A new specimen of Biseridens qilianicus indicates its phylogenetic position as the most basal anomodont

A new well-preserved basal therapsid skull from the Xidagou Formation, Middle Permian of China, is identified as Biseridens qilianicus. The following synapomorphies distinguish Biseridens as an anomodont and not an eotitanosuchian as previously described: short snout; dorsally elevated zygomatic arch and septomaxilla lacking elongated posterodorsal process between nasal and maxilla. The presence of a differentiated tooth row; denticles on vomer, palatine and pterygoid; contact between tabular and opisthotic; lateral process of transverse flange of pterygoid free of posterior ramus and absence of mandibular foramen exclude it from other anomodonts. Our cladistic analysis indicates Biseridens to be the most basal anomodont, highlights separate Laurasian and Gondwanan basal anomodont clades and suggests that dicynodonts had their origins in the Gondwanan clade. The co-occurrence of the most basal anomodont (Biseridens) together with the most basal therapsid (Raranimus), basal anteosaurid dinocephalians, bolosaurids and dissorophids suggests that the earliest therapsid faunas are from China.     

What did the “Unossified zone” of the non‐mammalian therapsid braincase house?

Most nonmammalian synapsids possess a mid‐dorsal depression in the brain cavity known as the “unossified zone.” It remains obscure which structures this zone contained, and, as candidates, the vermis of the cerebellum, the superior sagittal sinus, a junction of several blood vessels, the pineal gland or other midbrain structures were considered. Neutron tomography of a skull of Diictodon feliceps (Therapsida, Anomodontia) revealed some clear impressions of canals in this region of the brain cavity. Furthermore, the prootic sinus probably ran on the internal surface of the pila antotica and had a similar course in anomodonts as it has been proposed for cynodonts and Mesozoic mammals. Comparisons with the vascular systems of nonmammalian synapsids and mammals suggest that the unossified zone is best interpreted as a terminal chamber of the anterior segment of the medial head vein, which housed the junction of the superior sagittal sinus and the transverse sinuses. Consequently, the system of cranial vessels in Diictodon reveals a partial division of the medial head vein system into an anterior and a posterior segment at an early stage of synapsid evolution, which is consistent with the well‐known common pattern of early ontogenetic development in amniotes. J. Morphol., 2017. © 2017 Wiley Periodicals, Inc.     

A primitive anomodont therapsid from the base of the Beaufort Group (Upper Permian) of South Africa

Patranomodon nyaphulii , known from a nearly complete skull, lower jaw and partial postcranial skeleton, is morphologically the most primitive anomodont therapsid yet discovered. It is from the Eodicynodon Assemblage Zone, the lowest biozone of the Beaufort Group of South Africa, which has a primitive therapsid fauna comparable with that of the Russian Zone I. Patranaomodon is primitive with respect to other anomodonts in having short palatal exposure of the premaxilla, an unreduced tabular, a slit-like interpterygoidal vacuity, a screw-shaped jaw articulation (which precludes fore-aft sliding of the lower jaw), and only three sacral vertebrae. The poorly-known Galechirus and Galepus from the younger Cistecephalus Assemblage Zone appear to be at a comparably primitive evolutionary grade, and the three genera are tentatively united in the family Galechiridae. The taxon Dromasauria is shown to be paraphyletic and therefore should be discarded.     

Instrumental neutron activation analysis of rib bone samples and of bone reference materials

The instrumental neutron activation analysis method was used for the determination of trace elements in rib bone samples taken from autopsies of accident victims. The elements Br, Ca, Cl, Cr, Fe, Mg, Mn, Na, P, Sr, Rb, and Zn were determined in cortical tissues by using short and long irradiations with thermal neutron flux of the IEA-R1m nuclear reactor. The reference materials NIST SRM 1400 Bone Ash and NIST SRM 1486 Bone Meal were also analyzed in order to evaluate the precision and the accuracy of the results. It was verified that lyophilization is the most convenient process for drying bone samples because it does not cause any element losses. Comparisons were made between the results obtained for rib samples and the literature values as well as between the results obtained for different ribs from a single individual and for bones from different individuals.     

Micro-finite element simulation of trabecular-bone post-yield behaviour – effects of material model,element size and type

Micro-finite element (micro-FE) analysis became a standard tool for the evaluation of trabecular bone mechanical properties. The accuracy of micro-FE models for linear analyses is well established. However, the accuracy of recently developed nonlinear micro-FE models for simulations of trabecular bone failure is not known. In this study, a trabecular bone specimen was compressed beyond the apparent yield point. The experiment was simulated using different micro-FE meshes with different element sizes and types, and material models based on cortical bone. The results from the simulations were compared with experimental results to study the effects of the different element and material models. It was found that a decrease in element size from 80 to 40 μm had little effect on predicted post-yield behaviour. Element type and material model had significant effects. Nevertheless, none of the established material models for cortical bone were able to predict the typical descent in the load-displacement curve seen during compression of trabecular bone.     

Does skeletal anatomy reflect adaptation to locomotor patterns? cortical and trabecular architecture in human and nonhuman anthropoids

Although the correspondence between habitual activity and diaphyseal cortical bone morphology has been demonstrated for the fore- and hind-limb long bones of primates, the relationship between trabecular bone architecture and locomotor behavior is less certain. If sub-articular trabecular and diaphyseal cortical bone morphology reflects locomotor patterns, this correspondence would be a valuable tool with which to interpret morphological variation in the skeletal and fossil record. To assess this relationship, high-resolution computed tomography images from both the humeral and femoral head and midshaft of 112 individuals from eight anthropoid genera (Alouatta, Homo, Macaca, Pan, Papio, Pongo, Trachypithecus, and Symphalangus) were analyzed. Within-bone (sub-articular trabeculae vs. mid-diaphysis), between-bone (forelimb vs. hind limb), and among-taxa relative distributions (femoral:humeral) were compared. Three conclusions are evident: (1) Correlations exists between humeral head sub-articular trabecular bone architecture and mid-humerus diaphyseal bone properties; this was not the case in the femur. (2) In contrast to comparisons of inter-limb diaphyseal bone robusticity, among all species femoral head trabecular bone architecture is significantly more substantial (i.e., higher values for mechanically relevant trabecular bone architectural features) than humeral head trabecular bone architecture. (3) Interspecific comparisons of femoral morphology relative to humeral morphology reveal an osteological \"locomotor signal\" indicative of differential use of the forelimb and hind limb within mid-diaphysis cortical bone geometry, but not within sub-articular trabecular bone architecture.     

Bone conduction and seismic sensitivity in golden moles (Chrysochloridae)

Some genera of golden moles are known to possess enormously hypertrophied auditory ossicles. These structures have been implicated as potentially mediating a form of inertial bone conduction, used by the golden mole to detect seismic vibrations. A simple model of ossicular inertial bone conduction, based on an existing model of the human middle ear from the literature, was used in an attempt to examine vibrational sensitivity in these animals. Those golden moles with hypertrophied ossicles are predicted to possess a sensitive inertial bone conduction response at frequencies below a few hundred hertz, whereas species lacking these middle ear adaptations are predicted to have a far less sensitive response in this ecologically important frequency range. An alternative mode of inertial bone conduction in golden moles, potentially conferring sensitivity to vertically-polarized seismic vibrations such as Rayleigh waves, is proposed. Certain behaviours of golden moles described in the literature are interpreted as augmenting seismic sensitivity.     

CAD–CAM prosthetically guided bone regeneration using preformed titanium mesh for the reconstruction of atrophic maxillary arches

The protocol presented here is intended to minimise the intervention in bone reconstruction surgery when severe atrophy or deformity is present in the maxillary arches. A patient underwent augmentation of an atrophic maxillary arch using titanium mesh and particulate autogenous plus bovine demineralised bone. After computed tomography data elaboration, computer-aided design and computer-aided machining were used to plan the augmentation of bone volume to improve the implant position needed to support the final dental prosthesis. The augmented maxilla was rapidly prototyped in plastic, and the titanium mesh was tested on this model before the surgical intervention. Then, the preformed titanium mesh was implanted in the maxillary arch with bone grafting. The bone was augmented relative to the position of the implants for the definitive fixed implant-supported rehabilitation. The protocol presented here is a viable, reproducible way to determine the correct bone augmentation for the final implant-supported prosthetic rehabilitation.     

Convergence vs. Specialization in the ear region of moles (mammalia)

We investigated if and how the inner ear region undergoes similar adaptations in small, fossorial, insectivoran‐grade mammals, and found a variety of inner ear phenotypes. In our sample, afrotherian moles (Chrysochloridae) and the marsupial Notoryctes differ from most other burrowing mammals in their relatively short radii of semicircular canal curvature; chrysochlorids and fossorial talpids share a relatively long interampullar width. Chrysochlorids are unique in showing a highly coiled cochlea with nearly four turns. Extensive cochlear coiling may reflect their greater ecological dependence on low frequency auditory cues compared to talpids, tenrecids, and the marsupial Notoryctes. Correspondingly, the lack of such extensive coiling in the inner ear of other fossorial species may indicate a greater reliance on other senses to enable their fossorial lifestyle, such as tactile sensation from vibrissae and Eimer's organs. The reliance of chrysochlorids on sound is evident in the high degree of coiling and in the diversity of its mallear types, and may help explain the lack of any semiaquatic members of that group. The simplest mallear types among chrysochlorids are not present in the basal‐most members of that clade, but all extant chrysochlorids investigated to date exhibit extensive cochlear coiling. The chrysochlorid ear region thus exhibits mosaic evolution; our data suggest that extensive coiling evolved in chrysochlorids prior to and independently of diversification in middle ear ossicle size and shape. J. Morphol. 276:900–914, 2015. © 2015 Wiley Periodicals, Inc.     

Design and validation of a testing system to assess torsional cancellous bone failure in conjunction with time-lapsed micro-computed tomographic imaging

When compressed axially, cancellous bone often fails at an oblique angle along well-defined bands, highlighting the importance of cancellous bone shear properties. Torsion testing to determine shear properties of cancellous bone has often been conducted under conditions appropriate only for axis-symmetric specimens comprised of homogeneous and isotropic materials. However, most cancellous bone specimens do not meet these stringent test conditions. Therefore, the aim of this study was to design and validate a uniaxial, incremental torsional testing system for non-homogeneous orthotropic or non-axis-symmetric specimens.Precision and accuracy of the newly designed torsion system was validated by using Plexiglas rods and beams, where obtained material properties were compared to those supplied by the manufacturer. Additionally, the incremental step-wise application of angular displacement and simultaneous time-lapsed μCT imaging capability of the system was validated using whale cancellous bone specimens, with step-wise application of angular displacement yielding similar torsional mechanical properties to continuous application of angular displacement in a conventional torsion study.In conclusion, a novel torsion testing system for non-homogeneous, orthotropic materials using the incremental step-wise application of torsion and simultaneous time-lapsed μCT imaging was designed and validated.     

Calcium,phosphorus, calcium-phosphorus ratio in rib bone of healthy humans

Calcium and phosphorus concentrations as well as the Ca/P ratio were estimated in intact rib bone samples from healthy humans, 37 women and 45 men, aged 15–55 yr. For Ca and P concentration measurements, instrumental neutron activation analysis was used. The mean values (mean±SD) for the investigated parameters were 19.3±4.5% of dry bone weight, 8.42±2.14% of dry bone weight, and a ratio of 2.33±0.34, respectively. Statistically significant differences for the above parameters were not observed to be related either to age or sex. The mean values for Ca, P, and the Ca/P ratio were within a very wide range of published data and close to their medians. The individual variation for the Ca/P ratio in rib bone from healthy humans was lower than those for Ca and P taken separately. An indication is that the specificity of the Ca/P ratio improves upon that for Ca and P concentrations and may be more reliable in the diagnosis of bone disorders.