Vertebral Morphology Research Articles

Vertebral column growth in children with early onset scoliosis treated with magnetically controlled growing rods – Effects of distraction on vertebral and disc morphology

ObjectivesTo report changes in vertebral and disc morphology following treatment of early onset scoliosis (EOS) with magnetically controlled growing rods (MCGR). Methods30 Patients, 21 girls and 9 boys, treated with MCGR for EOS were compared to a matched control group of 19 patients (12 girls, 7 boys) treated with bracing or observation. Age at surgery in the MCGR group was 8.75 (range: 4.6–11) years compared to 7.75 (range: 3.5–10.3) years in the control group at the time of onset of treatment. Mean follow-up was 45 (range: 24–65) months in the MCGR group vs 42 (range: 24–65) months in the control group.Calibrated radiographs were used to digitally measure disc height, vertebral body height, depth and width after surgery and at latest follow-up. Height, width and depth of lumbar and thoracic vertebrae and discs under distraction were compared to the control group and to vertebrae below instrumentation. T1-T12, T1-S1 length and Cobb angles were also measured. Results(1) There is a significant increase of lumbar vertebral height under distraction. (2) Lumbar disc height as well as lumbar vertebral width within distraction is significantly reduced. (3) Depth of lumbar vertebrae is not significantly affected by distraction. (4) Morphology of thoracic vertebrae and adjacent discs is not significantly changed with distraction. (5) T1-T12 distance did not show any significant changes between surgical and control group, while T1-S1 growth was significantly reduced compared to the control group. ConclusionsSignificant changes of morphology of lumbar vertebra and discs are observed under distraction with MCGR compared to segments below instrumentation and the control group. Level of evidenceLevel III – retrospective comparative series.

An automatic method for feature segmentation of human thoracic and lumbar vertebrae

Background and objectiveBecause of the three-dimensional distribution of morphological features of human vertebrae and the whole spine, in recent years, to make more precise diagnoses and to design optimized surgical procedures, new protocols have been proposed based on analysing their three-dimensional (3D) models. In the related literature, processes of segmentation and morphological features recognition are essentially performed by a skilled operator that selects the interesting areas. So, being affected by the preparation and experience of the operator, this produces an evaluation that is poorly reproducible and repeatable for the uncertainties of a typical manual measurement process. MethodsTo overcome this limitation, in this paper a new automatic method is proposed for feature segmentation and recognition of human vertebrae. The proposed computer-based method, starting from 3D high density discretized models of thoracic and lumbar vertebrae, automatically performs both the semantic and geometric segmentation of their morphological features. The segmentation and recognition rules codify some important definitions used in the traditional manual method, considering all the vertebra morphology information that is invariant inter-subject. ResultsThe automatic method proposed here is verified by analysing many real vertebrae, both acquired using a 3D scanner and coming from Computerized Tomography (CT) scans. The obtained results are critically discussed and compared with the traditional manual methods for vertebra analysis. The method has proven to be robust and reliable in the segmentation and recognition of morphological features of vertebrae. Furthermore, the proposed automatic method avoids the blurring of quantitative parameters get from vertebrae, resulting from poor repeatability and reproducibility of manual methods used in the state-of-the-art. ConclusionsStarting from the automatic segmentation and recognition here proposed, it is possible to automatically calculate the parameters of thoracic or lumbar vertebrae used in archaeology, medicine, or biomechanics or define their new ones.

Serial disparity in the carnivoran backbone unveils a complex adaptive role in metameric evolution

Organisms comprise multiple interacting parts, but few quantitative studies have analysed multi-element systems, limiting understanding of phenotypic evolution. We investigate how disparity of vertebral morphology varies along the axial column of mammalian carnivores — a chain of 27 subunits — and the extent to which morphological variation have been structured by evolutionary constraints and locomotory adaptation. We find that lumbars and posterior thoracics exhibit high individual disparity but low serial differentiation. They are pervasively recruited into locomotory functions and exhibit relaxed evolutionary constraint. More anterior vertebrae also show signals of locomotory adaptation, but nevertheless have low individual disparity and constrained patterns of evolution, characterised by low-dimensional shape changes. Our findings demonstrate the importance of the thoracolumbar region as an innovation enabling evolutionary versatility of mammalian locomotion. Moreover, they underscore the complexity of phenotypic macroevolution of multi-element systems and that the strength of ecomorphological signal does not have a predictable influence on macroevolutionary outcomes.

New records of legless squamates from the lowest upper Eocene deposits of the Fayum Depression, Egypt

ABSTRACT The Eocene was a key interval for the diversification of squamates worldwide. However, little is known about their early evolution in Africa due to the scarcity of Paleogene fossil squamates from that continent. One of the most important Eocene vertebrate assemblages in Africa is known from the Fayum Depression of Egypt, but only a few lizards and snakes have been reported from these deposits. Here we report the first Paleogene record of the clade Amphisbaenia in Egypt, from the lowest upper Eocene Birket Qarun Locality 2 (BQ-2). It corresponds to a mid-trunk vertebra characterized by a depressed centrum with a flattened base, hemispherical synapophyses, and absence of a neural spine. Additional material from BQ-2 includes seven vertebrae attributed to colubroidean snakes. One trunk vertebra resembles those of early Eocene Procerophis from India while the remaining colubroidean vertebrae are referred to Renenutet enmerwer. Caudal vertebrae of Renenutet are described here for the first time. Similarities in the caudal vertebral morphology between BQ-2 Renenutet and Thaumastophis missiaeni from the lower Eocene of India reinforce the hypothesis of a close affinity between them. The presence of cf. Procerophis and Renenutet in Egypt adds to the evidence for terrestrial faunal exchange between Asia and northern Africa during the early/middle Eocene along the southern margin of the Tethyan Sea.

Transitional vertebrae and numerical variants of the spine : prevalence and relationship to low back pain or degenerative spondylolisthesis.

Although lumbosacral transitional vertebrae (LSTV) are well-documented, few large-scale studies have investigated thoracolumbar transitional vertebrae (TLTV) and spinal numerical variants. This study sought to establish the prevalence of numerical variants and to evaluate their relationship with clinical problems. A total of 1,179 patients who had undergone thoracic, abdominal, and pelvic CT scanning were divided into groups according to the number of thoracic and lumbar vertebrae, and the presence or absence of TLTV or LSTV. The prevalence of spinal anomalies was noted. The relationship of spinal anomalies to clinical symptoms (low back pain, Japanese Orthopaedic Association score, Roland-Morris Disability Questionnaire) and degenerative spondylolisthesis (DS) was also investigated. Normal vertebral morphology (12 thoracic and five lumbar vertebrae without TLTV and LSTV) was present in 531 male (76.7%) and 369 female patients (75.8%). Thoracolumbar transitional vertebrae were present in 15.8% of males and 16.0% of females. LSTV were present in 7.1% of males and 9.0% of females. The prevalence of the anomaly of 16 presacral mobile vertebrae (total number of thoracolumbar vertebrae and TLTV) without LSTV was 1.0% in males and 4.1% in females, and that of the anomaly of 18 vertebrae without LSTV was 5.3% in males and 1.2% in females. The prevalence of DS was significantly higher in females with a total of 16 vertebrae than in those with normal morphology. There was no significant correlation between a spinal anomaly and clinical symptoms. Overall, 24% of subjects had anomalies in the thoracolumbar region: the type of anomaly differed between males and females, which could have significant implications for spinal surgery. A decreased number of vertebrae was associated with DS: numerical variants may potentially be a clinical problem. Cite this article: Bone Joint J2021;103-B(7):1301-1308.

Foretelling the Flex-Vertebral Shape Predicts Behavior and Ecology of Fishes.

One key evolutionary innovation that separates vertebrates from invertebrates is the notochord, a central element that provides the stiffness needed for powerful movements. Later, the notochord was further stiffened by the vertebrae, cartilaginous, and bony elements, surrounding the notochord. The ancestral notochord is retained in modern vertebrates as intervertebral material, but we know little about its mechanical interactions with surrounding vertebrae. In this study, the internal shape of the vertebrae-where this material is found-was quantified in 16 species of fishes with various body shapes, swimming modes, and habitats. We used micro-computed tomography to measure the internal shape. We then created and mechanically tested physical models of intervertebral joints. We also mechanically tested actual vertebrae of five species. Material testing shows that internal morphology of the centrum significantly affects bending and torsional stiffness. Finally, we performed swimming trials to gather kinematic data. Combining these data, we created a model that uses internal vertebral morphology to make predictions about swimming kinematics and mechanics. We used linear discriminant analysis (LDA) to assess the relationship between vertebral shape and our categorical traits. The analysis revealed that internal vertebral morphology is sufficient to predict habitat, body shape, and swimming mode in our fishes. This model can also be used to make predictions about swimming in fishes not easily studied in the laboratory, such as deep sea and extinct species, allowing the development of hypotheses about their natural behavior.

Computerized Tomographic Based Study of Thoracic Spine Morphology in Relevance to Pedicle Screw Fixation in Pakistani Population

Objective: To study the thoracic spine anatomy for accurate placement of pedicle screws using computerized tomography.
 Material and Methods: CT scans of 200 patients were included in our study. T1 to T12 vertebrae morphology was studied for each patient. Following measurements were taken, 1: Transverse pedicle width, 2 = Depth of anterior cortex along pedicle axis, 3 = Transverse pedicle angle, 4 = canal dimensions, 5 = vertebral body height anterior and posterior, 6 = mid vertebral body width.
 Results: Transverse pedicle width decreased from T1 (4.06 ± 0.50 mm) to T4 (3.72 ± 0.17 mm) and then gradually increases to T12 (6.08 ± 0.60 mm). Depth of the anterior vertebral cortex remained constant from T1 to T4 and gradually increases up to T12. Transverse pedicle angle remained constant from T1 to T4 with a maximum at T4 (23.39 ± 3.15 mm) and then gradually decreased to T12 (3.99 ± 2.16 mm). Anteroposterior (AP) canal dimensions were minimum at T7 (17.03 ± 1.01 mm) and maximum at T2 (21.2 ± 1.07 mm). Interpedicular (IPD) canal dimensions were minimum at T6 (19.18 ± 1.6 mm) and maximum at T3 (23.18 ± 1.2 mm). Anterior vertebral body height was minimum at T1 (16.9 ± 1.34 mm) and maximum at T12 (27.14 ± 1.34mm). Posterior vertebral body height was minimum at T1 (18.8 ± 1.13 mm) and maximum at T12 (29.76 ± 1.43 mm).
 Conclusion: A detailed anatomy of the thoracic spine is essential for surgical planning to decrease postoperative complications.

Two heads are not always better than one: Craniofacial and axial bifurcation in cheloniid embryos and hatchlings (Chelonia mydas and Caretta caretta).

Morphological data on craniofacial and axial bifurcation in sea turtles is not well documented in the literature. Here, we use micro-computed tomography (μ-CT) imaging to describe the body, skull, and vertebral morphology in axially-bifurcated cheloniid sea turtle embryos and hatchlings (Chelonia mydas and Caretta caretta) from south Florida beaches. We describe three types of craniofacial and axial bifurcations: bifacial, bicephalic, and bicephalic with biaxial duplication ranging from facial bones to the sacrum. We predicted smaller body dimensions in bifacial and bicephalic embryos and hatchlings compared with their normal counterparts. In addition, we hypothesized that bicephalic individuals would have greater rostral deviation angles than bifacial animals, and that vertebral dimensions would vary between the control and anomalous embryos and hatchlings. Among hatchlings (developmental Stage 31), we found that maximum curved carapace length and curved carapace width were greatest in the control specimens when compared with the anomalous specimens. Overall, we found that rostral deviations were smaller in bifacial animals compared with their bicephalic counterparts. Right and left rostral deviations were symmetrical or nearly symmetrical in all bifacial and bicephalic specimens. Among C. caretta, we found that bicephalic animals had greater standardized vertebral measurements than their bifacial conspecifics. In bifacial animals, bifurcation extended to either the frontal or parietal skull bones, while duplication extended to C5 vertebrae and T8 vertebrae in bicephalic animals. This study provides an in-depth description of anatomical alterations associated with these abnormalities. Prognosis of these organisms is poor; however, understanding the prevalence of these malformations can allow for better assessments of population health, as numerous environmental factors are known to lead to these changes.

Examination of magnitudes of integration in the catarrhine vertebral column

The evolution of novel vertebral morphologies observed in humans and other extant hominoids may be related to changes in the magnitudes and/or patterns of covariation among traits. To examine this, we tested magnitudes of integration in the vertebral column of cercopithecoids and hominoids, including humans. Three-dimensional surface scans of 14 vertebral elements from 30 Cercopithecus, 32 Chlorocebus, 39 Macaca, 45 Hylobates, 31 Pan, and 86 Homo specimens were used. A resampling method was used to generate distributions of integration coefficient of variation scores for vertebral elements individually using interlandmark distances. Interspecific comparisons of mean integration coefficient of variation were conducted using Mann–Whitney U tests with Bonferroni adjustment. The results showed that hominoids generally had lower mean integration coefficient of variation than cercopithecoids. In addition, humans showed lower mean integration coefficient of variation than other hominoids in their last thoracic and lumbar vertebrae. Cercopithecoids and Hylobates showed relatively lower mean integration coefficient of variation in cervical vertebrae than in thoracolumbar vertebrae. Pan and Homo showed relatively lower mean integration coefficient of variation in the last thoracic and lumbar vertebrae in the thoracolumbar region, except for the L1 of Pan. The results suggest fewer integration-mediated constraints on the evolution of vertebral morphology in hominoids when compared with cercopithecoids. The weaker magnitudes of integration in lumbar vertebrae in humans when compared with chimpanzees likewise suggest fewer constraints on the evolution of novel lumbar vertebrae morphology in humans.

Body shape transformations by alternate anatomical adaptive peak shifts in blenniiform fishes.

Extreme body elongation has occurred repeatedly in the evolutionary history of ray-finned fishes. Lengthening of the anterior-posterior body axis relative to depth and width can involve changes in the cranial skeleton and vertebral column, but to what extent is anatomical evolution determined by selective factors and intrinsic constraints that are shared broadly among closely related lineages? In this study, we fit adaptive (Ornstein-Uhlenbeck) evolutionary models to body shape and its anatomical determinants and identified two instances of extreme elongation by divergent anatomical peak shifts in the Blenniiformes, a radiation of small-bodied substrate-associated marine teleost fishes. Species in the genus Xiphasia (hairtail blennies) evolved toward a peak defined by a highly elongated caudal vertebral region but ancestral cranial and precaudal vertebral morphology. In contrast, a clade that includes the genera Chaenopsis and Lucayablennius (pike and arrow blennies) evolved toward a peak with a long slender skull but ancestral axial skeletal anatomy. Neither set of anatomical peak shifts aligns closely with the major axis of anatomical diversification in other blenniiform fishes. These results provide little evidence that ancestral constraints have affected body shape transformation, and instead suggest that extreme elongation arose with distinct shifts in selective factors and development.

A Tail of Four Fishes: An Analysis of Kinematics and Material Properties of Elongate Fishes.

The elongate body plan is present in many groups of fishes, and this morphology dictates functional consequences seen in swimming behavior. Previous work has shown that increasing the number of vertebrae, or decreasing the intervertebral joint length, in a fixed length artificial system increases stiffness. Tails with increased stiffness can generate more power from tail beats, resulting in an increased mean swimming speed. This demonstrates the impacts of morphology on both material properties and kinematics, establishing mechanisms for form contributing to function. Here, we wanted to investigate relationships between form and ecological function, such as differences in dietary strategies and habitat preferences among fish species. This study aims to characterize and compare the kinematics, material properties, and vertebral morphology of four species of elongate fishes: Anoplarchus insignis, Anoplarchus purpurescens, Xiphister atropurpureus, and Xiphister mucosus. We hypothesized that these properties would differ among the four species due to their differential ecological niches. To calculate kinematic variables, we filmed these fishes swimming volitionally. We also measured body stiffness by bending the abdominal and tail regions of sacrificed individuals in different stages of dissection (whole body, removed skin, and removed muscle). Finally, we counted the number of vertebrae from CT scans of each species to quantify vertebral morphology. Principal component and linear discriminant analyses suggested that the elongate fish species can be distinguished from one another by their material properties, morphology, and swimming kinematics. With this information combined, we can draw connections between the physical properties of the fishes and their ecological niches.

Exaggerated Premature Adrenarche in Boys: Comparative Study of a Therapeutic Intervention With the Aromatase Inhibitor Anastrozole Versus Morning Low Dose Hydrocortisone

Abstract Background: In boys, idiopathic premature adrenarche (IPA) is defined as the appearance of pubic or axillary hair/odor before the age of 9 yrs, not due to pathology of the adrenal glands. Exaggerated Adrenarche (EXAD), occurring in 10-15% of children with IPA, is characterized by an elevated >10 DHEA/Δ4 ratio (theoretically indicating reduced 3-β-HSD activity) and accelerated bone age (BA) maturation, continuously increasing the projecting distance from the target height (TH) curve, beyond the one observed in the pattern of Constitutional Advancement of Growth (CAG), eventually leading to short stature (SS). It is traditionally successfully treated with a morning (6-8 am) low dose of hydrocortisone (8 mg/m2) in order to reduce the androgens produced and delay BA progression, similarly to the standard treatment of non-classical (late-onset) CAH. Third generation aromatase inhibitors (AI) have been shown to delay BA by inhibiting the peripheral aromatization of androgens and are being widely used off-label to treat short SS in boys. Aims: To evaluate the effectiveness of the AI anastrozole in delaying BA in boys with EXAD. Methods: 39 boys with advanced BA and a predicted adult height (PAH) <170cm and > -1SDS from TH) were included. Group-A (n=28) received anastrozole 1mg x 1 p.o. and group-B (n=11) low dose (8 mg/m2) hydrocortisone at 6-8 am for at least 3 yrs. All measurements were made on the same height meter by the same examiner. The two groups did not differ in terms of age at intervention onset: 8.6 in group A vs 8.74 yrs in group B, TH: 175.7 vs 175.7 cm, PAH: 168.4 vs 167.8 cm and BA advancement: +2.3 yrs in group A vs +2.4 yrs in group B. A 6-month follow-up included clinical examination, BA assessment, and laboratory tests (general blood, lipid chart, LH, FSH, TESTO, E2, E1, and complete calcium metabolism). Lumbar spine DEXA scan and X-Ray was performed on an annual basis. Results: Both groups had a statistically significant gain in PAH after 3yrs of treatment: Group A +10.3 cm (1.53 SD), p<0.001, and group B +7.1 cm (1.06 SD), p=0.007. Thus, group A exceeded their TH by +3cm (0.45 SDS) and group B reached -0.8cm (-0.11 SDS) from their TH, p=0.03. The reduction of BA advancement was statistically significant in both groups (p<0.05), with superiority of the anastrozole-treated group: at 3yrs in group A BA advancement was +0.48 yrs, and at group B +1.24 yrs (p<0.001). No clinical adverse events or abnormal tests were noted in any of the groups. Bone density and vertebral morphology was not affected within or between groups. Conclusions: Aromatase Inhibitors may have a place in managing exaggerated adrenarche in boys, showing superiority to traditional low-dose hydrocortisone in improving predicted adult height and delaying bone age maturation, but notably by overcoming quality of life and compliance issues associated with hydrocortisone therapy (mandatory 6-8 am).

Integration between the bony nasopharynx and the cervical vertebrae in Homo and Pan

Hominin evolution is marked by an increase in the size of the brain and concomitant reorganization of the face and basicranium. As a result, modern human crania are drastically different from those of our closest relatives, including in the nasopharyngeal region, which is necessary for vital life functions such as respiration. The maintenance of nasopharyngeal function serves as an important constraint on the development of surrounding structures, and researchers have documented extensive potential negative consequences. However, little is known about the impact of these functional constraints on the cervical vertebrae, which form the posterior border of the nasopharynx. We tested whether the atlas, axis, face, and the cranial boundaries of the nasopharynx form an integrated module using three-dimensional coordinate data from recent Homo (N =80) and Pan (N =44). We used two-block partial least squares (2B-PLS) to obtain RV values, covariance ratios, and z-scores for each of the following potential modules: nasopharynx-face, nasopharynx-atlas, nasopharynx-axis, face-atlas, face-axis, atlas-axis. P-values were obtained using 999 to 1000 random permutations. Analyses were carried out on MorphoJ and in R using the geomorph package. Our results confirm previous findings that the nasopharynx and face form an integrated module across taxa (Effect size =14.0185, CR =1.0296, P =0.001) but this relationship is weaker within Homo and within Pan. In addition, our results suggest that across taxa the atlas and axis are integrated with the face and nasopharynx (CR = 1.0206-1.058) to a greater extent than they are to each other (CR =0.7797, P =0.001), though again within taxa this effect is less clear. Finally, covariation tends to be stronger between the axis and nasopharynx (Effect size =9.4830), and between the axis and face (Effect size =9.0196), than between the atlas and any structure (Effect size =8.4396-8.7139). However, this difference was not statistically significant and again became less clear within taxa. Together, these results suggest that, across hominids, nasopharyngeal function may be constraining upper cervical vertebral morphology, and especially axis morphology, at least to the same extent as the vertebrae affect each other, if not more. Nonetheless, the importance of these different relationships may vary in different taxa. Future research should focus on clarifying relationships within taxa with larger samples, and expanding the analysis to additional taxa.

Bendy to the bone: Links between vertebral morphology and waterfall climbing in amphidromous gobioid fishes.

Locomotor force production imposes strong demands on organismal form. Thus, the evolution of novel locomotor modes is often associated with morphological adaptations that help to meet those demands. In the goby lineage of fishes, most species are marine and use their fused pelvic fins to facilitate station holding in wave-swept environments. However, several groups of gobies have evolved an amphidromous lifecycle, in which larvae develop in the ocean but juveniles migrate to freshwater for their adult phase. In many of these species, the pelvic fins have been co-opted to aid in climbing waterfalls during upstream migrations to adult habitats. During horizontal swimming, forces are produced by axial musculature pulling on the vertebral column. However, during vertical climbing, gravity also exerts forces along the length of the vertebral column. In this study, we searched for novel aspects of vertebral column form that might be associated with the distinctive locomotor strategies of climbing gobies. We predicted that stiffness would vary along the length of the vertebral column due to competing demands for stability of the suction disk anteriorly and flexibility for axial thrust production posteriorly. We also predicted that derived, climbing goby species would require stiffer backbones to aid in vertical thrust production compared to non-climbing species. To test these predictions, we used microcomputed tomography scans to compare vertebral anatomy (centrum length, centrum width, and intervertebral space) along the vertebral column for five gobioid species that differ in climbing ability. Our results support our second prediction, that gobies are more flexible in the posterior portion of the body. However, the main variation in vertebral column form associated with climbing ability was the presence of larger intervertebral spaces in Sicyopterus stimpsoni, a species that uses a distinctive inching behavior to climb. These results build on past kinematic studies of goby climbing performance and lend insights into how the underlying vertebral structure of these fishes may enable their novel locomotion.

Adolescent idiopathic scoliosis 3D vertebral morphology, progression and nomenclature: a current concepts review.

There has been a recent shift toward the analysis of the pathoanatomical variation of the adolescent idiopathic scoliosis (AIS) spine with the three dimensions, and research of level-wise vertebral body morphology in single anatomical planes is now replete within the field. In addition to providing a precise description of the osseous structures that are the focus of instrumented surgical interventions, understanding the anatomical variation between vertebral bodies will elucidate possible pathoaetiological mechanisms of the onset of scoliotic deformity. This review aimed to discuss the current landscape of AIS segmental vertebral morphology research and provide a comprehensive report of the typical patterns observed at the individual vertebral level. We have detailed how these vertebrae are typically characterised by lateral wedging to the convexity, have a marked degree of anterior overgrowth, are rotated towards the convexity, have inherent gyratory mechanical torsion created within them and are associated with pedicles on the concave side being narrower, longer and more laterally angled. For the most part, these findings are most pronounced at and around the apex of a scoliotic curve, with these deformations reducing towards junctional vertebrae. We have also summarised a nomenclature defined by the Scoliosis Research Society, highlighting the need for more consistent reporting of these level-wise dimensional anatomical changes. Finally, we emphasised how a marked degree of heterogeneity exists between the included investigations, namely in scoliotic curve-type inclusion, imaging modality and timepoint of analysis within scoliosis' longitudinal development, and how improvement in these study design characteristics will enhance ongoing research.

Skeletal remains of the oldest known pseudocoracid shark Pseudocorax kindlimanni sp. nov. (Chondrichthyes, Lamniformes) from the Late Cretaceous of Lebanon

A new fossil mackerel shark, Pseudocorax kindlimanni sp. nov. (Lamniformes, Pseudocoracidae), is described from the Cenomanian Konservat-Lagerstätte of Haqel, Lebanon. The new species is based on the most complete fossil of this group to date, which comprises an associated tooth set of 70 teeth, six articulated vertebral centra, numerous placoid scales and pieces of unidentifiable mineralized cartilage. The dentition of P. kindlimanni sp. nov. is marked by a high degree of monognathic heterodonty but does not exhibit the characteristic “lamnoid tooth pattern” known from other macrophagous lamniform sharks. In addition, P. kindlimanni sp. nov. shows differences in tooth microstructure and vertebral centrum morphology compared to other lamniform sharks. These variations, however, are also known from other members of this order and do not warrant the assignment of Pseudocorax outside the lamniform sharks. The new fossil is the oldest known pseudocoracid shark and pushes the origin of this group back into the Cenomanian, a time when lamniform sharks underwent a major diversification. This radiation resulted not only in high species diversity, but also in the development of a diverse array of morphological traits and adaptation to different ecological niches. Pseudocorax kindlimanni sp. nov. was a small, active predator capable of fast swimming, and it occupied the lower trophic levels of the marine food web in the Late Cretaceous.

Morphometry of Dry Sub Axial Vertebra: A Nepalese Study

There is paucity in literature describing the morphology of sub-axial vertebra of the local population. Available studies are limited to the body, intervertebral disk, spinal canal and Torg’s ratio of the cervical vertebra. Therefore, the present study aims to document various morphological parameters of sub axial vertebra. Sixty-four dry sub-axial vertebrae of the Nepalese population were studied using Vernier Calipers calibrated to 0.1 mm accuracy. Paired parameters of pedicle, lamina, uncinate process, the distance of the apex of the uncinate process to intervertebral foramen and foramen transversarium were measured. Similarly, unpaired parameters including spinous process length, vertebral foramen anteroposterior width, vertebral foramen transverse diameter and Torg’s ratio were evaluated. Except the height of left lamina of C3 to C6 vertebrae, none of the parameters showed significant side differences. Significant higher values of C7 were noted against C3-C6 on vertebral body height, vertebral body anteroposterior diameter, spinous process length and vertebral foramen anteroposterior diameter. Population data of sub-axial vertebra available in literature showed mixed results with ours. Interestingly, our observations either compared to (lamina, uncinate process, anteroposterior diameter of spinal canal and Torg’s ratio) or were larger (Pedicle and spinous process) than the Indian study with pedicle axis length being largest among all the compared studies. The information of this study may be used as a reference database for our local setting and could be of value in preoperative planning and in designing implants.

Predictability of skeletal sagittal and vertical jaw relationship with its correlation to cervical vertebral morphometry and cervical spine inclination

The cervical vertebra and its relation to maxilla and mandible is of particular interest to orthodontist due to their correlated developmental and anatomical relationship. The aim of the study is to evaluate and correlate the relationship between cervical vertebral morphology and cervical spine inclination with skeletal sagittal jaw relationship and growth pattern for an individual. Cephalogram of 30 subjects was divided in 3 groups based on ANB angle. All the craniofacial and craniocervical landmarks that are required to be analysed were recorded and it was concluded that class III patients had more posterior inclination of dens axis of CV2 but straighter spine inclination on subsequent arches. EVT/VER values indicated more enhanced curvature of vertical column in class II and class III patients. Morphological assessment of CV1SL & CV1HT revealed significantly less measurements in Class III that among class I and II subjects. CV2BL measurement in class II & III was significantly more than class. CV3Sl was significantly more in class III and CV3BL was significantly less in class II.

The Role of Vertebral Porosity and Implant Loading Mode on Bone-Tissue Stress in the Human Vertebral Body Following Lumbar Total Disc Arthroplasty.

Micro-computed tomography- (micro-CT-) based finite element analysis of cadaveric human lumbar vertebrae virtually implanted with total disc arthroplasty (TDA) implants. (1) Assess the relationship between vertebral porosity and maximum levels of bone-tissue stress following TDA; (2) determine whether the implant's loading mode (axial compression vs. sagittal bending) alters the relationship between vertebral porosity and bone-tissue stress. Implant subsidence may be related to the bone biomechanics in the underlying vertebral body, which are poorly understood. For example, it remains unclear how the stresses that develop in the supporting bone tissue depend on the implant's loading mode or on typical inter-individual variations in vertebral morphology. Data from micro-CT scans from 12 human lumbar vertebrae (8 males, 4 females; 51-89 years of age; bone volume fraction [BV/TV] = 0.060-0.145) were used to construct high-resolution finite element models (37 μm element edge length) comprising disc-vertebra-implant motion segments. Implants were loaded to 800 N of force in axial compression, flexion-, and extension-induced impingement. For comparison, the same net loads were applied via an intact disc without an implant. Linear regression was used to assess the relationship between BV/TV, loading mode, and the specimen-specific change in stress caused by implantation. The increase in maximum bone-tissue stress caused by implantation depended on loading mode (P < 0.001), increasing more in bending-induced impingement than axial compression (for the same applied force). The change in maximum stress was significantly associated with BV/TV (P = 0.002): higher porosity vertebrae experienced a disproportionate increase in stress compared with lower porosity vertebrae. There was a significant interaction between loading mode and BV/TV (P = 0.002), indicating that loading mode altered the relationship between BV/TV and the change in maximum bone-tissue stress. Typically-sized TDA implants disproportionately increase the bone-tissue stress in more porous vertebrae; this affect is accentuated when the implant impinges in sagittal bending.Level of Evidence: N/A.

Adaptive landscapes challenge the “lateral-to-sagittal” paradigm for mammalian vertebral evolution

The evolution of mammals from their extinct forerunners, the non-mammalian synapsids, is one of the most iconic locomotor transitions in the vertebrate fossil record. In the limb skeleton, the synapsid-mammal transition is traditionally characterized by a shift from a sprawling limb posture, resembling that of extant reptiles and amphibians, to more adducted limbs, as seen in modern-day mammals. Based on proposed postural similarities between early synapsids and extant reptiles, this change is thought to be accompanied by a shift from ancestral reptile-like lateral bending to mammal-like sagittal bending ofthe vertebral column. To test this "lateral-to-sagittal" evolutionary paradigm, we used combinatorial optimization to produce functionally informed adaptive landscapes and determined the functional trade-offs associated with evolutionary changes in vertebral morphology. We show that the synapsid adaptive landscape is different from both extant reptiles and mammals, casting doubt on the reptilian model for early synapsid axial function, or indeed for the ancestral condition of amniotes more broadly. Further, the synapsid-mammal transition is characterized by not only increasing sagittal bending in theposterior column but also high stiffness and increasing axial twisting in the anterior column. Therefore,we refute the simplistic lateral-to-sagittal hypothesis and instead suggest the synapsid-mammal locomotor transition involved a more complex suite of functional changes linked to increasing regionalization of the backbone. These results highlight the importance of fossil taxa for understanding major evolutionary transitions.