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1.
Proc Natl Acad Sci U S A ; 117(48): 30159-30170, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-33188087

RESUMO

Reef-building corals and their aragonite (CaCO3) skeletons support entire reef ecosystems, yet their formation mechanism is poorly understood. Here we used synchrotron spectromicroscopy to observe the nanoscale mineralogy of fresh, forming skeletons from six species spanning all reef-forming coral morphologies: Branching, encrusting, massive, and table. In all species, hydrated and anhydrous amorphous calcium carbonate nanoparticles were precursors for skeletal growth, as previously observed in a single species. The amorphous precursors here were observed in tissue, between tissue and skeleton, and at growth fronts of the skeleton, within a low-density nano- or microporous layer varying in thickness from 7 to 20 µm. Brunauer-Emmett-Teller measurements, however, indicated that the mature skeletons at the microscale were space-filling, comparable to single crystals of geologic aragonite. Nanoparticles alone can never fill space completely, thus ion-by-ion filling must be invoked to fill interstitial pores. Such ion-by-ion diffusion and attachment may occur from the supersaturated calcifying fluid known to exist in corals, or from a dense liquid precursor, observed in synthetic systems but never in biogenic ones. Concomitant particle attachment and ion-by-ion filling was previously observed in synthetic calcite rhombohedra, but never in aragonite pseudohexagonal prisms, synthetic or biogenic, as observed here. Models for biomineral growth, isotope incorporation, and coral skeletons' resilience to ocean warming and acidification must take into account the dual formation mechanism, including particle attachment and ion-by-ion space filling.


Assuntos
Antozoários/anatomia & histologia , Osso e Ossos/anatomia & histologia , Animais , Antozoários/ultraestrutura , Recifes de Corais , Íons , Modelos Anatômicos , Nanopartículas/química
2.
PLoS One ; 15(11): e0242082, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33206694

RESUMO

Modern death assemblages provide insights about the early stages of fossilization and useful ecological information about the species inhabiting the ecosystem. We present the results of taphonomic monitoring of modern vertebrate carcasses and bones from Doñana National Park, a Mediterranean coastal ecosystem in Andalusia, Spain. Ten different habitats were surveyed. Half of them occur in active depositional environments (marshland, lake margin, river margin, beach and dunes). Most of the skeletal remains belong to land mammals larger than 5 kg in body weight (mainly wild and feral ungulates). Overall, the Doñana bone assemblage shows good preservation with little damage to the bones, partly as a consequence of the low predator pressure on large vertebrates. Assemblages from active depositional habitats differ significantly from other habitats in terms of the higher incidence of breakage and chewing marks on bones in the latter, which result from scavenging, mainly by wild boar and red fox. The lake-margin and river-margin death assemblages have high concentrations of well preserved bones that are undergoing burial and offer the greatest potential to produce fossil assemblages. The spatial distribution of species in the Doñana death assemblage generally reflects the preferred habitats of the species in life. Meadows seem to be a preferred winter habitat for male deer, given the high number of shed antlers recorded there. This study is further proof that taphonomy can provide powerful insights to better understand the ecology of modern species and to infer past and future scenarios for the fossil record.


Assuntos
Fósseis/anatomia & histologia , Mamíferos/classificação , Animais , Osso e Ossos/anatomia & histologia , Demografia , Ecossistema , Mamíferos/anatomia & histologia , Paleontologia , Parques Recreativos , Espanha , Especificidade da Espécie
3.
J Vis Exp ; (163)2020 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-32955490

RESUMO

The preparation of cetacean, in particular baleen whale, skeletons presents a great challenge due to their high lipid content and uncommon size. Documentation of the skeletal morphology is important to produce accurate and reliable models for both research and educational purposes. In this paper, we used a 10.8-meter long Omura's whale stranded in Hong Kong waters in 2014 as an example for the illustration. This rare and enormous specimen was defleshed, macerated, and sun-dried to yield the skeleton for research and public display. Morphology of each bone was then documented by photogrammetry. The complex contour of the skeleton made automated photoshoot inadequate and 3 manual methods were used on bones of different sizes and shapes. The captured photos were processed to generate three-dimensional (3D) models of 166 individual bones. The skeleton was printed half-size with polylactic acid for display purposes, which was easier to maintain than the actual cetacean bones with high residual fat content. The printed bones reflected most anatomical features of the specimen, including the bowing out rostral region and the caudal condylar facet that articulated with Ce1, yet the foramina on the parieto-squamosal suture, which are diagnostic character of Balaenoptera omurai, and an indented groove on the frontal bone at the posterior end of the lateral edge were not clearly presented. Extra photoshoots or 3D surface scanning should be performed on areas with meticulous details to improve precision of the models. The electronic files of the 3D skeleton were published online to reach a global audience and facilitate scientific collaboration among researchers worldwide.


Assuntos
Osso e Ossos/anatomia & histologia , Modelos Anatômicos , Baleias/anatomia & histologia , Animais , Osso e Ossos/diagnóstico por imagem , Feminino , Hong Kong , Fotogrametria , Impressão Tridimensional
4.
PLoS One ; 15(9): e0239588, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32966345

RESUMO

Despite a growing body of evidence concerning accelerated organic degradation at archaeological sites, there have been few follow-up investigations to examine the status of the remaining archaeological materials in the ground. To address the question of archaeo-organic preservation, we revisited the Swedish, Mesolithic key-site Ageröd and could show that the bone material had been subjected to an accelerated deterioration during the last 75 years, which had destroyed the bones in the areas where they had previously been best preserved. To understand why this has happened and to quantify and qualify the extent of the organic degradation, we here analyse the soil chemistry, bone histology, collagen preservation and palaeobotany at the site. Our results show that the soil at Ageröd is losing, or has already lost, its preservative and buffering qualities, and that pH-values in the still wet areas of the site have dropped to levels where no bone preservation is possible. Our results suggest that this acidification process is enhanced by the release of sulphuric acid as pyrite in the bones oxidizes. While we are still able to find well-preserved palaeobotanical remains, they are also starting to corrode through re-introduced oxygen into the archaeological layers. While some areas of the site have been more protected through redeposited soil on top of the archaeological layers, all areas of Ageröd are rapidly deteriorating. Lastly, while it is still possible to perform molecular analyses on the best-preserved bones from the most protected areas, this opportunity will likely be lost within a few decades. In conclusion, we find that if we, as a society, wish to keep this valuable climatic, environmental and cultural archive, both at Ageröd and elsewhere, the time to act is now and if we wait we will soon be in a situation where this record will be irretrievably lost forever.


Assuntos
Arqueologia/métodos , Fósseis/história , Animais , Osso e Ossos/anatomia & histologia , Osso e Ossos/química , Botânica , Colágeno/análise , Conservação dos Recursos Naturais/métodos , Características Culturais/história , Fósseis/anatomia & histologia , História Antiga , Paleontologia , Plantas/anatomia & histologia , Preservação Biológica/história , Datação Radiométrica , Solo/química , Suécia , Áreas Alagadas
5.
J Morphol ; 281(10): 1280-1295, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32790104

RESUMO

The rheophilic hillstream loaches (Balitoridae) of South and Southeast Asia possess a range of pelvic girdle morphologies, which may be attributed to adaptations for locomotion against rapidly flowing water. Specifically, the connectivity of the pelvic plate (basipterygium) to the vertebral column via a sacral rib, and the relative size and shape of the sacral rib, fall within a spectrum of three discrete morphotypes: long, narrow rib that meets the basipterygium; thicker, slightly curved rib meeting the basipterygium; and robust crested rib interlocking with the basipterygium. Species in this third category with more robust sacral rib connections between the basipterygium and vertebral column are capable of walking out of water with a tetrapod-like lateral-sequence, diagonal-couplet gait. This behavior has not been observed in species lacking direct skeletal connection between the vertebrae and the pelvis. The phylogenetic positions of the morphotypes were visualized by matching the morphological features onto a novel hypothesis of relationships for the family Balitoridae. The morphotypes determined through skeletal morphology were correlated with patterns observed in the pelvic muscle morphology of these fishes. Transitions towards increasingly robust pelvic girdle attachment were coincident with a more anterior origin on the basipterygium and more lateral insertion of the muscles on the fin rays, along with a reduction of the superficial abductors and adductors with more posterior insertions. These modifications are expected to provide a mechanical advantage for generating force against the ground. Inclusion of the enigmatic cave-adapted balitorid Cryptotora thamicola into the most data-rich balitorid phylogeny reveals its closest relatives, providing insight into the origin of the skeletal connection between the axial skeleton and basipterygium.


Assuntos
Osso e Ossos/anatomia & histologia , Cipriniformes/anatomia & histologia , Músculos/anatomia & histologia , Pelve/anatomia & histologia , Animais , Osso e Ossos/diagnóstico por imagem , Cipriniformes/classificação , Análise de Fourier , Músculos/diagnóstico por imagem , Pelve/diagnóstico por imagem , Filogenia , Análise de Componente Principal , Microtomografia por Raio-X
7.
PLoS One ; 15(8): e0237042, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813735

RESUMO

The largest dinosaurs were enormous animals whose body mass placed massive gravitational loads on their skeleton. Previous studies investigated dinosaurian bone strength and biomechanics, but the relationships between dinosaurian trabecular bone architecture and mechanical behavior has not been studied. In this study, trabecular bone samples from the distal femur and proximal tibia of dinosaurs ranging in body mass from 23-8,000 kg were investigated. The trabecular architecture was quantified from micro-computed tomography scans and allometric scaling relationships were used to determine how the trabecular bone architectural indices changed with body mass. Trabecular bone mechanical behavior was investigated by finite element modeling. It was found that dinosaurian trabecular bone volume fraction is positively correlated with body mass similar to what is observed for extant mammalian species, while trabecular spacing, number, and connectivity density in dinosaurs is negatively correlated with body mass, exhibiting opposite behavior from extant mammals. Furthermore, it was found that trabecular bone apparent modulus is positively correlated with body mass in dinosaurian species, while no correlation was observed for mammalian species. Additionally, trabecular bone tensile and compressive principal strains were not correlated with body mass in mammalian or dinosaurian species. Trabecular bone apparent modulus was positively correlated with trabecular spacing in mammals and positively correlated with connectivity density in dinosaurs, but these differential architectural effects on trabecular bone apparent modulus limit average trabecular bone tissue strains to below 3,000 microstrain for estimated high levels of physiological loading in both mammals and dinosaurs.


Assuntos
Osso Esponjoso/anatomia & histologia , Osso Esponjoso/fisiologia , Dinossauros/anatomia & histologia , Animais , Anisotropia , Fenômenos Biomecânicos , Densidade Óssea/fisiologia , Osso e Ossos/anatomia & histologia , Força Compressiva/fisiologia , Simulação por Computador , Fêmur/anatomia & histologia , Análise de Elementos Finitos , Fósseis , Processamento de Imagem Assistida por Computador/métodos , Mamíferos/anatomia & histologia , Estresse Mecânico , Tíbia/anatomia & histologia , Microtomografia por Raio-X/métodos
8.
PLoS One ; 15(8): e0237573, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797087

RESUMO

The Late Mesolithic in Southern Europe is dated to the 7th and the first part of the 6th millennia BCE and is marked by profound changes which are mostly evident in the technical know-how and tool-kit of the last hunter-fisher-gatherer societies. The significance of this phase also relates to the fact that it precedes the Early Neolithic, another period of major transformations of human societies. Nonetheless, the Late Mesolithic still remains a poorly known age in this area. A burial discovered at Mondeval de Sora (Northern Italy) in 1987, represents a unique window into this period. In this paper, we provide a detailed analysis of more than 50 lithic and osseous artifacts associated with this burial. We highlight important contextual data regarding the techno-economic dimension and the notion of personal burial possessions. Based on the association and location of some items, we propose a new interpretation of the social status of this individual and the possible impact of technological innovation on the social organization and symbolic sphere of Late Mesolithic groups.


Assuntos
Osso e Ossos/química , Carbonato de Cálcio/análise , Lítio/análise , Magnésio/análise , Arqueologia , Osso e Ossos/anatomia & histologia , Sepultamento , Fósseis/história , História Antiga , Humanos
9.
Proc Natl Acad Sci U S A ; 117(31): 18393-18400, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32661154

RESUMO

In the past decade, the early Acheulean before 1 Mya has been a focus of active research. Acheulean lithic assemblages have been shown to extend back to ∼1.75 Mya, and considerable advances in core reduction technologies are seen by 1.5 to 1.4 Mya. Here we report a bifacially flaked bone fragment (maximum dimension ∼13 cm) of a hippopotamus femur from the ∼1.4 Mya sediments of the Konso Formation in southern Ethiopia. The large number of flake scars and their distribution pattern, together with the high frequency of cone fractures, indicate anthropogenic flaking into handaxe-like form. Use-wear analyses show quasi-continuous alternate microflake scars, wear polish, edge rounding, and striae patches along an ∼5-cm-long edge toward the handaxe tip. The striae run predominantly oblique to the edge, with some perpendicular, on both the cortical and inner faces. The combined evidence is consistent with the use of this bone artifact in longitudinal motions, such as in cutting and/or sawing. This bone handaxe is the oldest known extensively flaked example from the Early Pleistocene. Despite scarcity of well-shaped bone tools, its presence at Konso shows that sophisticated flaking was practiced by ∼1.4 Mya, not only on a range of lithic materials, but also occasionally on bone, thus expanding the documented technological repertoire of African Early Pleistocene Homo.


Assuntos
Osso e Ossos/química , Fósseis/história , Artefatos , Osso e Ossos/anatomia & histologia , Etiópia , Fósseis/anatomia & histologia , História Antiga
10.
Sci Rep ; 10(1): 10955, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32616813

RESUMO

Megamammals constituted an important component in the Pleistocene faunal communities of South America. Paleobiological and paleoecological studies involving different megamammal taxa have increased significantly in the last years, but there are still several poorly-known issues of its life history. In this work, we analyze an assemblage composed of 13 individuals of different ontogenetic stages, and possibly different sex, belonging to the giant ground sloth Lestodon armatus (Xenarthra, Folivora), recovered from Playa del Barco site (Pampean Region, Argentina). A dating of 19,849 years Cal BP allows assigning this assemblage to a period of the MIS (Marine Isotope Stage) 2 related to the end of the Last Glacial Maximum. Based on multiple lines of research (e.g. taphonomy, paleopathology, osteohistology, isotopy), we interpret the origin of the assemblage and diverse paleobiological and paleoecological aspects (e.g. social behavior, ontogenetic changes, sexual dimorphism, diseases, resource and habitat use, trophic relationships) of L. armatus. Evidence suggests that the assemblage was formed by a local single event of catastrophic mortality, which affected different members of a social group. This record represents the first accurate evidence of gregariousness for this ground sloth, providing new data on a poorly-known behavior among extinct Folivora.


Assuntos
Osso e Ossos/anatomia & histologia , Osso e Ossos/fisiologia , Cingulados/anatomia & histologia , Cingulados/fisiologia , Ecossistema , Fósseis , Animais , Argentina , Feminino , Masculino
11.
PLoS One ; 15(7): e0236272, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32716947

RESUMO

As part of an interdisciplinary research project on the Late La Tène period settlement at Basel-Gasfabrik, ceramic sherds, animal bones and archaeological sediments from different archaeological structures (one large pit, two ditches and four archaeological layers) were examined in respect of 21 taphonomic features (proxies). These proxies, in turn, were linked to different processes that can leave traces on objects or sediments: primary use, mechanical stress, heat impact, water, redeposition, exposure, covering and postdepositional processes. The different proxies were compared using a statistical procedure. Our results show significant differences between the different features with regard to taphonomic alteration. For example, ceramic sherds and animal bones from archaeological layers show severe alteration due to exposure, whilst a good and uniform preservation within the pit points to its rapid filling. Furthermore, there is evidence of middens which probably served as material depots. Our results suggest that waste was not simply seen as rubbish, but was stored as a resource. Therefore, materials could take different "paths", each of which resulted in specific taphonomic processes (alterations). The interdisciplinary approach taken in this project has provided new insight into the complex but probably clearly defined handling of various materials at Basel-Gasfabrik, thus allowing us to visualise part of the cultural biography of things.


Assuntos
Osso e Ossos/anatomia & histologia , Cerâmica , Sedimentos Geológicos/análise , Estudos Interdisciplinares , Animais , Arqueologia , Análise Fatorial , Geografia , Suíça
12.
Sci Rep ; 10(1): 9741, 2020 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-32587406

RESUMO

We describe the partial cranium and skeleton of a new diprotodontian marsupial from the late Oligocene (~26-25 Ma) Namba Formation of South Australia. This is one of the oldest Australian marsupial fossils known from an associated skeleton and it reveals previously unsuspected morphological diversity within Vombatiformes, the clade that includes wombats (Vombatidae), koalas (Phascolarctidae) and several extinct families. Several aspects of the skull and teeth of the new taxon, which we refer to a new family, are intermediate between members of the fossil family Wynyardiidae and wombats. Its postcranial skeleton exhibits features associated with scratch-digging, but it is unlikely to have been a true burrower. Body mass estimates based on postcranial dimensions range between 143 and 171 kg, suggesting that it was ~5 times larger than living wombats. Phylogenetic analysis based on 79 craniodental and 20 postcranial characters places the new taxon as sister to vombatids, with which it forms the superfamily Vombatoidea as defined here. It suggests that the highly derived vombatids evolved from wynyardiid-like ancestors, and that scratch-digging adaptations evolved in vombatoids prior to the appearance of the ever-growing (hypselodont) molars that are a characteristic feature of all post-Miocene vombatids. Ancestral state reconstructions on our preferred phylogeny suggest that bunolophodont molars are plesiomorphic for vombatiforms, with full lophodonty (characteristic of diprotodontoids) evolving from a selenodont morphology that was retained by phascolarctids and ilariids, and wynyardiids and vombatoids retaining an intermediate selenolophodont condition. There appear to have been at least six independent acquisitions of very large (>100 kg) body size within Vombatiformes, several having already occurred by the late Oligocene.


Assuntos
Evolução Biológica , Tamanho Corporal , Osso e Ossos/anatomia & histologia , Fósseis , Marsupiais/anatomia & histologia , Marsupiais/classificação , Crânio/anatomia & histologia , Animais , Filogenia , Especificidade da Espécie
13.
Proc Natl Acad Sci U S A ; 117(26): 14851-14856, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32541036

RESUMO

The Mid-Upper Paleolithic (Gravettian) karstic Grotte de Cussac (France) contains two areas of human remains in the context of abundant (and spectacular) parietal engravings. The first area (loci 1 and 2) includes the skeleton of a young adult male in a bear nest, rearranged by postdecomposition inundation, and the variably fragmentary remains of at least two individuals distributed across two bear nests, sorted anatomically and with most of the elements constrained to one side of one nest. The second area (locus 3) retains remains of two adults and an adolescent, in upper hollows and variably distributed down the slope, largely segregated into upper versus lower body groups. The only decoration associated with the human remains is red pigment on some of the bones or underlying sediment. The human remains indicate variable nonnatural deposition and manipulation of human bodies, body portions, and skeletal elements of at least six individuals. Moreover, Cussac is unusual in the association of these remains with exceptional parietal art. The complex Cussac mortuary pattern joins growing evidence from other Gravettian sites of variable treatment of individuals after death, within and across sites, in terms of formal deposition of the body versus postmortem manipulation versus surface abandonment. It provides a window onto the social diversity and the complex interactions of the living and the dead among these successful Late Pleistocene foragers.


Assuntos
Sepultamento/história , Adulto , Animais , Arqueologia , Osso e Ossos/anatomia & histologia , Cavernas , França , História Antiga , Humanos , Masculino , Adulto Jovem
14.
J Morphol ; 281(8): 956-969, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32557795

RESUMO

What is the functional effect of prolonged development? By controlling for size, we quantify first-feeding performance and hydrodynamics of zebrafish and guppy offspring (5 ± 0.5 mm in length), which differ fivefold in developmental time and twofold in ontogenetic state. By manipulating water viscosity, we control the hydrodynamic regime, measured as Reynolds number. We predicted that if feeding performance were strictly the result of hydrodynamics, and not development, feeding performance would scale with Reynolds number. We find that guppy offspring successfully feed at much greater distances to prey (1.0 vs. 0.2 mm) and with higher capture success (90 vs. 20%) compared with zebrafish larvae, and that feeding performance was not a result of Reynolds number alone. Flow visualization shows that zebrafish larvae produce a bow wave ~0.2 mm in length, and that the flow field produced during suction does not extend beyond this bow wave. Due to well-developed oral jaw protrusion, the similar-sized suction field generated by guppy offspring extends beyond the horizon of their bow wave, leading to successful prey capture from greater distances. These findings suggest that prolonged development and increased ontogenetic state provides first-feeding fish time to escape the pervasive hydrodynamic constraints (bow wave) of being small.


Assuntos
Comportamento Alimentar/fisiologia , Hidrodinâmica , Peixe-Zebra/crescimento & desenvolvimento , Animais , Fenômenos Biomecânicos , Osso e Ossos/anatomia & histologia , Feminino , Larva/crescimento & desenvolvimento , Masculino , Modelos Biológicos , Comportamento Predatório , Fatores de Tempo , Viscosidade
15.
PLoS One ; 15(6): e0233377, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32502155

RESUMO

The biology of how faces are built and come to differ from one another is complex. Discovering normal variants that contribute to differences in facial morphology is one key to untangling this complexity, with important implications for medicine and evolutionary biology. This study maps quantitative trait loci (QTL) for skeletal facial shape using Diversity Outbred (DO) mice. The DO is a randomly outcrossed population with high heterozygosity that captures the allelic diversity of eight inbred mouse lines from three subspecies. The study uses a sample of 1147 DO animals (the largest sample yet employed for a shape QTL study in mouse), each characterized by 22 three-dimensional landmarks, 56,885 autosomal and X-chromosome markers, and sex and age classifiers. We identified 37 facial shape QTL across 20 shape principal components (PCs) using a mixed effects regression that accounts for kinship among observations. The QTL include some previously identified intervals as well as new regions that expand the list of potential targets for future experimental study. Three QTL characterized shape associations with size (allometry). Median support interval size was 3.5 Mb. Narrowing additional analysis to QTL for the five largest magnitude shape PCs, we found significant overrepresentation of genes with known roles in growth, skeletal and facial development, and sensory organ development. For most intervals, one or more of these genes lies within 0.25 Mb of the QTL's peak. QTL effect sizes were small, with none explaining more than 0.5% of facial shape variation. Thus, our results are consistent with a model of facial diversity that is influenced by key genes in skeletal and facial development and, simultaneously, is highly polygenic.


Assuntos
Desenvolvimento Ósseo/genética , Ossos Faciais/anatomia & histologia , Desenvolvimento Maxilofacial/genética , Alelos , Animais , Osso e Ossos/anatomia & histologia , Mapeamento Cromossômico/métodos , Camundongos de Cruzamento Colaborativo/genética , Face/anatomia & histologia , Feminino , Variação Genética/genética , Genótipo , Masculino , Camundongos , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Locos de Características Quantitativas/genética
16.
J Morphol ; 281(7): 754-764, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32427377

RESUMO

Madagascar's endemic ground-dwelling leaf chameleons (Brookesiinae: Brookesia Gray, 1865 + Palleon Glaw, et al., Salamandra, 2013, 49, pp. 237-238) form the sister taxon to all other chameleons (i.e., the Chamaeleoninae). They possess a limited ability of color change, a rather dull coloration, and a nonprehensile tail assisting locomotion in the leaf litter on the forest floor. Most Brookesia species can readily be recognized by peculiar spiky dorsolateral projections ("Rückensäge"), which are caused by an aberrant vertebral structure and might function as body armor to prevent predation. In addition to a pronounced Rückensäge, the Antsingy leaf chameleon Brookesia perarmata (Angel, 1933) exhibits conspicuous, acuminate tubercle scales on the lateral flanks and extremities, thereby considerably enhancing the overall armored appearance. Such structures are exceptional within the Chamaeleonidae and despite an appreciable interest in the integument of chameleons in general, the morphology of these integumentary elements remains shrouded in mystery. Using various conventional and petrographic histological approaches combined with µCT-imaging, we reveal that the tubercle scales consist of osseous, multicusped cores that are embedded within the dermis. Based on this, they consequently can be interpreted as osteoderms, which to the best of our knowledge is the first record of such for the entire Chamaeleonidae and only the second one for the entire clade Iguania. The combination of certain aspects of tissue composition (especially the presence of large, interconnected, and marrow-filled cavities) together with the precise location within the dermis (being completely enveloped by the stratum superficiale), however, discriminate the osteoderms of B. perarmata from those known for all other lepidosaurs.


Assuntos
Osso e Ossos/anatomia & histologia , Osso e Ossos/diagnóstico por imagem , Lagartos/anatomia & histologia , Pele/anatomia & histologia , Pele/diagnóstico por imagem , Microtomografia por Raio-X , Animais , Imageamento Tridimensional , Coluna Vertebral/anatomia & histologia , Coluna Vertebral/citologia
17.
Sports Health ; 12(5): 431-440, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32442050

RESUMO

BACKGROUND: The positive association between physical fitness and bone structure has been widely investigated in children and adolescents, yet no studies have evaluated this influence in young children (ie, preschoolers). HYPOTHESIS: Fit children will present improved bone variables when compared with unfit children, and no sex-based differences will emerge in the sample. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Handgrip strength, standing long jump (SLJ), speed/agility, balance, and cardiorespiratory fitness (CRF) were assessed using the Assessing FITness levels in PREschoolers (PREFIT) test battery in 92 children (50 boys; age range, 3-5 years). A peripheral quantitative computed tomography scan was performed at 38% of the length of the nondominant tibia. Cluster analysis from handgrip strength, SLJ, speed/agility, and CRF was developed to identify fitness groups. Bone variables were compared between sexes and between cluster groups. The association between individual physical fitness components and different bone variables was also tested. RESULTS: Three cluster groups emerged: fit (high values on all included physical fitness variables), strong (high strength values and low speed/agility and CRF), and unfit (low strength, speed/agility, and CRF). The fit group presented higher values than the strong and unfit groups for total and cortical bone mineral content, cortical area, and polar strength strain index (all P < 0.05). The fit group also presented a higher cortical thickness when compared with the unfit group (P < 0.05). Handgrip, SLJ, and speed/agility predicted all bone variables except for total and cortical volumetric bone mineral density. No differences were found for bone variables between sexes. CONCLUSION: The results suggest that global fitness in preschoolers is a key determinant for bone structure and strength but not volumetric bone mineral density. CLINICAL RELEVANCE: Physical fitness is a determinant for tibial bone mineral content, structure, and strength in very young children. Performing physical fitness tests could provide useful information related to bone health in preschoolers.


Assuntos
Osso e Ossos/anatomia & histologia , Osso e Ossos/fisiologia , Aptidão Física/fisiologia , Caracteres Sexuais , Densidade Óssea/fisiologia , Aptidão Cardiorrespiratória/fisiologia , Pré-Escolar , Análise por Conglomerados , Estudos Transversais , Teste de Esforço/métodos , Feminino , Força da Mão/fisiologia , Humanos , Extremidade Inferior/fisiologia , Masculino , Estudos Retrospectivos , Tíbia/fisiologia
18.
PLoS One ; 15(3): e0230642, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32226040

RESUMO

Evidence for specialised bone tools has recently been reported for the Middle Stone Age of North Africa [one], which complements similar finds of slightly younger age in South Africa [two, three]. However, until now scant reference has been made to lesser known tools also made of bone ('bone retouchers') that were employed specifically as intermediaries for working or refining stone artefacts, that are sometimes present in these assemblages. In this paper we describe 20 bone retouchers from the cave of Grotte des Pigeons at Taforalt in north-east Morocco. This is the largest stratified assemblage of bone retouchers from a North African MSA site, and the biggest single collection so far from the African Continent. A total of 18 bone retouchers was recovered in securely dated archaeological levels spanning a period from ~ 84.5 ka to 24 ka cal BP. A further two bone retouchers were found in a layer at the base of the deposits in association with Aterian artefacts dating to around 85,000 BP and so far represent the earliest evidence of this type of tool at Taforalt. In this paper we present a first, detailed description of the finds and trace the stages of their production, use and discard (chaîne opératoire). At the same time, we assess if there were diachronic changes in their form and function and, finally, explore their presence in relation to stone tools from the same occupation layers of the cave.


Assuntos
Osso e Ossos/anatomia & histologia , Fósseis/história , Tecnologia , Arqueologia , História Antiga , Humanos , Marrocos
19.
Actual. osteol ; 16(1): 47-66, Ene - abr. 2020. ilus
Artigo em Espanhol | LILACS | ID: biblio-1140035

RESUMO

La "razón de ser" de nuestros huesos y esqueletos constituye un dilema centralizado en los conceptos biológicos de "estructura" y "organización", cuya solución necesitamos comprender para interpretar, diagnosticar, tratar y monitorear correctamente las osteopatías fragilizantes. Últimamente se ha reunido conocimiento suficiente para proponer aproximaciones razonables a ese objetivo. La que exponemos aquí requiere la aplicación de no menos de 6 criterios congruentes: 1) Un criterio cosmológico, que propone un origen común para todas las cosas; 2) Un criterio biológico, que explica el origen común de todos los huesos; 3) Un enfoque epistemológico, que desafía nuestra capacidad de comprensión del concepto concreto de estructura y del concepto abstracto de organización, focalizada en la noción rectora de direccionalidad espacial; 4) Una visión ecológica, que destaca la importancia del entorno mecánico de cada organismo para la adecuación de la calidad mecánica de sus huesos a las "funciones de sostén" que les adjudicamos; 5) Una correlación entre todo ese conocimiento y el necesario para optimizar nuestra aptitud para resolver los problemas clínicos implicados y 6) Una jerarquización del papel celular en el manejo de las interacciones genético-ambientales necesario para asimilar todo el problema a una simple cuestión de organización direccional de la estructura de cada hueso. Solo aplicando estos 6 criterios estaríamos en condiciones de responder a la incógnita planteada por el título. La conclusión de esta interpretación de la conducta y función de los huesos debería afectar el fundamento de la mayoría de las indicaciones farmacológicas destinadas al tratamiento de la fragilidad ósea. (AU)


The nature of the general behavior of our bones as weight-bearing structures is a matter of two biological concepts, namely, structure and organization, which are relevant to properly interpret, diagnose, treat, and monitor all boneweakening diseases. Different approaches can be proposed to trace the corresponding relationships. The one we present here involves six congruent criteria, namely, 1) a cosmological proposal of a common origin for everything; 2) a biological acknowledgement of a common origin for all bones; 3) the epistemological questioning of our understanding of the concrete concept of structure and the abstract notion of organization, focused on the lead idea of directionality; 4) the ecological insight that emphasizes the relevance of the mechanical environment of every organism to the naturally-selected adjustment of the mechanical properties of their mobile bones to act as struts or levers; 5) The clinical aspects of all the alluded associations; 6) The central role of bone cells to control the genetics/ environment interactions of any individual as needed to optimize the directionality of the structure of each of his/her bones to keep their mechanical ability within physiological limits. From our point of view, we could only solve the riddle posed by the title by addressing all of these six criteria. The striking conclusion of our analysis suggests that the structure (not the mass) of every bone would be controlled not only to take care of its mechanical ability, but also to cope with other properties which show a higher priority concerning natural selection. The matter would be that this interpretation of bone behavior and 'function' should affect the rationales for most pharmacological indications currently made to take care of bone fragility. (AU)


Assuntos
Humanos , Osso e Ossos/fisiologia , Doenças Ósseas Metabólicas/diagnóstico , Osteogênese Imperfeita/diagnóstico , Osteogênese Imperfeita/terapia , Osteoporose/diagnóstico , Osteoporose/terapia , Osso e Ossos/anatomia & histologia , Osso e Ossos/citologia , Osso e Ossos/ultraestrutura , Doenças Ósseas Metabólicas/terapia , Epigênese Genética
20.
PLoS One ; 15(4): e0230440, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236122

RESUMO

Immature remains are critical for understanding maturational processes in hominin species as well as for interpreting changes in ontogenetic development in hominin evolution. The study of these subjects is hindered by the fact that associated juvenile remains are extremely rare in the hominin fossil record. Here we describe an assemblage of immature remains of Homo naledi recovered from the 2013-2014 excavation season. From this assemblage, we attribute 16 postcranial elements and a partial mandible with some dentition to a single juvenile Homo naledi individual. The find includes postcranial elements never before discovered as immature elements in the sub-equatorial early hominin fossil record, and contributes new data to the field of hominin ontogeny.


Assuntos
Osso e Ossos/anatomia & histologia , Fósseis/anatomia & histologia , Mandíbula/anatomia & histologia , Animais , Evolução Biológica , Hominidae , África do Sul
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