First osteohistological and histotaphonomic approach of Equus occidentalis Leidy, 1865 (Mammalia, Equidae) from the late Pleistocene of Rancho La Brea (California, USA)

Rancho La Brea (California, USA) is the most emblematic Quaternary fossiliferous locality in the world, since both the high number and diversity of the specimens recovered and their excellent preservational quality. In the last decades, paleobiological and paleoecological knowledge of the different groups of mammals from this site has increased notably; however, some aspects have not yet been inquired or there is little information. In this work we provide information on one of the most abundant mammals of this site, the equid Equus occidentalis, based on the study, from osteohistological and histotaphonomic perspectives, of thin sections of different limb bones. On the one hand, from an osteohistological viewpoint, we observe that the distribution and characterization of bone tissues in the different skeletal elements are, in general lines, similar to that mentioned for other extant and extinct equids. Cyclical growth marks allowed us to propose preliminary skeletochronological interpretations. On the other hand, from a taphonomic viewpoint, we note that all the samples reflect an excellent preservation of the bone microstructure, slightly altered by different pre- and post-burial processes. The variations recorded evidence different taphonomic history and preservation conditions among pits. This is the first study including fossil material from Rancho La Brea exclusively based on the analysis of the bone microstructure features.

The Stegodon Bonebed of the Middle Pleistocene Archaeological Site Mata Menge (Flores, Indonesia): Taphonomic Agents in Site Formation

The Middle Pleistocene fluvial channel site of the Upper Fossil-bearing Interval at Mata Menge in the So’a Basin, Flores, Indonesia, has yielded the earliest fossil evidence for Homo floresiensis in association with stone artefacts and fossils of highly endemic insular fauna, including Stegodon, giant rats, crocodiles, Komodo dragons, and various birds. A preliminary taphonomic review of the fossil material here aimed to provide additional context for the hominin remains in this bonebed. Analysis was performed on two subsets of material from the same fluvial sandstone layer. Subset 1 comprised all material from two adjacent one-metre square quadrants (n = 91), and Subset 2 all Stegodon long limb bones excavated from the same layer (n = 17). Key analytical parameters included species and skeletal element identification; fossil size measurements and fragmentation; weathering stages; bone fracture characteristics; and other biological and geological bone surface modifications. Analysis of Subset 1 material identified a highly fragmented assemblage with a significant bias towards Stegodon. A large portion of these bones were likely fractured by trampling prior to entering the fluvial channel and were transported away from the death-site, undergoing surface modification causing rounding. Subset 2 material was less likely to have been transported far based on its limited susceptibility to fluvial transport. There was no significant difference in weathering for the long limb bones and fragments, with the highest portion exhibiting Stage 2 weathering, indicating that prior to final burial, all material was exposed to prolonged periods of surface exposure. Approximately 10% of all material have characteristics of fracturing on fresh bone, contributing to the taphonomic context for this bonebed; however insufficient evidence was found for anthropogenic modification.

COMBINED INJURY OF THE BREAST AND ABDOMINAL IN PEDESTRIANS INJURED BY AUTOMOTIVE INJURY

Purpose of the study. Revealing the features of the formation of damage to the structure of the chest and abdominal organs in pedestrians during their collisions with moving cars. Materials and methods. A forensic medical examination of 215 corpses of persons killed in collisions with moving cars was carried out. Among the dead there were 173 men and 42 women. The victims were between 14 and 75 years old. Research results and their discussion. It was found that among pedestrians who died in collisions with cars, injuries of two or more parts of the body with fractures of the limb bones (55.8%) and сombined injury (CI) of the head, chest, abdomen (23.3%) prevail. In the composition of CI, damage to the structure of the chest and organs of the chest cavity was noted in 85.6% of cases. Rib fractures were detected in 57.7% of cases; fractures in the midclavicular and axillary lines predominated in localization. Damage to the structure of organs and tissues of the abdominal cavity in the composition of the abdominal CI in pedestrians was -71.0%. At the same time, 80.8% of the dead pedestrians show signs of injury to organs and tissues with pronounced hemorrhages in the suspension apparatuses, walls and parenchyma of organs. In 23.2% of cases, along with hemorrhages, there is a violation of the anatomical integrity of organs, mainly the liver and spleen. The outlined nature of damage to the structure of the chest, organs of the chest and abdominal cavity made it possible to establish the possibility of their formation in the 3rd phase of car injury - the fall of the injured on the road surface. Traumatic (pleuropulmonary), hemorrhagic shock and hemorrhagic pneumothorax were the main causes of injuries at the prehospital stage.

The Skeleton of Giraffes

The giraffe skeleton consists of ~170 bones. The dry mass of the skeleton is 70 g.kg-1 body mass. The average chemical composition of their bones is 33% minerals (mainly calcium and phosphorus in a ratio of 2:1), 34% collagen, and 33% water. The skull contributes ~10%, the vertebrae ~25% and the limb bones ~65% to skeleton mass. The average density of all bones is 1.6 g cm-3, ranging from 0.8 g cm-3 (cervical vertebrae) to 2.0 g cm-3 (limb bones). Resistance to fracture by vertebrae depends on their cross-sectional area, and is greatest in cervical and the first few thoracic vertebrae. Resistance to fracture by limb bones depends on wall thickness (the difference between inner and outer diameter), which is uniquely thick. The growth of all limb bones except the humerus follows a geometric pattern (length and diameter increase at the same rate) which confers resistance to compression stress. The humerus follows an elastic pattern (diameter increases faster than length) a pattern that resists bending stress. Giraffes bones are exceptionally straight which further reduces bending stresses. The torque generated by the mass of the head and neck is resisted by the ligamentum nuchae which is exceptionally well-developed in giraffes, extends from the lumbar vertebrae to the occipital crest, can have a diameter of ~10 cm, and can support loads of ~1.8 tonnes before rupturing. As a giraffe grows muscle cross-sectional area (and contraction strength) declines and the duty factor reduces, both of which reduce the risk of fracture.

A highly conserved ontogenetic limb allometry and its evolutionary significance in the adaptive radiation of Anolis lizards

Diversifications often proceed along highly conserved, evolutionary trajectories. These patterns of covariation arise in ontogeny, which raises the possibility that adaptive morphologies are biased towards trait covariations that resemble growth trajectories. Here, we test this prediction in the diverse clade of Anolis lizards by investigating the covariation of embryonic growth of 13 fore- and hindlimb bones in 15 species, and compare these to the evolutionary covariation of these limb bones across 267 Anolis species. Our results demonstrate that species differences in relative limb length are established already at hatching, and are resulting from both differential growth and differential sizes of cartilaginous anlagen. Multivariate analysis revealed that Antillean Anolis share a common ontogenetic allometry that is characterized by positive allometric growth of the long bones relative to metapodial and phalangeal bones. This major axis of ontogenetic allometry in limb bones deviated from the major axis of evolutionary allometry of the Antillean Anolis and the two clades of mainland Anolis lizards. These results demonstrate that the remarkable diversification of locomotor specialists in Anolis lizards are accessible through changes that are largely independent from ontogenetic growth trajectories, and therefore likely to be the result of modifications that manifest at the earliest stages of limb development.

БИЛАТЕРАЛЬНАЯ АСИММЕТРИЯ ДЛИННЫХ КОСТЕЙ СКЕЛЕТА У ТОБОЛО-ИРТЫШСКИХ ТАТАР

В статье представлены результаты изучения билатеральной асимметрии длинных костей скелета у четырёх групп тоболо-иртышских татар: аялынских, тобольских, тюменских и коурдакско-саргатских татар. Для каждой группы мужчин и женщин была рассчитаны коэффициенты асимметрии (использовалась формула R–L), процентное соотношение которых показывает, что наиболее симметричная скелетная система у аялынских татар, а самая асимметричная у коурдакско-саргатских татар. При анализе коэффициентов асимметрии отдельных костей, было выявлено, что во всех исследуемых группах у мужчин и женщин самой асимметричной костью является плечевая кость. Анализ коэффициентов асимметрии по отдельным признакам показал, что во всех группах наибольшей асимметрией отличаются продольные диаметры костей верхних конечностей. Левосторонняя асимметрия в группах тоболо-иртышских татар в основном характерна для признаков костей нижних конечностей как у мужчин, так и у женщин. Закономерности в половом распределении коэффициентов асимметрии в группах тоболо-иртышских татар выявлены не были. Для наглядности изменчивости коэффициентов асимметрии для мужских и женских групп тоболо-иртышских татар были построены комбинационные полигоны, форма которых показала, что наиболее схожи между собой мужчины тобольских и коурдакско-саргатских татар, а аялынские и тюменские татары заметно отличаются как от этих групп, так и между собой. Формы комбинационных полигонов женских серий тоболо-иртышских татар не обнаруживают видимого сходства между собой. Таким образом, выявленные различия в асимметрии скелетной системы этно-территориальных групп тоболо-иртышских татар, возможно, связаны с хозяйственным укладом жизни татар, который, ввиду различной территории расселения тех или иных этно-территориальных групп, заметно отличался. The article presents the results of studying the limb bone bilateral asymmetry in four groups of the Tobol-Irtysh Tatars: Ayalyn, Tobolsk, Tyumen and Kourdak-Sargat Tatars. The asymmetry coefficients were calculated for the male and female samples of each group (using the R – L formula). The Ayalyn Tatars resulted to have the most symmetric skeletal system, while the Kourdak-Sargat Tatars – the least symmetrical one. The analysis of the asymmetry coefficients of individual bones revealed that the humerus is the most asymmetric bone in both sexes among all the studied groups. The lengths of the upper limb bones resulted to be the most asymmetrical measurement in all groups. Left-sided asymmetry was mainly seen in the lower limb bones among the Tobol-Irtysh Tatars. No sex differences in the asymmetry coefficients were revealed. Combination polygons were produced to illustrate the variability of the asymmetry coefficients for the male and female samples. Male samples of the Tobolsk and Kourdak-Sargat Tatars were found to be most similar to each other, and the Ayalyn and Tyumen Tatars are noticeably different both from these groups and from each other. The combination polygons of the female samples of the Tobol-Irtysh Tatars do not reveal any visible similarity between them. Thus, the revealed differences in the asymmetry of the skeletal system of the Tobol-Irtysh Tatars ethno-territorial groups are possibly associated with different economy systems of the groups.

Locomotory behaviour of early tetrapods from Blue Beach, Nova Scotia, revealed by novel microanatomical analysis

Evidence for terrestriality in early tetrapods is fundamentally contradictory. Fossil trackways attributed to early terrestrial tetrapods long predate the first body fossils from the Late Devonian. However, the Devonian body fossils demonstrate an obligatorily aquatic lifestyle. Complicating our understanding of the transition from water to land is a pronounced gap in the fossil record between the aquatic Devonian taxa and presumably terrestrial tetrapods from the later Early Carboniferous. Recent work suggests that an obligatorily aquatic habit persists much higher in the tetrapod tree than previously recognized. Here, we present independent microanatomical data of locomotor capability from the earliest Carboniferous of Blue Beach, Nova Scotia. The site preserves limb bones from taxa representative of Late Devonian to mid-Carboniferous faunas as well as a rich trackway record. Given that bone remodels in response to functional stresses including gravity and ground reaction forces, we analysed both the midshaft compactness profiles and trabecular anisotropy, the latter using a new whole bone approach. Our findings suggest that early tetrapods retained an aquatic lifestyle despite varied limb morphologies, prior to their emergence onto land. These results suggest that trackways attributed to early tetrapods be closely scrutinized for additional information regarding their creation conditions, and demand an expansion of sampling to better identify the first terrestrial tetrapods.

Age-related changes of the histological structure in the limb bones of the domestic fowl

To assess the possibility of using the bird bone tissue as a recording structure, the histomorphological parameters of the bone tissue of laying hens of the lohman brown cross from the Kirov region (9 females and 1 male) aged from 1 month to 7.5 years were investigated. The comparison of the cross-sections of the humerus and femur, the phalanx of the toe and tibiotarsus of a 6-year-old individual revealed that tibiotarsus is the least susceptible to resorption. For further research in 7 individuals, this bone was divided into 3 sections (T1, T2 and T3), for each of which the description and measurement of the microstructure of the cross sections was carried out. It was revealed that the process of resorption of the periosteum begins at 2.5 years of age with the appearance of primary osteons. At the age of 3.5 years and later they penetrate into all layers of the periosteum, locating in chains between the lines of arrested growth. At 4.5 years of age, secondary osteons appear in the place of the primary ones, and areas of resorption are formed at the intersection of the Haversian and Volkmann canals. At the age of 5.5 years the medullary bone disappears from the bone cavity, rounded cavities filled with centripetal deposition of new bone tissue at the edges appear within the resorption sites. At the age of 6-7 years, bone tissue degeneration occurs, when the small cavities enlarge and merge into large resorption cavities, up to the complete resorption of the mesost. In the distal part of tibiotarsus (T3), a prolonged apposition of the layers of the periosteum and the latest resorption were recorded. The increase of the thickness of the periosteum and a decrease in the density of the osteon population was revealed by the morphometry of cross sections of the center of diaphysis. The sites of tibiotarsus where the age of females corresponds to the lines of growth layer of the periosteum were determined. The sites with additional lines of the arrested growth were demarcated. It was concluded that the periosteal layer of the domestic fowl tibiotarsus in the distal and proximal sites are suitable as a recording structure.