Skeletal Elements Research Articles

NOT ENTIRELY ICHTHYOSAUR: A MYSTERIOUS LAMNIFORM AND ICHTHYOPTERYGIAN-FALL ASSOCIATION FROM THE ABYSSAL UPPER CRETACEOUS OF THE NORTHERN APENNINES (ITALY)

ABSTRACT Axial remains of a large ichthyosaur and a medium-sized anacoracid shark from the deep-water sediments of the Cenomanian of the Northern Apennines (Northern Italy) are described in detail. The specimens were found closely associated (less than 0.3 m apart), and offer an invaluable window into the taphonomy and dead-fall stages of pelagic vertebrates in a Mesozoic abyssal plain. The anacoracid shark remains, initially misinterpreted as an ichthyosaur, consist of eight articulated vertebrae embedded in a block of dark arenaceous matrix, and represent the first occurrence of an articulated shark from the Northern Apennines. The ichthyosaur remains consist of seven discoidal vertebrae and several unidentified fragments. Due to the absence of diagnostic skeletal elements, both specimens are assigned only at higher taxonomic levels. The two fossils, which come from the same outcrop and possibly from the same stratigraphic horizon, share a common taphonomic history, in terms of both their preservation and diagenesis. Mineralogy of the matrices of both is dominated by manganese micro-nodules, consistent with the deposition of polymetallic nodules in bathyal-abyssal settings. Biostratinomic processes that impacted the two specimens also provide insight on the development of Mesozoic marine vertebrate-falls in the deep-sea. Localized pyrite framboids inside the bone spongiosa are possible evidence of the sulfophilic stage (microbially mediated sulfur mobilization during lipid decay) in the ichthyosaur fall. Burrows assigned to Taenidium on the surface of the shark block, interpreted as worm-like feeding burrows or arthropod locomotion and feeding trails, might represent evidence of the enrichment opportunistic stage. Although intriguing, we have no evidence to support the hypothesis that this peculiar association of two pelagic predators is due to ecological interaction between the two animals.

A surrogate forelimb: Evolution, function and development of the avian cervical spine.

The neck is a critical portion of the avian spine, one that works in tandem with the beak to act as a surrogate forelimb and allows birds to manipulate their surroundings despite the lack of a grasping capable hand. Birds display an incredible amount of diversity in neck morphology across multiple anatomical scales-from varying cervical counts down to intricate adaptations of individual vertebrae. Despite this morphofunctional disparity, little is known about the drivers of this enormous variation, nor how neck evolution has shaped avian macroevolution. To promote interest in this system, I review the development, function and evolution of the avian cervical spine. The musculoskeletal anatomy, basic kinematics and development of the avian neck are all documented, but focus primarily upon commercially available taxa. In addition, recent work has quantified the drivers of extant morphological variation across the avian neck, as well as patterns of integration between the neck and other skeletal elements. However, the evolutionary history of the avian cervical spine, and its contribution to the diversification and success of modern birds is currently unknown. Future work should aim to broaden our understanding of the cervical anatomy, development and kinematics to include a more diverse selection of extant birds, while also considering the macroevolutionary drivers and consequences of this important section of the avian spine.

Predictive use of modern reference osteological collections for disentangling the shape of Eurasian equid cheek teeth and metapodials in archaeological material

AbstractEquids have shaped past Eurasian societies in many ways. This applies in particular to domestic horses, donkeys, and their hybrids. Key to documenting modes of exploitation and cultural trajectories in past societies is the correct taxonomic classification of tooth and bone specimens found in archaeological sites. However, close osteomorphological resemblance of wild and domestic equids and their economically valuable hybrids, that is, mules and hinnies, complicates the identification of intentionally fragmented or naturally damaged archaeological specimens. Here, we apply geometric morphometrics (GM) to mandibular teeth and metapodials, two skeletal elements commonly found in archaeological collections and known for their diagnostic properties using traditional morphometric methods. We registered a statistically representative set of 2D and 3D coordinates on mandibular teeth (P3, P4, M1, and M2) and metapodials of 92 domestic horses (Equus caballus Linnaeus, 1758), 70 domestic donkeys (Equus asinus Linnaeus, 1758), 30 hybrids, and 63 Asiatic wild asses (Equus hemionus Pallas, 1775). Taxonomic classification of these 255 specimens considered both shape and form, applying linear discriminant analysis, k‐nearest neighbors algorithm, and artificial neural networks to seven combinations of taxa. We obtained correct classifications in over 87% and 80%, respectively, of the premolars and molars and in over 93% and 89%, respectively, of the metacarpals and metatarsals. This modern dataset was then used to classify equid specimens from three archaeological sites in the Middle East already analyzed morphologically. Taking into account the past zoogeography of wild equids and the historical distribution of their domesticated descendants and hybrids, the GM approach presented in this study offers the possibility to morphologically classify archaeological equids with far greater certainty than has been the case so far.

First record of abelisaurid theropods and a peirosaurid crocodyliform from the Upper Cretaceous of Precordillera of La Rioja, NW Argentina

Extra-Patagonian records of Cretaceous theropod dinosaurs in Argentina are limited. When it comes to the Northwest of Argentina, most of the records come from the Cretaceous rocks of Salta Province, which yielded ceratosaurian abelisauroids like Noasaurus and Guemesia. Preliminary studies of the Los Llanos Formation at Eastern La Rioja Province recognized bone remains of Upper Cretaceous undetermined Abelisauridae and Coelurosauria. Recent surveys in the Northwest of the same province, in the outcrops of the Upper Cretaceous Ciénaga del Río Huaco Formation, at Quebrada Santo Domingo (Precordillera), resulted in the discovery of six isolated shed tooth crowns of putative abelisaurid theropods and crocodyliforms. They were found in association with partial skeletons of titanosaurid sauropod dinosaurs from two quarry sites, in the lower and upper sections of the same unit. Here we corroborate the taxonomic assignment of these specimens and their phylogenetic relationships. Five out of six teeth were assigned to Abelisauridae, whereas the remaining is considered to belong to a peirosaurid crocodyliform. Thus, the first occurrence of abelisaurid theropods and peirosaurid crocodyliforms in the Upper Cretaceous of the Precordillera of La Rioja is confirmed. Even though the teeth cannot be assigned to a less inclusive taxon, the difference in their stratigraphic position might indicate the presence of more than a single abelisaurid species in this region. The new results offer an optimistic perspective for future expeditions in this area, which intend to recover more skeletal elements.

A two-galectin network establishes mesenchymal condensation phenotype in limb development

Previous work showed that Gal-1A and Gal-8, two proteins belonging to the galactoside-binding galectin family, are the earliest determinants of the patterning of the skeletal elements of embryonic chicken limbs, and further, that their experimentally determined interactions in the embryonic limb bud can be interpreted via a reaction–diffusion–adhesion (2GL: two galectin plus ligands) model. Here, we use an ordinary differential equation-based approach to analyze the intrinsic switching modality of the 2GL network and characterize the network behavior independent of the diffusive and adhesive arms of the patterning mechanism. We identify two states: where the concentrations of both the galectins are respectively, negligible, and very high. This bistable switch-like system arises via a saddle–node bifurcation from a monostable state. For the case of mass-action production terms, we provide an explicit Lyapunov function for the system, which shows that it has no periodic solutions. Our model therefore predicts that the galectin network may exist in low expression and high expression states separated in space or time, without any intermediate states. We test these predictions in experiments performed with high density cultures of chick limb mesenchymal cells and observe that cells inside precartilage protocondensations express Gal-1A at a much higher rate than those outside, for which it was negligible. The Gal-1A and -8-based patterning network is therefore sufficient to partition the mesenchymal cell population into two discrete cell states with different developmental (chondrogenic vs. non-chondrogenic) fates. When incorporated into an adhesion and diffusion-enabled framework this system can generate a spatially patterned limb skeleton.

Sex and ancestry estimation in South Africans from measurements of the calcaneus and talus - a validation study.

Forensic anthropological methodology needs to continuously be tested and validated to remain on par with international standards of best practice. The present study aimed to validate previously published metric and non-metric methods for estimating sex and population affinity from the calcaneus and talus in black and white South Africans. The calcanei and tali of two-hundred individuals, equally distributed by sex and population, were measured and the validity of the discriminant functions were assessed. Only some functions estimating sex using both skeletal elements and estimating population affinity using the calcaneus are valid, with present and original accuracies not differing significantly (p > 0.05). Population affinity estimation functions using the talus, however, are not valid. Functions yielding accuracies in the present study between 50.00% and 74.00% should not be used as these rates are only slightly above chance (50.00%), but functions yielding accuracies of 75.00% and above may be considered for use in forensic casework. Almost all functions yielded accuracies significantly lower (p < 0.05) for females and for black individuals compared to their male and white counterparts, respectively. As a result, the classification of individuals as female or as black should particularly be interpreted with caution. This study also assessed the validity of previously described morphological methods used to estimate population affinity using the calcaneus. The number of talar articular facets present differs significantly between population groups and the validity of this method was therefore confirmed. These methods should be further validated using more modern skeletal collections or living individuals using various virtual methodologies.

Sr/Ca-temperature calibration for the coral Montastraea cavernosa

The Sr/Ca ratio in coral skeletons is an important proxy for the reconstruction of sea surface temperatures (SST) of the environment and helps our knowledge about SST variability in the tropics. In the western tropical South Atlantic where the species Montastraea cavernosa is one of the most important reef-builders, only a few species have been evaluated as coral-based archives for environmental changes. Here we evaluate the Sr/Ca ratio recorded in the thecal wall and other skeletal structures of the species M. cavernosa and its implications for paleothermometry investigations. Sampling along the thecal wall generated a record of Sr/Ca ratios with well-defined annual cycles, but also with noisy intervals. A linear regression of the most recent 8 years of well-defined Sr/Ca ratios and SST results in the calibration equation Sr/Ca (mmol/mol) = −0.040 (±0.005) * SST (°C) + 10.15 (±0.15). This is the first calibration equation for this species. The skeletal elements of M. cavernosa were characterized by heterogeneous Sr/Ca ratios, with higher values for the columellae and septum, which could potentially generate a cold bias in reconstructed SST of up to 7.5 °C. The variability of Sr/Ca ratios in these structures overwhelms the annual seasonality of Sr/Ca ratios in the thecal wall, and the difference in Sr/Ca ratios observed from distinct skeletal structures may be related to biological or vital effects influencing the uptake of Sr into different coral structures. Furthermore, improving sampling techniques for M. cavernosa should be considered in future studies for the successful recovery of robust geochemical signals, eventually expanding the number of species used as natural archives in the western tropical South Atlantic.

Commitment of human mesenchymal stromal cells to skeletal lineages is independent of their morphogenetic capacity.

Mesenchymal stromal cells (MSCs) are multipotent cell populations obtained from fetal and adult tissues. They share some characteristics with limb bud mesodermal cells such as differentiation potential into osteogenic, chondrogenic, and tenogenic lineages and an embryonic mesodermal origin. Although MSCs differentiate into skeletal-related lineages in vitro, they have not been shown to self-organize into complex skeletal structures or connective tissues, as in the limb. In this work, we demonstrate that the expression of molecular markers to commit MSCs to skeletal lineages is not sufficient to generate skeletal elements in vivo. To evaluate the potential of MSCs to differentiate into skeletal lineages and generate complex skeletal structures using the recombinant limb (RL) system. We used the experimental system of RLs from dissociated-reaggregated human placenta (PL) and umbilical cord blood (UCB) MSCs. After being harvested and reaggregated in a pellet, cultured cells were introduced into an ectodermal cover obtained from an early chicken limb bud. Next, this filled ectoderm was grafted into the back of a donor chick embryo. Under these conditions, the cells received and responded to the ectoderm's embryonic signals in a spatiotemporal manner to differentiate and pattern into skeletal elements. Their response to differentiation and morphogenetic signals was evaluated by quantitative polymerase chain reaction, histology, immunofluorescence, scanning electron microscopy, and in situ hybridization. We found that human PL-MSCs and UCB-MSCs constituting the RLs expressed chondrogenic, osteogenic, and tenogenic molecular markers while differentially committing into limb lineages but could not generate complex structures in vivo. MSCs-RL from PL or UCB were committed early to chondrogenic lineage. Nevertheless, the UCB-RL osteogenic commitment was favored, although preferentially to a tenogenic cell fate. These findings suggest that the commitment of MSCs to differentiate into skeletal lineages differs according to the source and is independent of their capacity to generate skeletal elements or connective tissue in vivo. Our results suggest that the failure to form skeletal structures may be due to the intrinsic characteristics of MSCs. Thus, it is necessary to thoroughly evaluate the biological aspects of MSCs and how they respond to morphogenetic signals in an in vivo context. PL-MSCs and UCB-MSCs express molecular markers of differentiation into skeletal lineages, but they are not sufficient to generate complex skeletal structures in vivo.

Histotaphonomy of a Pleistocene megamammal assemblage from Argentine Pampas

This work involves a multy-proxy approach of taphonomic features of the extinct giant ground sloth Lestodon armatus (Xenarthra, Mylodontidae). The study is based on paleohistological, mineralogical, and geochemical analyses from the Late Pleistocene Playa del Barco site (Buenos Aires Province, Argentina). Transverse thin sections of ribs and vertebrae were studied under light microscope, polarizing petrographic microscope, and scanning electron microscope (SEM), combined with chemical analysis using energy dispersive spectroscopy (EDS) and micro-X-ray diffraction (μXRD). The internal crystalline structure and mineral composition remains almost unaltered. The bone microstructure is well preserved in all the samples, although it was affected by different types of microfractures and infillings. Numerous radial microcracks were identified in the secondary osteons of all specimens evidencing wet depositional environment. The mineralogical and geochemical composition of the infillings and encrustations indicates that the enrichment with new elements was due to direct exchange with the sediments in which they were buried. Mineralogical evidence from the infillings allows to identify different diagenetic pathways; most of the skeletal elements were quickly buried in the vadose zone, while others were buried in the phreatic zone, directly or after some time immersed in a continental aquatic context. The fossildiagenetic information obtained from the Lestodon armatus fossils provides novel information to interpret and reconstruct the whole taphonomic history and the environmental and climatic conditions that favored the preservation of the Playa del Barco fossil assemblage during the end of the Last Glacial Maximum.

Structural integrity and skeletal trace elements in intertidal coralline algae across the Northeast Atlantic reveal a distinct separation of the leading and the trailing edge populations

Intertidal macroalgae, such as coralline algae, represent an essential structural element and substrate in rocky coastal zones. They have a high degree of flexibility allowing their survival in environments with severe mechanical stress during tidal cycles. This study characterised the genicula and intergenicula of the calcifying red algae Corallina officinalis across its geographic distribution in the Northeast Atlantic. Poleward populations have constructed more sturdy cell walls compared to equatorward populations, potentially due to greater local adaptations to higher frequency and intensity of environmental factors like storms and wave action. Southern populations showed a lack of local adaptation culminating in survival rather than thriving within their current environment, hence, they are located at the margin of this species' favourable conditions. Results clarify significant differences between latitudes and indicate a north-to-south gradient in this species’ skeletal elemental composition. Northern populations were dominated by cadmium, whereas chromium was the major trace element found in southern populations. In the future, these characteristics could lead to a permanent decline and a decrease in the ecosystem functions of C. officinalis in the southern locations in the Northeast Atlantic, which may be accelerated by predicted future climatic changes.

Intrageneric taxonomic distinction based on morphological variation in the macaque (Macaca) skeleton.

Taxonomic classification is important for understanding the natural world, yet current methods for species assessment often focus on craniodental morphology rather than the entire skeleton. Moreover, it is currently unknown how much variation could, or should, exist intragenerically. Here, we tested whether taxonomy can be accurately predicted based on patterns of morphological variation in macaques (H1 ) and whether postcranial bones reflect subgeneric macaque taxonomy similarly, or better, than the cranium (H2 ). Data included 3D scans of cranial and postcranial bones for eight macaque species (Macaca arctoides, Macaca fascicularis, Macaca fuscata, Macaca mulatta, Macaca nemestrina, Macaca nigra, Macaca radiata, and Macaca sylvanus). Fixed anatomical and semilandmarks were applied to scans of eight skeletal elements (crania = 45; mandible = 31; scapula = 66; humerus = 38; radius = 33; os coxa = 28; femur = 40; tibia = 40). For each skeletal element, regression analyses were performed to minimize the effects of sexual dimorphism. Between-groups principal components analysis was used to visualize the major patterns of among-species morphological variation, while the strength of correct taxon classification was measured with discriminant function analysis. Results suggested accepting the alternate hypothesis that different macaque species can be distinguished morphologically. Both cranial and many postcranial elements appeared to possess a taxonomic signal, and the limb bones-especially the upper limb-are reported to be more useful for taxonomic assessment than previously realized. Theoretically, certain behaviors and/or ecogeographical factors, as well as phylogeny, influenced skeletal morphology in macaques, likely contributing to taxonomic distinctions among different species.

Age estimation biases based on body size: the differential impacts of soft tissue on skeletal ageing

AbstractThe aim of this research project is to explore the differential impacts of soft tissues on skeletal ageing and apply these findings to skeletal age estimation methods. Computed tomography (CT) scans of 412 size‐selected individuals from Ontario, Canada, were assessed using an adapted pubic symphysis age estimation method. Individuals ranged from 20 to 79 years of age (mean = 49.46 years), with 208 males and 204 females. Almost 80 per cent of the sample was assigned to the correct age phase; those not correctly aged followed a similar pattern. Individuals with higher body mass, body mass index (BMI), circumference, and total fat area were over‐aged and those with lower body mass, BMI, circumference, and total fat area were under‐aged. High amounts of adipose tissue led to increased skeletal degeneration, but high amounts of muscle tissue did not have a protective effect. Skeletal elements were not reliable proxies for body mass; however, other morphological features may help identify individuals with high body mass from skeletal remains.

Estimation of Gender and Age Based on Three-dimensional Computed Tomography Scan Indices of the Twelfth Thoracic Vertebrae and the First and Fifth Lumbar Vertebrae in Iranian Adults

Background: Gender identification is a crucial starting point in creating a biological profile for human skeletal remains because it reduces the number of possible matches by 50%. The vertebrae (especially the chest and back) can also be some of the best-preserved skeletal elements in some areas of forensics and archeology. In the present study, gender and age were assessed based on the measurement of three-dimensional computed tomography (CT) scan indices of the Twelfth thoracic (T12) vertebrae and the first and fifth lumbar (L1 and L5) vertebrae in Iranian adults. Methods: The present study was a descriptive study carried out on 200 participants over 18 years of age in 2020. Individuals measuring thoracic and lumbar vertebrae diameters (T12 and first and fifth lumbar vertebrae) by three-dimensional computed tomography (CT) scan (Toshiba, Japan, 16-Slice) with multiplanar reconstruction (MPR) and volume rendering were placed in two sagittal and horizontal sections. Results: The mean age of male and female participants was 34.62±9.63 years and 34.10±9.70 years, respectively, which were not significantly different (P=0.789). The present study showed that the mean indices for T12, L1 and L5 vertebrae were significantly higher in males (P&gt;0.05). The results also showed that T12, L1, and L5 indices of nuts are not good predictors for age estimation. Conclusion: Based on the results, the indices of the T12 vertebrae and the L1, and L5 vertebrae can be used to determine gender, but these indices are not a good criterion to estimate age and do not have the necessary accuracy to predict the age variable.

GAME BIRDS IN THE ECONOMY OF THE POPULATION OF BEREZOV (BASED ON THE RESULTS OF ARCHAEOZOOLOGICAL ANALYSIS)

Based on the evidence from osteological collection of birds (over 7,000 specimens), the hunting of game by the population of the town of Berezov in Modern period was reconstructed. The study identified species composition of game birds and conducted an analysis of the ratio of skeletal elements, fragmentation of bones, and external influences. The main purpose of bird hunting was to obtain an additional source of meat for the population of the town. Over time, the relative significance of poultry in the diet of the urban population decreased, but the intensity of game hunting remained constantly high. The game was hunted all year round. Spring-summer hunting for waterfowl was a dominant type. In winter, they hunted mainly for wood grouse and ptarmigan. Based on the average weight of each species, the authors calculated the potential amount of meat that can be obtained from the hunting for the three main groups of birds. It is shown that in the cold season, the supply of additional meat products from bird hunting decreased almost threefold compared with the spring-summer time.

Coral Sr‐U Thermometry Tracks Ocean Temperature and Reconciles Sr/Ca Discrepancies Caused by Rayleigh Fractionation

AbstractUnderstanding climate change at the spatiotemporal scales necessary to improve climate projections requires proxy records that complement sparse and often contradictory observational temperature data sets. Massive long‐lived corals have tremendous potential in this regard, continuously recording information about ocean conditions as they grow. Nevertheless, extracting accurate ocean temperatures from corals is challenging because factors other than temperature influence skeletal chemistry. Here, we tested the ability of the coral Sr‐U thermometer to accurately capture annual sea surface temperatures (SSTs) in the subtropical Atlantic, where year‐to‐year temperatures vary by ∼1°C. Using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS), we generated sufficient U/Ca – Sr/Ca pairs from a slow‐growing (1−2 mm/yr) Siderastrea siderea coral to calculate annual Sr‐U values. With the fine‐scale spatial resolution attained using the laser, skeleton accreted during both fast and slow growing times of the year was represented in our sampling. The resulting 30‐year‐long Sr‐U record tracked the amplitude and timing of annual SST to within ±0.2°C of observations (r = −0.71), whereas the Sr/Ca record did not (r = 0.23). Furthermore, Sr‐U corrected for Sr/Ca offsets among adjacent skeletal elements approximately 1 mm apart. These offsets are equivalent to differences of 2–3°C if typical Sr/Ca–SST calibrations are applied. Our observations indicate that Sr‐U can accurately constrain decadal‐to‐multidecadal variability and secular SST trends in regions where this information is urgently needed.

Osteological material and the population state of the speckled ground squirrel (Spermophilus suslicus) on the periphery of the species’ distribution (Belarus)

The studies were carried out in 2021 near the village of Yushevichi, Nesvizh Raion, Minsk Oblast (Belarus). The content of pellets of three bird species were analysed: Buteo buteo, Buteo lagopus, and Corvus corax. In total, 129 intact and about 30 destructed pellets were processed. Skeletal elements of five small mammal species belonging to five genera of two orders (Rodentia and Eulipotyphla) were found, including remains of nine speckled ground squirrels. The remains of seven of the nine ground squirrel individuals found in the pellets were found in raven pellets, however, the authors believe that this fact does not yet prove a greater influence of the raven on the local ground squirrel population. The pellets analysis and observations of feeding behaviour of the three bird species prove that the speckled ground squirrel is constantly included in the diet of both diurnal birds of prey (genus Buteo) and of atypical predators with a mixed nutrition (raven). Finding of intact skulls of Spermophilus suslicus in pellets of the mentioned bird species is unlikely, which is determined by its considerable size. This circumstance does not allow obtaining most of the craniometric characters, but does not prevent the detection of pathomorphological changes. To compare the craniological characters, we used the skulls of dead ground squirrels (n = 5) found in the field near the village of Yushevichi. These individuals had visible injuries (lacerated wounds, etc.) presumably left both by predators and fights between ground squirrels. The most striking pathomorphological changes were revealed: osteoporosis and osteolysis of dental alveoli of the upper and lower jaws and initial osteomyelitis of the cranial vault (in the parietal and frontal bones). We believe that the speckled ground squirrel’s conservation status should be raised to at least Category II (according to the system of categories adopted in Belarus) for the following reasons: over the past six years, out of 12 known colonies, only four colonies have survived, two of which are practically unviable; stable for 10 years reduction in the number; and range fragmentation (single localities). According to the IUCN classification, it corresponds to category CR (critically endangered).

Embryonic development of the pelvic girdle and hindlimb skeletal elements in Anilius scytale (Linnaeus,1758) (Serpentes: Aniliidae).

Anilius scytale is the sister lineage of all other alethinophidian snakes. Morphology of the hind limb complex in adult A. scytale (Aniliidae) has been documented. We herein, for the first time, describe the embryology of the skeletal elements of its hind limb and pelvic girdle and contextualize the evolution of these structures. We identified pregnant females of A. scytale in the Herpetology Collection of the Museu Paraense Emílio Goeldi and separated 40 embryos. The embryos were sequentially staged using external and internal anatomy, collectively comprising a developmental series representing six stages. We cleared-stained one specimen of stages 31, 34, 36, and 37. Using the embryological information gleaned from A. scytale, we reinterpret evidence relating to the ossification of the pelvis and hindlimbs. In A. scytale hindlimb buds develop as transient structures that developed before Stage 30 and regresses in subsequent stages. There is no external or internal evidence of the forelimb or scapular girdle. From Stage 31 onwards the ischium, pubis, ilium, femur and zeugopodial cartilages are visible. Pubis and femur ossify towards the end of embryonic life, and cloacal spurs do not develop in the embryo. Skeletal elements of the hindlimb and pelvic girdle develop initially in the ventral zone of the cloaca-tail region. In subsequent stages the hindlimb and pelvic girdle elements migrate dorsally, with the pubis/ischium positioned medial to the ribs. A similar process may be associated with the achievement of the condition of the pelvic girdle in adults of scolecophidians, pythonids and boids.

Biological light-weight materials: The endoskeletons of cephalopod mollusks

Structural biological hard tissues fulfill diverse tasks: protection, defence, locomotion, structural support, reinforcement, buoyancy. The cephalopod mollusk Spirula spirula has a planspiral, endogastrically coiled, chambered, endoskeleton consisting of the main elements: shell-wall, septum, adapical-ridge, siphuncular-tube. The cephalopod mollusk Sepia officinalis has an oval, flattened, layered-cellular endoskeleton, formed of the main elements: dorsal-shield, wall/pillar, septum, siphuncular-zone. Both endoskeletons are light-weight buoyancy devices that enable transit through marine environments: vertical (S. spirula), horizontal (S. officinalis). Each skeletal element of the phragmocones has a specific morphology, component structure and organization. The conjunction of the different structural and compositional characteristics renders the evolved nature of the endoskeletons and facilitates for Spirula frequent migration from deep to shallow water and for Sepia coverage over large horizontal distances, without damage of the buoyancy device.Based on Electron-Backscatter-Diffraction (EBSD) measurements and TEM, FE-SEM, laser-confocal-microscopy imaging we highlight for each skeletal element of the endoskeleton its specific mineral/biopolymer hybrid nature and constituent arrangement. We demonstrate that a variety of crystal morphologies and biopolymer assemblies are needed for enabling the endoskeleton to act as a buoyancy device. We show that all organic components of the endoskeletons have the structure of cholesteric-liquid-crystals and indicate which feature of the skeletal element yields the necessary mechanical property to enable the endoskeleton to fulfill its function. We juxtapose structural, microstructural, texture characteristics and benefits of coiled and planar endoskeletons and discuss how morphometry tunes structural biomaterial function. Both mollusks use their endoskeleton for buoyancy regulation, live and move, however, in distinct marine environments.

Age-Related Changes in Post-Translational Modifications of Proteins from Whole Male and Female Skeletal Elements.

One of the key questions in forensic cases relates to some form of age inference, whether this is how old a crime scene is, when in time a particular crime was committed, or how old the victim was at the time of the crime. These age-related estimations are currently achieved through morphological methods with varying degrees of accuracy. As a result, biomolecular approaches are considered of great interest, with the relative abundances of several protein markers already recognized for their potential forensic significance; however, one of the greatest advantages of proteomic investigations over genomics ones is the wide range of post-translational modifications (PTMs) that make for a complex but highly dynamic resource of information. Here, we explore the abundance of several PTMs including the glycosylation, deamidation, and oxidation of several key proteins (collagen, fetuin A, biglycan, serum albumin, fibronectin and osteopontin) as being of potential value to the development of an age estimation tool worthy of further evaluation in forensic contexts. We find that glycosylations lowered into adulthood but deamidation and oxidation increased in the same age range.

Craniogenetic studies in Sus scrofa: With emphasis on the 'orbitosphenoid' problem.

The orbitosphenoid is a skeletal element of the endocranium of extant mammals. However, it has also been described in many of their fossil ancestors. Craniogenetic studies show that it is composed of two types of bone: first, the cartilaginous ala orbitalis and parts of the trabecular plate are transformed by endochondral ossification; second, so-called 'appositional bone' ('Zuwachsknochen') arises directly from the perichondrium of the two optic pilae and spreads in all directions and overlays the remaining cartilage and the endochondral ossifications. For some time, both bone types can be distinguished microscopically, but later in craniogenesis they fuse completely to become the presphenoid sensu lato of the osteocranium. We interpret the 'appositional bone' as neomorphic mode to reinforce the endocranial bone structures, which are the ossification of the delicate cartilaginous template of the chondrocranium. We studied the ossifications of the presphenoidal skull region in a series of ontogenetic stages of the pig Sus scrofa. We applied conventional histology as well as stained and unstained μCT scans. We can show the above-mentioned modes of ossification, and we can demonstrate the contribution of 'appositional bone' well into neonatal and infantile stages. The ossifications of the presphenoid (including the orbitosphenoid) are very slender in therapsids and early mammaliaforms as previously described by other authors. In mammaliaforms, they tend to become thicker and closely connected with the frontal bone, which may be due to the contribution of neomorphic appositional bone. We assume that thereby the presphenoid sensu lato becomes an enforcement of the orbital pillars.