Background:As science becomes more open and accessible, researchers are increasingly encouraged-and sometimes required-to share their digital data on public repositories. While this promotes transparency and reusability, it can also introduce challenges. We highlight one such challenge by detailing our experience processing computerized tomography (CT) scans of 985 baboon skulls downloaded from MorphoSource, part of a quantitative genetic study of craniodental variation in the pedigreed baboon colony from the Southwest National Primate Research Center. When importing DICOM files into 3D Slicer, 182 of the 985 scans (18.5%) generated an "inconsistent slice spacing" error. When prompted, 3D Slicer "corrected" this by regularizing the slice spacing. However, this led to a mismatch between the slice spacing reported on MorphoSource and the spacing adjusted by 3D Slicer. Methods:To determine which slice spacing was accurate, we compared Prosthion-Basion (PR-BA) distances measured directly from physical skulls (using calipers and a Microscribe) with those derived from the CT models. We ran paired t-tests to determine whether there were differences between them. Our comparison sample included five randomly selected skulls from the error group and fifteen ramdon skulls from the error-free group (which exhibited various slice spacings when scanned). Results:For scans without the slice spacing error, there was strong agreement between physical and digital measurements, indicating metadata accuracy. For error-generating scans, measurements based on 3D Slicer's corrected spacing and Amira-Avizo both aligned well with the physical data. In contrast, manually overriding the spacing to match the MorphoSource metadata led to overestimations of the PR-BA distance. Conclusion:Although the discrepancy was straightforward to describe, resolving it required over 250 person-hours across 8 months. Accessing physical specimens, conducting repeated measurements, and cross-validating with multiple tools made the process labor-intensive. Nonetheless, this effort avoided a 3-5% measurement bias in nearly 20% of our sample and allowed inclusion of these scans in downstream semi-automated data collection. We urge researchers to thoroughly understand the digital datasets they work with and resist the temptation to ignore apparent errors during import. We also recommend that funding bodies provide support for the extensive time needed to validate and process digital imagery, both for data generators and users. Finally, we highlight the need for public repositories to implement stronger quality control. If a data import check similar to 3D Slicer's had been applied during data submission, the inconsistency between manually entered metadata and embedded DICOM information might have been caught and corrected at the time of upload.

ABSTRACT Objectives To investigate the developmental changes in the human calcaneal internal and external morphology linked to the acquisition of mature bipedal locomotion. Methods Seventy seven micro‐CT scans of modern juvenile calcanei (from perinates to 15 years old) are employed. The chronological period spans from the Middle/Late Neolithic (4800–4500 BCE) to the 20th century. Through a comprehensive approach that comprises geometric morphometric methods and whole‐bone trabecular analysis, the calcaneal growing morphology has been explored. Results Morphological changes reflect the development of bipedal locomotion, showing its potential when tracking the major locomotor milestones. The calcaneal shape is immature and almost featureless during the first year of life. The internal architecture is dense and isotropic with numerous thin trabeculae closely packed together. The internal architecture changes to better adapt to variations in load stimulated by a more mature gait by increasing bone mass and alignment, with fewer and thicker struts. The external morphology shows its plasticity by increasing the surface area where greater strain is expected and changing the orientation of the articular facets. Conclusions Analysis of morphological changes in the growing calcaneus highlights the importance of an integrative methodology when exploring developmental bone plasticity. The changes in calcaneal internal and external morphologies reflect the different loading patterns experienced during growth, gradually shifting from a more generalized morphology to a more adult‐like one, reflecting major locomotor achievement. Our research shows that although initially genetically driven, calcaneal plasticity may display mechanical influences and provide precious information on tracking the main locomotor milestones.

Globally, human population structure is quickly trending older, increasing the prevalence and systemic burden of age-related skeletal disorders such as osteoporosis. Osteoporosis is characterized by the loss of bone mass, including trabecular bone tissue, leading to skeletal fracture. Although clinically important, fundamental questions remain about normal trabecular bone variation and age-related bone loss. In this study, we use free-ranging rhesus macaques (Macaca mulatta) from the Cayo Santiago Field Station to explore variation in trabecular bone structure. We measured several aspects of trabecular bone structure (maximum and mean bone volume fraction, degree of anisotropy, and trabecular thickness) across the elbow (humerus, ulna, radius), hip (proximal femur), and knee (distal femur, tibia). Analyses of covariance models assessed factors influencing bone structure, including body mass, demography (age, sex, matriline), as well as indices of sociality and early life adversity. Point cloud models of prime and postprime age groups visualized age-related differences in bone structure. We observed significant variation in trabecular bone morphology (max and mean bone volume fraction, degree of anisotropy, and trabecular thickness) across both bones and joints. Sex influenced trabecular thickness, with thicker trabeculae in males. Max and mean bone volume fraction as well as trabecular thickness were positively associated with body mass. Age was associated with significantly lower values of mean bone volume fraction, specifically in the hind limb. We observed significant bone loss specifically in the femoral head and neck. There were no associations of trabecular bone structure with either sociality or early life adversity in this sample. This study provides a comprehensive view of trabecular bone variation by region, sex, mass, and age contextualized by social factors.

The evolution of the medial longitudinal arch (MLA) is one of the most impactful adaptations in the hominin foot that emerged with bipedalism. When and how it evolved in the human lineage is still unresolved. Complicating the issue, clinical definitions of flatfoot in living Homo sapiens have not reached a consensus. Here we digitally investigate the navicular morphology of H. sapiens (living, archaeological, and fossil), great apes, and fossil hominins and its correlation with the MLA. A distinctive navicular shape characterises living H. sapiens with adult acquired flexible flatfoot, while the congenital flexible flatfoot exhibits a ‘normal’ navicular shape. All H. sapiens groups differentiate from great apes independently from variations in the MLA, likely because of bipedalism. Most australopith, H. naledi , and H. floresiensis navicular shapes are closer to those of great apes, which is inconsistent with a human-like MLA and instead might suggest a certain degree of arboreality. Navicular shape of OH 8 and fossil H. sapiens falls within the normal living H. sapiens spectrum of variation of the MLA (including congenital flexible flatfoot and individuals with a well-developed MLA). At the same time, H. neanderthalensis seem to be characterised by a different expression of the MLA.

IntroductionThe talus plays an important role in receiving and dissipating the forces and linking the leg and the foot. As such, it is of paramount importance to analyze how its morphology, internal and external, changes during late ontogeny and through adolescence.MethodTo explore both the external shape and the internal architecture of the talus, Geometric Morphometrics and trabecular analysis have been applied to a sample of 35 tali from modern human juveniles aged between 5 and 15 years old (Middle Neolithic (4800–4500 BCE) to mid-20th century).ResultsResults show that, as the overall size of the talus increases, the shape and orientation of talar facets also change. The youngest individuals exhibit a functional talus that is still characterized by a relatively immature shape (e.g., subtly expressed margins of articular surfaces) with articular facets only minimally rotated towards an adult configuration. In adolescents, talar shape has achieved adult form after the age of 11, with all the articular facets and posterior processes well-developed. Considering internal morphology, trabecular bone varies between age classes. While Bone Volume Fraction shifts during the age 5–15 range, Degree of Anisotropy is relatively more stable over the developmental period examined in the study since it exhibits smaller variations between age classes.DiscussionThis study examined the late ontogeny of the human talus by considering both internal and external morphology. Results suggest that, although the locomotion has already assumed an adult-like pattern, the exploration of late talar growth may help understand how the talus adapts to changes in locomotor activity and how it responds to the increase in weight. Present results can be used to a better understanding of talar plasticity, improving interpretations of adult human talar form.

Objectives The study of the development of human bipedalism can provide a unique perspective on the evolution of morphology and behavior across species. To generate new knowledge of these mechanisms, we analyze changes in both internal and external morphology of the growing human talus in a sample of modern human juveniles using an innovative approach. Materials and Methods The sample consists of high-resolution microCT scans of 70 modern juvenile tali, aged between 8 postnatal weeks and 10 years old, from a broad chronological range from Middle/Late Neolithic, that is, between 4800 and 4500 BCE, to the 20th century. We applied geometric morphometric and whole-bone trabecular analysis (bone volume fraction, degree of anisotropy, trabecular number, thickness, and spacing) to all specimens to identify changes in the external and internal morphology during growth. Morphometric maps were also generated. Results During the first year of life, the talus has an immature and globular shape, with a dense, compact, and rather isotropic trabecular architecture, with numerous trabeculae packed closely together. This pattern changes while children acquire a more mature gait, and the talus tends to have a lower bone volume fraction, a higher anisotropy, and a more mature shape. Discussion The changes in talar internal and external morphologies reflect the different loading patterns experienced during growth, gradually shifting from an "unspecialized" morphology to a more complex one, following the development of bipedal gait. Our research shows that talar plasticity, even though genetically driven, may show mechanical influences and contribute to tracking the main locomotor milestones.

Trabecular bone—the spongy bone inside marrow cavities—adapts to its mechanical environment during growth and development. Trabecular structure can therefore be interpreted as a functional record of locomotor behavior in extinct vertebrates. In this paper, we expand upon traditional links between form and function by situating ontogenetic trajectories of trabecular bone in four primate species into the broader developmental context of neural development, locomotor control, and ultimately life history. Our aim is to show that trabecular bone structure provides insights into ontogenetic variation in locomotor loading conditions as the product of interactions between increases in body mass and neuromuscular maturation. Our results demonstrate that age-related changes in trabecular bone volume fraction (BV/TV) are strongly and linearly associated with ontogenetic changes in locomotor kinetics. Age-related variation in locomotor kinetics and BV/TV is in turn strongly associated with brain and body size growth in all species. These results imply that age-related variation in BV/TV is a strong proxy for both locomotor kinetics and neuromuscular maturation. Finally, we show that distinct changes in the slope of age-related variation in bone volume fraction correspond to the age of the onset of locomotion and the age of locomotor maturity. Our findings compliment previous studies linking bone development to locomotor mechanics by providing a fundamental link to brain development and life history. This implies that trabecular structure of fossil subadults can be a proxy for the rate of neuromuscular maturation and major life history events like locomotor onset and the achievement of adult-like locomotor repertoires.

The Holocene arrival of humans on Madagascar precipitated major changes to the island’s biodiversity. The now-extinct, endemic “subfossil” megafauna of Madagascar were likely hunted by the island’s early human inhabitants. Perhaps in part due to preferential hunting of larger prey, no surviving species on Madagascar is larger than 10 kg. Outside of Madagascar, size-selective hunting pressure has resulted in the phyletic dwarfism of many still-living species across a diversity of phyla. On Madagascar, some subfossil bones of extant lemurs are considerably larger than those of the modern members of their species, but relatively large distances between the subfossil localities and modern samples that have been compared to date makes it impossible to reject the possibility that these size differences more simply reflect pre-existing ecogeographic variation. Here, we used high-resolution 3D scan data to conduct comparative morphological analyses of subfossil and modern skeletal remains of one of the larger extant lemurs, Verreaux’s sifakas ( Propithecus verreauxi ) from subfossil and modern sites ∼10 km adjacent: Taolambiby (bones dated to 725-560 – 1075-955 cal. years before present) and Beza Mahafaly Special Reserve, respectively. We found that the average subfossil sifaka bone (n=12) is 9% and significantly larger than that of modern sifakas (n=31 individuals; permutation test; p=0.037). When restricting the analysis to the single element and side with the largest representation in the subfossil sample (n=4 right distal femora), the average subfossil bone is 10% larger (p=0.046). While we cannot yet conclude whether this size difference reflects evolutionary change or an archaeological aggregation/taphonomic process, if this is a case of phyletic dwarfism in response to human size-selective harvesting pressures then the estimated rate of evolutionary change is slightly higher than that previously calculated for other archaeological cases of this phenomenon.

Bone responds to mechanical loads through growth. This response to external loading has been important for understanding skeletal form and function relationships. However, uncertainty still exists regarding how different locomotor behaviors, (e.g., bipedalism, quadrupedalism) are reflected in bone morphology. This study assesses the effects of locomotor posture on femoral bone structure in a rodent model (Rattus norvegicus). The study individuals come from a previously-executed experiment (Foster, 2019) that utilized a treadmill-mounted harness to induce bipedal walking postures in rats over 12-weeks. The sample includes individuals from two experimental groups plus a control: bipedal walking, quadrupedal walking, and no exercise controls. Proximal and distal femora were microCT scanned at 20µm and trabecular bone volume fraction (BV/TV) and degree of anisotropy (DA) were analyzed and compared among groups to assess the impacts of differences in hip loading. In the proximal femur, the bipedal group had higher DA inferior to the neck and greater trochanter than the quadrupedal group, suggesting more unidirectional loading in bipeds. However, the quadrupedal group had greater BV/TV throughout the proximal metaphysis; particularly at the greater trochanter, which may be due to a higher demand for hip extension. In the distal femur, the bipedal group had higher mean BV/TV (0.39) when compared to the quadrupedal group (0.36), with a larger concentration of BV/TV in the medial condyle. These results suggest that the femoral epiphyses are responsive to changes in hip postural angle due to locomotion, however cortical bone structure and a larger sample size may be more informative.

This project aims to test whether geometric morphometric (GM) and trabecular analyses may be useful tools in identifying talar characteristics related to hypochondroplasia. We quantified the external and internal talar morphology of a hypochondroplasic dwarf (T17) from Modena (northern Italy) dated to the sixth century AD. External talar morphology of T17 was compared with a broad sample of modern human tali (n = 159) using GM methods. Additionally, a subsample of these tali (n = 41) was used to investigate whole talar trabecular changes in T17. Our results show that GM and trabecular analyses identify a combination of traits linked to the dwarfing disorder of hypochondroplasia. These traits include decreased scaled talar dimensions compared with normal-sized individuals, presence of an accessory antero-lateral talar facet, high bone volume fraction, and high anisotropy values throughout the entire talus. In our case study, hypochondroplasia does not appear to substantially modify external talar morphology probably due to the fast growth of the talus. We suggest that small talar dimensions are associated with hypochondroplasia. An antero-lateral talar facet may result from the talus and calcaneus coalition (i.e., talocalcaneal abnormal bridging) possibly related to an everted foot posture that was limited by overgrowth of the fibula. We suggest that high talar trabecular density and strut orientation provide insights into pathological development of the trabecular plates in T17. Finally, our study suggests that high talar trabecular density and strut orientation, and small talar dimensions, may be added as possible concomitant talar hallmarks for hypochondroplasia.