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Abstract
Joints enable nearly all vertebrate animal motion, from feeding to locomotion. However, despite well over a century of arthrological research, we still understand very little about how the structure of joints relates to the kinematics they exhibit in life. This Commentary discusses the value of joint mobility as a lens through which to study articular form and function. By independently exploring form-mobility and mobility-function relationships and integrating the insights gained, we can develop a deep understanding of the strength and causality of articular form-function relationships. In turn, we will better illuminate the basics of 'how joints work' and be well positioned to tackle comparative investigations of the diverse repertoire of vertebrate animal motion.
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Affiliation(s)
- Armita R Manafzadeh
- Yale Institute for Biospheric Studies, Yale University, New Haven, CT 06520, USA.,Department of Earth & Planetary Sciences, Yale University, New Haven, CT 06520-8109, USA.,Yale Peabody Museum of Natural History, 170 Whitney Avenue, New Haven, CT 06520, USA.,Department of Mechanical Engineering and Materials Science, Yale University, 17 Hillhouse Avenue, New Haven, CT 06520-8292, USA
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2
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Scheidt A, Ditzel PC, Geiger SM, Wagner FC, Mülling CKW, Nyakatura JA. A therian mammal with sprawling kinematics? Gait and 3D forelimb X-ray motion analysis in tamanduas. J Exp Biol 2022; 225:275397. [PMID: 35554550 DOI: 10.1242/jeb.243625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/08/2022] [Indexed: 10/18/2022]
Abstract
Therian mammals are known to move their forelimbs in a parasagittal plane, retracting the mobilised scapula during stance phase. Non-cursorial therian mammals often abduct the elbow out of the shoulder-hip parasagittal plane. This is especially prominent in Tamandua (Xenarthra), which suggests they employ aspects of sprawling (e.g., lizard-like-) locomotion. Here, we test if tamanduas use sprawling forelimb kinematics, i.e., a largely immobile scapula with pronounced lateral spine bending and long-axis rotation of the humerus. We analyse high speed videos and use X-ray motion analysis of tamanduas walking and balancing on branches of varying inclinations and provide a quantitative characterization of gaits and forelimb kinematics. Tamanduas displayed lateral sequence lateral-couplets gaits on flat ground and horizontal branches, but increased diagonality on steeper in- and declines, resulting in lateral sequence diagonal-couplets gaits. This result provides further evidence for high diagonality in arboreal species, likely maximising stability in arboreal environments. Further, the results reveal a mosaic of sprawling and parasagittal kinematic characteristics. The abducted elbow results from a constantly internally rotated scapula about its long axis and a retracted humerus. Scapula retraction contributes considerably to stride length. However, lateral rotation in the pectoral region of the spine (range: 21°) is higher than reported for other therian mammals. Instead, it is similar to skinks and alligators, indicating an aspect generally associated with sprawling locomotion is characteristic for forelimb kinematics of tamanduas. Our study contributes to a growing body of evidence of highly variable non-cursorial therian mammal locomotor kinematics.
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Affiliation(s)
- Adrian Scheidt
- AG Vergleichende Zoologie, Institut für Biologie, Humboldt Universität zu Berlin, Philippstraße 13, 10115 Berlin, Germany
| | - Paulo C Ditzel
- AG Vergleichende Zoologie, Institut für Biologie, Humboldt Universität zu Berlin, Philippstraße 13, 10115 Berlin, Germany
| | - Sandra M Geiger
- Institute of Veterinary Anatomy, Histology and Embryology, Leipzig University, An den Tierkliniken 43, 04103 Leipzig, Germany
| | - Franziska C Wagner
- Institute of Veterinary Anatomy, Histology and Embryology, Leipzig University, An den Tierkliniken 43, 04103 Leipzig, Germany
| | - Christoph K W Mülling
- Institute of Veterinary Anatomy, Histology and Embryology, Leipzig University, An den Tierkliniken 43, 04103 Leipzig, Germany
| | - John A Nyakatura
- AG Vergleichende Zoologie, Institut für Biologie, Humboldt Universität zu Berlin, Philippstraße 13, 10115 Berlin, Germany
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3
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Oliver JD, Jones KE, Pierce SE, Hautier L. Size and shape regional differentiation during the development of the spine in the nine-banded armadillo (Dasypus novemcinctus). Evol Dev 2021; 23:496-512. [PMID: 34813149 DOI: 10.1111/ede.12393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 11/28/2022]
Abstract
Xenarthrans (armadillos, anteaters, sloths, and their extinct relatives) are unique among mammals in displaying a distinctive specialization of the posterior trunk vertebrae-supernumerary vertebral xenarthrous articulations. This study seeks to understand how xenarthry develops through ontogeny and if it may be constrained to appear within pre-existing vertebral regions. Using three-dimensional geometric morphometrics on the neural arches of vertebrae, we explore phenotypic, allometric, and disparity patterns of the different axial morphotypes during the ontogeny of nine-banded armadillos. Shape-based regionalization analyses showed that the adult thoracolumbar column is divided into three regions according to the presence or absence of ribs and the presence or absence of xenarthrous articulations. A three-region division was retrieved in almost all specimens through development, although younger stages (e.g., fetuses, neonates) have more region boundary variability. In size-based regionalization analyses, thoracolumbar vertebrae are separated into two regions: a prediaphragmatic, prexenarthrous region, and a postdiaphragmatic xenarthrous region. We show that posterior thoracic vertebrae grow at a slower rate, while anterior thoracics and lumbars grow at a faster rate relatively, with rates decreasing anteroposteriorly in the former and increasing anteroposteriorly in the latter. We propose that different proportions between vertebrae and vertebral regions might result from differences in growth pattern and timing of ossification.
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Affiliation(s)
- Jillian D Oliver
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA
| | - Katrina E Jones
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA
| | - Stephanie E Pierce
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA
| | - Lionel Hautier
- Institut des Sciences de l'Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier, France
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4
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Zack EH, Smith SM, Angielczyk KD. Effect of captivity on the vertebral bone microstructure of xenarthran mammals. Anat Rec (Hoboken) 2021; 305:1611-1628. [PMID: 34677912 DOI: 10.1002/ar.24817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/29/2022]
Abstract
Captive specimens in museum collections facilitate study of rare taxa, but the lifestyles, diets, and lifespans of captive animals differ from their wild counterparts. Trabecular bone architecture adapts to in vivo forces, and may reflect interspecific variation in ecology and behavior as well as intraspecific variation between captive and wild specimens. We compared trunk vertebrae bone microstructure in captive and wild xenarthran mammals to test the effects of ecology and captivity. We collected μCT scans of the last six presacral vertebrae in 13 fossorial, terrestrial, and suspensorial xenarthran species (body mass: 120 g to 35 kg). For each vertebra, we measured centrum length; bone volume fraction (BV.TV); trabecular number and mean thickness (Tb.Th); global compactness (GC); cross-sectional area; mean intercept length; star length distribution; and connectivity and connectivity density. Wild specimens have more robust trabeculae, but this varies with species, ecology, and pathology. Wild specimens of fossorial taxa (Dasypus) have more robust trabeculae than captives, but there is no clear difference in bone microstructure between wild and captive specimens of suspensorial taxa (Bradypus, Choloepus), suggesting that locomotor ecology influences the degree to which captivity affects bone microstructure. Captive Tamandua and Myrmecophaga have higher BV.TV, Tb.Th, and GC than their wild counterparts due to captivity-caused bone pathologies. Our results add to the understanding of variation in mammalian bone microstructure, suggest caution when including captive specimens in bone microstructure research, and indicate the need to better replicate the habitats, diets, and behavior of animals in captivity.
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Affiliation(s)
- Ellianna H Zack
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, USA
| | - Stephanie M Smith
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, USA
| | - Kenneth D Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, USA
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5
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Jones KE, Brocklehurst RJ, Pierce SE. AutoBend: An Automated Approach for Estimating Intervertebral Joint Function from Bone-Only Digital Models. Integr Org Biol 2021; 3:obab026. [PMID: 34661062 PMCID: PMC8514422 DOI: 10.1093/iob/obab026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/06/2021] [Accepted: 09/08/2021] [Indexed: 11/16/2022] Open
Abstract
Deciphering the biological function of rare or extinct species is key to understanding evolutionary patterns across the tree of life. While soft tissues are vital determinants of joint function, they are rarely available for study. Therefore, extracting functional signals from skeletons, which are more widely available via museum collections, has become a priority for the field of comparative biomechanics. While most work has focused on the limb skeleton, the axial skeleton plays a critical role in body support, respiration, and locomotion, and is therefore of central importance for understanding broad-scale functional evolution. Here, we describe and experimentally validate AutoBend, an automated approach to estimating intervertebral joint function from bony vertebral columns. AutoBend calculates osteological range of motion (oROM) by automatically manipulating digitally articulated vertebrae while incorporating multiple constraints on motion, including both bony intersection and the role of soft tissues by restricting excessive strain in both centrum and zygapophyseal articulations. Using AutoBend and biomechanical data from cadaveric experiments on cats and tegus, we validate important modeling parameters required for oROM estimation, including the degree of zygapophyseal disarticulation, and the location of the center of rotation. Based on our validation, we apply a model with the center of rotation located within the vertebral disk, no joint translation, around 50% strain permitted in both zygapophyses and disks, and a small amount of vertebral intersection permitted. Our approach successfully reconstructs magnitudes and craniocaudal patterns of motion obtained from ex vivo experiments, supporting its potential utility. It also performs better than more typical methods that rely solely on bony intersection, emphasizing the importance of accounting for soft tissues. We estimated the sensitivity of the analyses to vertebral model construction by varying joint spacing, degree of overlap, and the impact of landmark placement. The effect of these factors was small relative to biological variation craniocaudally and between bending directions. We also present a new approach for estimating joint stiffness directly from oROM and morphometric measurements that can successfully reconstruct the craniocaudal patterns, but not magnitudes, derived from experimental data. Together, this work represents a significant step forward for understanding vertebral function in difficult-to-study (e.g., rare or extinct) species, paving the way for a broader understanding of patterns of functional evolution in the axial skeleton.
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Affiliation(s)
- K E Jones
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - R J Brocklehurst
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - S E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
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6
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Three-dimensional topology optimization model to simulate the external shapes of bone. PLoS Comput Biol 2021; 17:e1009043. [PMID: 34133416 PMCID: PMC8208580 DOI: 10.1371/journal.pcbi.1009043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 05/05/2021] [Indexed: 11/19/2022] Open
Abstract
Elucidation of the mechanism by which the shape of bones is formed is essential for understanding vertebrate development. Bones support the body of vertebrates by withstanding external loads, such as those imposed by gravity and muscle tension. Many studies have reported that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that bone shape adapts to external load. In fact, by simulating this relationship through topology optimization, the internal trabecular structure of bones can be successfully reproduced, thereby facilitating the study of bone diseases. In contrast, there have been few attempts to simulate the external structure of bones, which determines vertebrate morphology. However, the external shape of bones may be reproduced through topology optimization because cells of the same type form both the internal and external structures of bones. Here, we constructed a three-dimensional topology optimization model to attempt the reproduction of the external shape of teleost vertebrae. In teleosts, the internal structure of the vertebral bodies is invariable, exhibiting an hourglass shape, whereas the lateral structure supporting the internal structure differs among species. Based on the anatomical observations, we applied different external loads to the hourglass-shaped part. The simulations produced a variety of three-dimensional structures, some of which exhibited several structural features similar to those of actual teleost vertebrae. In addition, by adjusting the geometric parameters, such as the width of the hourglass shape, we reproduced the variation in the teleost vertebrae shapes. These results suggest that a simulation using topology optimization can successfully reproduce the external shapes of teleost vertebrae. By applying our topology optimization model to various bones of vertebrates, we can understand how the external shape of bones adapts to external loads. In this paper, we developed a computational method to investigate the relationship between three-dimensional bone shape and external loads imposed on bones. Many studies report that bone formation varies in response to external loads. An increased external load induces bone synthesis, whereas a decreased external load induces bone resorption. This relationship led to the hypothesis that the shape of bones adapts to external load. However, it remains unclear whether this hypothesis can explain the shape of bones. Here, we constructed a three-dimensional mathematical model that imitates the cellular activities of bone formation to attempt the reproduction of the shape of teleost vertebrae. In teleosts, the shape of the vertebrae differs among the species. We set the multiple types of external load conditions in the simulations and compared the simulation results with different teleost vertebrae. The produced structures that can resist the deformation of the surrounding tissues exhibited multiple structural features similar to the vertebrae of several teleost species. This result shows that the formation of bone shape can be explained by the adaptation to external load.
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Martín-Serra A, Pérez-Ramos A, Pastor FJ, Velasco D, Figueirido B. Phenotypic integration in the carnivoran backbone and the evolution of functional differentiation in metameric structures. Evol Lett 2021; 5:251-264. [PMID: 34136273 DOI: 10.1002/evl3.224] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 02/10/2021] [Accepted: 02/23/2021] [Indexed: 11/06/2022] Open
Abstract
Explaining the origin and evolution of a vertebral column with anatomically distinct regions that characterizes the tetrapod body plan provides understanding of how metameric structures become repeated and how they acquire the ability to perform different functions. However, despite many decades of inquiry, the advantages and costs of vertebral column regionalization in anatomically distinct blocks, their functional specialization, and how they channel new evolutionary outcomes are poorly understood. Here, we investigate morphological integration (and how this integration is structured [modularity]) between all the presacral vertebrae of mammalian carnivorans to provide a better understanding of how regionalization in metameric structures evolves. Our results demonstrate that the subunits of the presacral column are highly integrated. However, underlying to this general pattern, three sets of vertebrae are recognized as presacral modules-the cervical module, the anterodorsal module, and the posterodorsal module-as well as one weakly integrated vertebra (diaphragmatic) that forms a transition between both dorsal modules. We hypothesize that the strength of integration organizing the axial system into modules may be associated with motion capability. The highly integrated anterior dorsal module coincides with a region with motion constraints to avoid compromising ventilation, whereas for the posterior dorsal region motion constraints avoid exceeding extension of the posterior back. On the other hand, the weakly integrated diaphragmatic vertebra belongs to the "Diaphragmatic joint complex"-a key region of the mammalian column of exceedingly permissive motion. Our results also demonstrate that these modules do not match with the traditional morphological regions, and we propose natural selection as the main factor shaping this pattern to stabilize some regions and to allow coordinate movements in others.
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Affiliation(s)
- Alberto Martín-Serra
- Departamento de Ecología y Geología, Facultad de Ciencias Universidad de Málaga Málaga 29071 Spain
| | - Alejandro Pérez-Ramos
- Departamento de Ecología y Geología, Facultad de Ciencias Universidad de Málaga Málaga 29071 Spain
| | - Francisco J Pastor
- Departmento de Anatomía y Radiología, Museo de Anatomía Universidad de Valladolid Valladolid 47002 Spain
| | - David Velasco
- Departamento de Ecología y Geología, Facultad de Ciencias Universidad de Málaga Málaga 29071 Spain
| | - Borja Figueirido
- Departamento de Ecología y Geología, Facultad de Ciencias Universidad de Málaga Málaga 29071 Spain
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Araújo JVS, de Barros GM, Cavalcante MMADS, Silva ABSD, Monção ÉDC, Mendonça TGS, Mendes Júnior AC. Morphological features of lower respiratory tract of nine-banded armadillo (Dasypus novemcinctus, Linnaeus, 1758). Anat Histol Embryol 2020; 50:234-239. [PMID: 32997356 DOI: 10.1111/ahe.12620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 08/06/2020] [Accepted: 08/22/2020] [Indexed: 11/28/2022]
Abstract
The nine-banded armadillo (Dasypus novemcinctus) is a mammal of the Xenarthra Superorder, which inhabits Central, South and North America. Few morphological descriptions are observed in this species, including the respiratory tract; therefore, the objective of this study was to describe morphologically the lower respiratory tract of the nine-banded armadillo. Five animals were dissected, and the macroscopic and microscopic aspects were analysed. In the anatomical analysis, the perfusion technique was performed with vinyl acetate and the fragments of tissue from respiratory organs (trachea, bronchi, bronchioles and pulmonary lobes) were stained with haematoxylin-eosin for visualization under optical microscopy. Containing about 30 cartilage rings, the trachea is lined internally with ciliated pseudostratified epithelial tissue. The lungs are subdivided into lobes by deep interlobar fissures, with two lobes in the right lung and three lobes in the left lung. Microscopically, the primary, secondary and tertiary bronchi have non-ciliated pseudostratified epithelium with goblet cells. It was found that macro- and microscopically the respiratory tract of this species is similar to existing xenarthras and other excavator animals. These data provide subsidies for the clinic and preservation of this species.
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Affiliation(s)
| | | | | | | | - Élida da Costa Monção
- Department of Morphology, Health Sciences Center, Federal University of Piaui, Teresina, Brazil
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9
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Jurestovsky DJ, Jayne BC, Astley HC. Experimental modification of morphology reveals the effects of the zygosphene-zygantrum joint on the range of motion of snake vertebrae. J Exp Biol 2020; 223:jeb216531. [PMID: 32127376 DOI: 10.1242/jeb.216531] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/24/2020] [Indexed: 11/20/2022]
Abstract
Variation in joint shape and soft tissue can alter range of motion (ROM) and create trade-offs between stability and flexibility. The shape of the distinctive zygosphene-zygantrum joint of snake vertebrae has been hypothesized to prevent axial torsion (twisting), but its function has never been tested experimentally. We used experimental manipulation of morphology to determine the role of the zygosphene-zygantrum articulation by micro-computed tomography (μCT) scanning and 3D printing two mid-body vertebrae with unaltered shape and with the zygosphene digitally removed for four species of phylogenetically diverse snakes. We recorded the angular ROM while manipulating the models in yaw (lateral bending), pitch (dorsoventral bending) and roll (axial torsion). Removing the zygosphene typically increased yaw and dorsal pitch ROM. In the normal vertebrae, roll was <2.5 deg for all combinations of pitch and yaw. Roll increased in altered vertebrae but only for combinations of high yaw and ventral pitch that were near or beyond the limits of normal vertebra ROM. In the prairie rattlesnake and brown tree snake, roll in the altered vertebrae was always limited by bony processes other than the zygosphene, whereas in the altered vertebrae of the corn snake and boa constrictor, roll ROM was unconstrained when the pre- and post-zygapophyses no longer overlapped. The zygosphene acts as a bony limit for yaw and dorsal pitch, indirectly preventing roll by precluding most pitch and yaw combinations where roll could occur and potentially allowing greater forces to be applied across the vertebral column than would be possible with only soft-tissue constraints.
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Affiliation(s)
- Derek J Jurestovsky
- Department of Biology, University of Akron, 302 E. Buchtel Avenue, Akron, OH 44325, USA
| | - Bruce C Jayne
- Department of Biological Sciences, University of Cincinnati, PO Box 210006, Cincinnati, OH 45221-0006, USA
| | - Henry C Astley
- Department of Biology, University of Akron, 302 E. Buchtel Avenue, Akron, OH 44325, USA
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10
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Terray L, Plateau O, Abourachid A, Böhmer C, Delapré A, de la Bernardie X, Cornette R. Modularity of the Neck in Birds (Aves). Evol Biol 2020. [DOI: 10.1007/s11692-020-09495-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Jones KE, Gonzalez S, Angielczyk KD, Pierce SE. Regionalization of the axial skeleton predates functional adaptation in the forerunners of mammals. Nat Ecol Evol 2020; 4:470-478. [PMID: 32015524 DOI: 10.1038/s41559-020-1094-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/02/2020] [Indexed: 11/10/2022]
Abstract
The evolution of semi-independent modules is hypothesized to underlie the functional diversification of serially repeating (metameric) structures. The mammal vertebral column is a classic example of a metameric structure that is both modular, with well-defined morphological regions, and functionally differentiated. How the evolution of regions is related to their functional differentiation in the forerunners of mammals remains unclear. Here we gathered morphometric and biomechanical data on the presacral vertebrae of two extant species that bracket the synapsid-mammal transition and use the relationship between form and function to predict functional differentiation in extinct non-mammalian synapsids. The origin of vertebral functional diversity does not correlate with the evolution of new regions but appears late in synapsid evolution. This decoupling of regions from functional diversity implies that an adaptive trigger is needed to exploit existing modularity. We propose that the release of axial respiratory constraints, combined with selection for novel mammalian behaviours in Late Triassic cynodonts, drove the functional divergence of pre-existing morphological regions.
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Affiliation(s)
- Katrina E Jones
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Cambridge, MA, USA.
| | - Sarah Gonzalez
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Cambridge, MA, USA
| | - Kenneth D Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA
| | - Stephanie E Pierce
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Cambridge, MA, USA.
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12
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Jones KE, Angielczyk KD, Pierce SE. Stepwise shifts underlie evolutionary trends in morphological complexity of the mammalian vertebral column. Nat Commun 2019; 10:5071. [PMID: 31699978 PMCID: PMC6838112 DOI: 10.1038/s41467-019-13026-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 10/11/2019] [Indexed: 11/09/2022] Open
Abstract
A fundamental concept in evolutionary biology is that life tends to become more complex through geologic time, but empirical examples of this phenomenon are controversial. One debate is whether increasing complexity is the result of random variations, or if there are evolutionary processes which actively drive its acquisition, and if these processes act uniformly across clades. The mammalian vertebral column provides an opportunity to test these hypotheses because it is composed of serially-repeating vertebrae for which complexity can be readily measured. Here we test seven competing hypotheses for the evolution of vertebral complexity by incorporating fossil data from the mammal stem lineage into evolutionary models. Based on these data, we reject Brownian motion (a random walk) and uniform increasing trends in favor of stepwise shifts for explaining increasing complexity. We hypothesize that increased aerobic capacity in non-mammalian cynodonts may have provided impetus for increasing vertebral complexity in mammals.
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Affiliation(s)
- Katrina E Jones
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
| | - Kenneth D Angielczyk
- Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605-2496, USA
| | - Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
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13
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Williams SA, Spear JK, Petrullo L, Goldstein DM, Lee AB, Peterson AL, Miano DA, Kaczmarek EB, Shattuck MR. Increased variation in numbers of presacral vertebrae in suspensory mammals. Nat Ecol Evol 2019; 3:949-956. [DOI: 10.1038/s41559-019-0894-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 04/08/2019] [Indexed: 11/09/2022]
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14
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Costa FR, Clerici GP, Lobo-Ribeiro L, Rosa PS, Rocha-Barbosa O. Analysis of the spatio-temporal parameters of gaits in Dasypus novemcinctus
(Xenarthra: Dasypodidae). ACTA ZOOL-STOCKHOLM 2017. [DOI: 10.1111/azo.12231] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Hautier L, Oliver JD, Pierce SE. An Overview of Xenarthran Developmental Studies with a Focus on the Development of the Xenarthrous Vertebrae. J MAMM EVOL 2017. [DOI: 10.1007/s10914-017-9412-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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The Postcranial Musculoskeletal System of Xenarthrans: Insights from over Two Centuries of Research and Future Directions. J MAMM EVOL 2017. [DOI: 10.1007/s10914-017-9408-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Kambic RE, Biewener AA, Pierce SE. Experimental determination of three-dimensional cervical joint mobility in the avian neck. Front Zool 2017; 14:37. [PMID: 28747987 PMCID: PMC5525307 DOI: 10.1186/s12983-017-0223-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/11/2017] [Indexed: 11/16/2022] Open
Abstract
Background Birds have highly mobile necks, but neither the details of how they realize complex poses nor the evolution of this complex musculoskeletal system is well-understood. Most previous work on avian neck function has focused on dorsoventral flexion, with few studies quantifying lateroflexion or axial rotation. Such data are critical for understanding joint function, as musculoskeletal movements incorporate motion around multiple degrees of freedom simultaneously. Here we use biplanar X-rays on wild turkeys to quantify three-dimensional cervical joint range of motion in an avian neck to determine patterns of mobility along the cranial-caudal axis. Results Range of motion can be generalized to a three-region model: cranial joints are ventroflexed with high axial and lateral mobility, caudal joints are dorsiflexed with little axial rotation but high lateroflexion, and middle joints show varying amounts axial rotation and a low degree of lateroflexion. Nonetheless, variation within and between regions is high. To attain complex poses, substantial axial rotation can occur at joints caudal to the atlas/axis complex and zygapophyseal joints can reduce their overlap almost to osteological disarticulation. Degrees of freedom interact at cervical joints; maximum lateroflexion occurs at different dorsoventral flexion angles at different joints, and axial rotation and lateroflexion are strongly coupled. Further, patterns of joint mobility are strongly predicted by cervical morphology. Conclusion Birds attain complex neck poses through a combination of mobile intervertebral joints, coupled rotations, and highly flexible zygapophyseal joints. Cranial-caudal patterns of joint mobility are tightly linked to cervical morphology, such that function can be predicted by form. The technique employed here provides a repeatable protocol for studying neck function in a broad array of taxa that will be directly comparable. It also serves as a foundation for future work on the evolution of neck mobility along the line from non-avian theropod dinosaurs to birds. Electronic supplementary material The online version of this article (doi:10.1186/s12983-017-0223-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Robert E Kambic
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138 USA.,Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, Bedford, MA 01730 USA
| | - Andrew A Biewener
- Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, Bedford, MA 01730 USA
| | - Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138 USA
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Gaudin TJ, Nyakatura JA. Epaxial Musculature in Armadillos, Sloths, and Opossums: Functional Significance and Implications for the Evolution of Back Muscles in the Xenarthra. J MAMM EVOL 2017. [DOI: 10.1007/s10914-017-9402-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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