals would have been largely destroyed by powdering skeleton to very small particle sizes, most of the luminescence of strongly luminescent lines is probably associated with changed crystal size and packing, with changed crystal chemistry, or with a combination of these possibilities.  相似文献   

12.
Within this paleodontological study 26 Achemenid and 8 Islamic skeletons from the excavations at Tahkt-i Suleiman (Western Iran) were investigated. The diagnosis of age and sex was done repeatedly according to various methods. The adult Achemenids reached an average age of 54.4 years (n = 16; SD = +/- 9.9 y), while the Islamic adult individuals reached a lifespan of 36.9 (n = 8; SD = +/- 11.0 y). The skeletons of the Achemenid children had an average of 6.8 years (n = 9; SD = +/- 3.3 y). In the specific dental investigations the teeth of all skeletons were checked for missing teeth or dental diseases or alterations of the jaws. For the whole series intravital loss of 19.3% of the teeth was found. 21.6% of the teeth were lost postmortally. The intravital loss of single teeth was 21.9% in the Achemenid teeth, disregarding the wisdom tooth and Dentes decidui; the respective value was 12% in the Islamic skeletons. The investigation for caries yielded a morbidity of 50% in the Achemenid skeletons, and 57% in the Islamic teeth. The frequency of caries was 6.2% in Achemenids and 9% in Islamic individuals. In the Dentes decidui the frequency of caries was found to be 3.6%. Dental tartar was present in 44.8% of the teeth, 42% of Achemenid teeth and 58% of Islamic teeth being affected. 33% of all teeth showed garlands of dental tartar. Signs of parodontolysis were investigated considering the health of the individual and the preservation of the skeleton. All adult teeth showed age-dependent parodontolysis, the means of which were quantified.  相似文献   

13.
四川自贡大山铺的劳氏灵龙   总被引:2,自引:1,他引:1  
本文对四川自贡大山铺的劳氏灵龙(Agilisaurus louderbacki)材料作了系统描述,并讨论了它的系统位置及与其它相关属种的关系.经比较:Yandusaurus multidens 应转归灵龙属中,成为灵龙的另一个种——多齿灵龙(Agilisaurus multidens);Xiaosaurus dashanpensis 可作为独立的属种.  相似文献   

14.
Summary The hygrochastic apparatus in Anastatica hierochuntica was investigated from the standpoint of morphology of the skeleton and fruit and its contribution to the regulation of seed dispersal in accordance with the water conditions.Water absorption by the dry skeletons upon shoot immersion under laboratory conditions is a rapid process requiring only a few minutes. It is followed by a slow opening of the curled branches of the skeleton. Maximal opening is attained by the saturated skeletons in approximately 2h. Absorption of water and subsequent opening occur also when only the main root of the skeleton is immersed in water. The process was duplicated also by intact skeletons irrigated in situ. Skeletons closure in response to evaporation is initially slow, noticable curling of the branches obtained only after 60% of the water is lost from the saturated skeletons. Opening of the skeleton exposes most of the fruits to the force of falling raindrops. The fact that no spontaneous opening of fruits occurred under most laboratory procedures of skeleton immersion suggests that in nature two successive processes occur: the skeletons must first uncurl-hygrochasticly so that raindrops can impinge forcefully on the appendages of the fruit valves and thus cause seed release by ombrohydrochory. Under adequate rainfall, the first fruits to open are those at the outer infructescences; heavier rainfall will release seeds from the upper fruits of the inner infructescences, and later, from fruits at their bases. The force that binds the valves of the fruits to the septa is variable, its strength correlated with different structure of the fruist at different positions on the skeleton. This ensures a rate of seed release commensurate with the rainfall, and secures at least a minimum of water for the first seeds. The heterogeneity of skeleton populations insofar as age of the plants is concerned, further ensures that seed dispersal in a given area will be proportional to the amount of rainfall.  相似文献   

15.
Abstract: The smallest living amniotes are all lizards, but the fossil history of this size trait in Squamata is difficult to follow because small skeletons have low preservation potential and are often hard to detect in the field. A new squamate taxon, Jucaraseps grandipes gen. et sp. nov., is here described on the basis of an articulated skeleton from the Early Cretaceous Spanish lagerstätten of Las Hoyas. It differs from other known Mesozoic lizards in combining very small body size with a short rostrum, low maxillary tooth count, a relatively slender and elongated body, and short limbs with large hind feet. Phylogenetic analysis using TNT places it on the stem of a clade encompassing scincomorphs, gekkotans, snakes, amphisbaenians and anguimorphs. Comparison with modern lizards suggests it was probably a cryptic surface or subsurface ground dweller but not a burrower.  相似文献   

16.
Hungarosaurus tormai is a medium-sized nodosaurid ankylosaur that was described on the basis of four partial skeletons from the Santonian (Upper Cretaceous) of Hungary. In this paper, a new fifth skeleton and several isolated remains are described which greatly improve our knowledge of this primitive nodosaurid ankylosaur. Isolated cranial remains referred to juvenile individuals provide new information on the development of cranial ornamentation in nodosaurid ankylosaurs. Apart from both preserved mandibles with in situ dentition, the fifth partial skeleton contains several previously unknown limb elements (humerus, ulnae, radius) that indicate unusual limb proportions for Hungarosaurus compared with other ankylosaurs. On the basis of the five partial skeletons and the isolated remains, a skeletal and dermal armor reconstruction is attempted. Body mass calculations using three different methods yield an estimate of 650 kg for H. tormai.   相似文献   

17.
Knowledge of skeletogenesis in scleractinian corals is central to reconstructing past ocean and climate histories, assessing and counteracting future climate and ocean acidification impacts upon coral reefs, and determining the taxonomy and evolutionary path of the Scleractinia. To better understand skeletogenesis and mineralogy in extant scleractinian corals, we have investigated the nature of the initial calcium carbonate skeleton deposited by newly settling coral recruits. Settling Acropora millepora larvae were sampled daily for 10 days from initial attachment, and the carbonate mineralogy of their newly deposited skeletons was investigated. Bulk analyses using Raman and infrared spectroscopic methods revealed that the skeletons were predominantly comprised of aragonite, with no evidence of calcite or an amorphous precursor phase, although presence of the latter cannot be discounted. Sensitive selected area electron diffraction analyses of sub-micron areas of skeletal regions further consolidated these data. These findings help to address the uncertainty surrounding reported differences in carbonate mineralogy between larval and adult extant coral skeletons by indicating that skeletons of new coral recruits share the same aragonitic mineralogy as those of their mature counterparts. In this respect, we can expect that skeletogenesis in both larval and mature growth stages of scleractinian corals will be similarly affected by ocean acidification and predicted environmental changes.  相似文献   

18.
Fully adult partial skeletons attributed to Australopithecus afarensis (AL 288-1, “Lucy”) and to Homo habilis (OH 62, “Lucy's child”), respectively, both include remains from upper and lower limbs. Relationships between various limb bone dimensions of these skeletons are compared to those of modern African apes and humans. Surprisingly, it emerges that OH 62 displays closer similarities to African apes than does AL 288-1. Yet A. afarensis, whose skeleton is dated more than 1 million years earlier, is commonly supposed to be the ancestor of Homo habilis. If OH 62, classified as Homo habilis by its discoverers, does indeed represent a stage intermediate between A. afarensis and later Homo, a revised interpretation of the course of human evolution would be necessary.  相似文献   

19.
The discovery of a Middle Epipaleolithic adult skeleton (F-81) at the site of Wadi Mataha in southern Jordan provides new insights into human variability in the Epipaleolithic of the Levant. This paper analyzes the skeletal morphology of Wadi Mataha F-81 in the context of other Epipaleolithic remains from Jordan and Israel to assess the current evidence for morphological variability throughout this period. The F-81 skeleton shares morphological features with earlier Epipaleolithic skeletons from Ohalo and Nahal Ein Gev, and later Natufian populations. Despite the morphological similarities, F-81 extends the range of known variability prior to the Natufian with its unusually small stature and unique combination of morphological characteristics. High levels of cranial and postcranial robusticity suggest that the F-81 individual was physically active and terrestrially mobile. Pronounced bilateral asymmetry in the upper limb suggests significant lateralization of habitual activity. In the context of Epipaleolithic remains, the F-81 skeleton provides preliminary evidence for greater morphological variability, terrestrial mobility, and lateralized habitual behavior prior to the Natufian, and skeletal gracilization between the Middle and Late Epipaleolithic in the Levant.  相似文献   

20.

Background

Protocetidae are middle Eocene (49–37 Ma) archaeocete predators ancestral to later whales. They are found in marine sedimentary rocks, but retain four legs and were not yet fully aquatic. Protocetids have been interpreted as amphibious, feeding in the sea but returning to land to rest.

Methodology/Principal Findings

Two adult skeletons of a new 2.6 meter long protocetid, Maiacetus inuus, are described from the early middle Eocene Habib Rahi Formation of Pakistan. M. inuus differs from contemporary archaic whales in having a fused mandibular symphysis, distinctive astragalus bones in the ankle, and a less hind-limb dominated postcranial skeleton. One adult skeleton is female and bears the skull and partial skeleton of a single large near-term fetus. The fetal skeleton is positioned for head-first delivery, which typifies land mammals but not extant whales, evidence that birth took place on land. The fetal skeleton has permanent first molars well mineralized, which indicates precocial development at birth. Precocial development, with attendant size and mobility, were as critical for survival of a neonate at the land-sea interface in the Eocene as they are today. The second adult skeleton is the most complete known for a protocetid. The vertebral column, preserved in articulation, has 7 cervicals, 13 thoracics, 6 lumbars, 4 sacrals, and 21 caudals. All four limbs are preserved with hands and feet. This adult is 12% larger in linear dimensions than the female skeleton, on average, has canine teeth that are 20% larger, and is interpreted as male. Moderate sexual dimorphism indicates limited male-male competition during breeding, which in turn suggests little aggregation of food or shelter in the environment inhabited by protocetids.

Conclusions/Significance

Discovery of a near-term fetus positioned for head-first delivery provides important evidence that early protocetid whales gave birth on land. This is consistent with skeletal morphology enabling Maiacetus to support its weight on land and corroborates previous ideas that protocetids were amphibious. Specimens this complete are virtual ‘Rosetta stones’ providing insight into functional capabilities and life history of extinct animals that cannot be gained any other way.  相似文献   

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