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Ravazzano L, Colaianni G, Tarakanova A, Xiao YB, Grano M, Libonati F. Multiscale and multidisciplinary analysis of aging processes in bone. NPJ AGING 2024; 10:28. [PMID: 38879533 PMCID: PMC11180112 DOI: 10.1038/s41514-024-00156-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 05/07/2024] [Indexed: 06/19/2024]
Abstract
The world population is increasingly aging, deeply affecting our society by challenging our healthcare systems and presenting an economic burden, thus turning the spotlight on aging-related diseases: exempli gratia, osteoporosis, a silent disease until you suddenly break a bone. The increase in bone fracture risk with age is generally associated with a loss of bone mass and an alteration in the skeletal architecture. However, such changes cannot fully explain increased fragility with age. To successfully tackle age-related bone diseases, it is paramount to comprehensively understand the fundamental mechanisms responsible for tissue degeneration. Aging mechanisms persist at multiple length scales within the complex hierarchical bone structure, raising the need for a multiscale and multidisciplinary approach to resolve them. This paper aims to provide an overarching analysis of aging processes in bone and to review the most prominent outcomes of bone aging. A systematic description of different length scales, highlighting the corresponding techniques adopted at each scale and motivating the need for combining diverse techniques, is provided to get a comprehensive description of the multi-physics phenomena involved.
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Affiliation(s)
- Linda Ravazzano
- Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Rubattino 81, Milano, 20134, Italy
| | - Graziana Colaianni
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University of Bari Aldo Moro, Piazza Giulio Cesare 11, Bari, 70124, Italy
| | - Anna Tarakanova
- School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, 06269, CT, USA
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, CT, 06269, Storrs, USA
| | - Yu-Bai Xiao
- School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, 06269, CT, USA
| | - Maria Grano
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University of Bari Aldo Moro, Piazza Giulio Cesare 11, Bari, 70124, Italy
| | - Flavia Libonati
- Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Rubattino 81, Milano, 20134, Italy.
- Department of Mechanical, Energy, Management and Transport Engineering - DIME, University of Genova, Via all'Opera Pia 15, Genova, 16145, Italy.
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2
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Smith SM, Heaney LR, Angielczyk KD. Small skeletons show size-specific scaling: an exploration of allometry in the mammalian lumbar spine. Proc Biol Sci 2024; 291:20232868. [PMID: 38628132 PMCID: PMC11021941 DOI: 10.1098/rspb.2023.2868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 03/14/2024] [Indexed: 04/19/2024] Open
Abstract
Studies of vertebrate bone biomechanics often focus on skeletal adaptations at upper extremes of body mass, disregarding the importance of skeletal adaptations at lower extremes. Yet mammals are ancestrally small and most modern species have masses under 5 kg, so the evolution of morphology and function at small size should be prioritized for understanding how mammals subsist. We examined allometric scaling of lumbar vertebrae in the small-bodied Philippine endemic rodents known as cloud rats, which vary in mass across two orders of magnitude (15.5 g-2700 g). External vertebral dimensions scale with isometry or positive allometry, likely relating to body size and nuances in quadrupedal posture. In contrast to most mammalian trabecular bone studies, bone volume fraction and trabecular thickness scale with positive allometry and isometry, respectively. It is physiologically impossible for these trends to continue to the upper extremes of mammalian body size, and we demonstrate a fundamental difference in trabecular bone allometry between large- and small-bodied mammals. These findings have important implications for the biomechanical capabilities of mammalian bone at small body size; for the selective pressures that govern skeletal evolution in small mammals; and for the way we define 'small' and 'large' in the context of vertebrate skeletons.
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Affiliation(s)
- S. M. Smith
- Field Museum of Natural History, 1400 S DuSable Lake Shore Drive, Chicago, IL 60605, USA
| | - L. R. Heaney
- Field Museum of Natural History, 1400 S DuSable Lake Shore Drive, Chicago, IL 60605, USA
| | - K. D. Angielczyk
- Field Museum of Natural History, 1400 S DuSable Lake Shore Drive, Chicago, IL 60605, USA
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3
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Alfieri F, Botton-Divet L, Wölfer J, Nyakatura JA, Amson E. A macroevolutionary common-garden experiment reveals differentially evolvable bone organization levels in slow arboreal mammals. Commun Biol 2023; 6:995. [PMID: 37770611 PMCID: PMC10539518 DOI: 10.1038/s42003-023-05371-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 09/18/2023] [Indexed: 09/30/2023] Open
Abstract
Eco-morphological convergence, i.e., similar phenotypes evolved in ecologically convergent taxa, naturally reproduces a common-garden experiment since it allows researchers to keep ecological factors constant, studying intrinsic evolutionary drivers. The latter may result in differential evolvability that, among individual anatomical parts, causes mosaic evolution. Reconstructing the evolutionary morphology of the humerus and femur of slow arboreal mammals, we addressed mosaicism at different bone anatomical spatial scales. We compared convergence strength, using it as indicator of evolvability, between bone external shape and inner structure, with the former expected to be less evolvable and less involved in convergent evolution, due to anatomical constraints. We identify several convergent inner structural traits, while external shape only loosely follows this trend, and we find confirmation for our assumption in measures of convergence magnitude. We suggest that future macroevolutionary reconstructions based on bone morphology should include structural traits to better detect ecological effects on vertebrate diversification.
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Affiliation(s)
- Fabio Alfieri
- Comparative Zoology, Institute for Biology, Humboldt-Universität zu Berlin, Unter den Linden 6, 10117, Berlin, Germany.
- Museum Für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115, Berlin, Germany.
| | - Léo Botton-Divet
- Comparative Zoology, Institute for Biology, Humboldt-Universität zu Berlin, Unter den Linden 6, 10117, Berlin, Germany
| | - Jan Wölfer
- Comparative Zoology, Institute for Biology, Humboldt-Universität zu Berlin, Unter den Linden 6, 10117, Berlin, Germany
| | - John A Nyakatura
- Comparative Zoology, Institute for Biology, Humboldt-Universität zu Berlin, Unter den Linden 6, 10117, Berlin, Germany
| | - Eli Amson
- Paleontology Department, Staatliches Museum für Naturkunde, Rosenstein 1-3, 70191, Stuttgart, Germany
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4
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Bianucci G, Lambert O, Urbina M, Merella M, Collareta A, Bennion R, Salas-Gismondi R, Benites-Palomino A, Post K, de Muizon C, Bosio G, Di Celma C, Malinverno E, Pierantoni PP, Villa IM, Amson E. A heavyweight early whale pushes the boundaries of vertebrate morphology. Nature 2023; 620:824-829. [PMID: 37532931 DOI: 10.1038/s41586-023-06381-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/28/2023] [Indexed: 08/04/2023]
Abstract
The fossil record of cetaceans documents how terrestrial animals acquired extreme adaptations and transitioned to a fully aquatic lifestyle1,2. In whales, this is associated with a substantial increase in maximum body size. Although an elongate body was acquired early in cetacean evolution3, the maximum body mass of baleen whales reflects a recent diversification that culminated in the blue whale4. More generally, hitherto known gigantism among aquatic tetrapods evolved within pelagic, active swimmers. Here we describe Perucetus colossus-a basilosaurid whale from the middle Eocene epoch of Peru. It displays, to our knowledge, the highest degree of bone mass increase known to date, an adaptation associated with shallow diving5. The estimated skeletal mass of P. colossus exceeds that of any known mammal or aquatic vertebrate. We show that the bone structure specializations of aquatic mammals are reflected in the scaling of skeletal fraction (skeletal mass versus whole-body mass) across the entire disparity of amniotes. We use the skeletal fraction to estimate the body mass of P. colossus, which proves to be a contender for the title of heaviest animal on record. Cetacean peak body mass had already been reached around 30 million years before previously assumed, in a coastal context in which primary productivity was particularly high.
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Affiliation(s)
- Giovanni Bianucci
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
| | - Mario Urbina
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural-Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - Marco Merella
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Alberto Collareta
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Rebecca Bennion
- D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
- Evolution & Diversity Dynamics Lab, UR Geology, Université de Liège, Liège, Belgium
| | - Rodolfo Salas-Gismondi
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural-Universidad Nacional Mayor de San Marcos, Lima, Perú
- Facultad de Ciencias y Filosofía/Centro de Investigación para el Desarrollo Integral y Sostenible, Laboratorios de Investigación y Desarrollo, Universitad Peruana Cayetano Heredia Lima, Lima, Perú
| | - Aldo Benites-Palomino
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural-Universidad Nacional Mayor de San Marcos, Lima, Perú
- Department of Paleontology, University of Zurich, Zurich, Switzerland
| | - Klaas Post
- Natuurhistorisch Museum Rotterdam, Rotterdam, The Netherlands
| | - Christian de Muizon
- Département Origines et Évolution, CR2P (CNRS, MNHN, Sorbonne Université), Muséum National d'Histoire Naturelle, Paris, France
| | - Giulia Bosio
- Dipartimento di Scienze dell'Ambiente e della Terra, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Claudio Di Celma
- School of Science and Technology, University of Camerino, Camerino, Italy
| | - Elisa Malinverno
- Dipartimento di Scienze dell'Ambiente e della Terra, Università degli Studi di Milano-Bicocca, Milano, Italy
| | | | | | - Eli Amson
- Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany.
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5
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Rickman J, Burtner AE, Linden TJ, Santana SE, Law CJ. Size And Locomotor Ecology Have Differing Effects on the External and Internal Morphologies of Squirrel (Rodentia: Sciuridae) Limb Bones. Integr Org Biol 2023; 5:obad017. [PMID: 37361915 PMCID: PMC10286724 DOI: 10.1093/iob/obad017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 04/19/2023] [Accepted: 05/10/2023] [Indexed: 06/28/2023] Open
Abstract
Mammals exhibit a diverse range of limb morphologies that are associated with different locomotor ecologies and structural mechanics. Much remains to be investigated, however, about the combined effects of locomotor modes and scaling on the external shape and structural properties of limb bones. Here, we used squirrels (Sciuridae) as a model clade to examine the effects of locomotor mode and scaling on the external shape and structure of the two major limb bones, the humerus and femur. We quantified humeral and femoral morphologies using 3D geometric morphometrics and bone structure analyses on a sample of 76 squirrel species across their four major ecotypes. We then used phylogenetic generalized linear models to test how locomotor ecology, size, and their interaction influenced morphological traits. We found that size and locomotor mode exhibit different relationships with the external shape and structure of the limb bones, and that these relationships differ between the humerus and femur. External shapes of the humerus and, to a lesser extent, the femur are best explained by locomotor ecology rather than by size, whereas structures of both bones are best explained by interactions between locomotor ecology and scaling. Interestingly, the statistical relationships between limb morphologies and ecotype were lost when accounting for phylogenetic relationships among species under Brownian motion. That assuming Brownian motion confounded these relationships is not surprising considering squirrel ecotypes are phylogenetically clustered; our results suggest that humeral and femoral variation partitioned early between clades and their ecomorphologies were maintained to the present. Overall, our results show how mechanical constraints, locomotor ecology, and evolutionary history may enact different pressures on the shape and structure of limb bones in mammals.
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Affiliation(s)
| | | | - T J Linden
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98105, USA
| | - S E Santana
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98105, USA
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6
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Amson E, Scheyer TM, Martinez Q, Schwermann AH, Koyabu D, He K, Ziegler R. Unique bone microanatomy reveals ancestry of subterranean specializations in mammals. Evol Lett 2022; 6:552-561. [PMID: 36579164 PMCID: PMC9783445 DOI: 10.1002/evl3.303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/06/2022] [Accepted: 09/30/2022] [Indexed: 11/13/2022] Open
Abstract
Acquiring a subterranean lifestyle entails a substantial shift for many aspects of terrestrial vertebrates' biology. Although this lifestyle is associated with multiple instances of convergent evolution, the relative success of some subterranean lineages largely remains unexplained. Here, we focus on the mammalian transitions to life underground, quantifying bone microanatomy through high-resolution X-ray tomography. The true moles stand out in this dataset. Examination of this family's bone histology reveals that the highly fossorial moles acquired a unique phenotype involving large amounts of compacted coarse cancellous bone. This phenotype exceeds the adaptive optimum seemingly shared by several other subterranean mammals and can be traced back to some of the first known members of the family. This remarkable microanatomy was acquired early in the history of the group and evolved faster than the gross morphology innovations of true moles' forelimb. This echoes the pattern described for other lifestyle transitions, such as the acquisition of bone mass specializations in secondarily aquatic tetrapods. Highly plastic traits-such as those pertaining to bone structure-are hence involved in the early stages of different types of lifestyle transitions.
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Affiliation(s)
- Eli Amson
- Staatliches Museum für Naturkunde StuttgartDE‐70191StuttgartGermany
| | - Torsten M. Scheyer
- Palaeontological Institute and MuseumUniversity of ZurichZurichCH‐8006Switzerland
| | - Quentin Martinez
- Staatliches Museum für Naturkunde StuttgartDE‐70191StuttgartGermany
| | - Achim H. Schwermann
- LWL‐Museum für NaturkundeWestfälisches Landesmuseum mit PlanetariumDE‐48161MünsterGermany
| | - Daisuke Koyabu
- Research and Development Center for Precision MedicineUniversity of TsukubaTsukuba305‐8550Japan
| | - Kai He
- Key Laboratory of Conservation and Application in Biodiversity of South China, School of Life SciencesGuangzhou UniversityGuangzhou510006China
| | - Reinhard Ziegler
- Staatliches Museum für Naturkunde StuttgartDE‐70191StuttgartGermany
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7
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Phylogenetic, Allometric, and Ecological Factors Affecting Morphological Variation in the Scapula and Humerus of Spiny Rats (Rodentia: Echimyidae). J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09617-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
AbstractLocomotion, as a fundamental function in mammals directly associated with the use of ecological resources, is expected to have anatomical structures functionally committed that evolved under intense selective pressure, possibly carrying specializations for different locomotor habits. Among caviomorph rodents, the family Echimyidae stands out for having the greatest species richness, with relatively well-resolved phylogenetic relationships, wide variation in body mass, and remarkable diversity of locomotor habits, including arboreal, scansorial, semi-aquatic, semifossorial, and terrestrial forms. Thus, Echimyidae constitutes a promising model for understanding how phylogenetic, allometric, and ecological factors affect the evolution of postcranial structures directly linked to locomotor function. We investigated the influence of these three factors on scapular and humeral morphological variation in 38 echimyid species using two-dimensional geometric morphometry and phylogenetically informed comparative methods. Scapular and humeral shape variation had a low correlation with body mass and structure size, conveying a small or negligible allometric effect. Conversely, a significant moderate to strong phylogenetic signal was detected in both structures, suggesting that an important part of their morphometric variation results from shared evolutionary history. Notably, morphological variation of the scapula was extensively structured by phylogeny, without the marked influence of locomotor habits, suggesting that its shape may be a suitable taxonomic marker. Finally, locomotor habits were important in structuring the morphological variation of the humerus. Our results suggest that the morphologies of the scapula and humerus, despite being anatomically and functionally interconnected, were differentially shaped by ecological factors associated with locomotor habits.
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8
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Löffler L, Wölfer J, Gavrilei F, Nyakatura JA. Computational Modeling of Gluteus Medius Muscle Moment Arm in Caviomorph Rodents Reveals Ecomorphological Specializations. Front Bioeng Biotechnol 2022; 10:806314. [PMID: 35694234 PMCID: PMC9174681 DOI: 10.3389/fbioe.2022.806314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 03/29/2022] [Indexed: 11/13/2022] Open
Abstract
Vertebrate musculoskeletal locomotion is realized through lever-arm systems. The instantaneous muscle moment arm (IMMA), which is expected to be under selective pressure and thus of interest for ecomorphological studies, is a key aspect of these systems. The IMMA changes with joint motion. It’s length change is technically difficult to acquire and has not been compared in a larger phylogenetic ecomorphological framework, yet. Usually, proxies such as osteological in-levers are used instead. We used 18 species of the ecologically diverse clade of caviomorph rodents to test whether its diversity is reflected in the IMMA of the hip extensor M. gluteus medius. A large IMMA is beneficial for torque generation; a small IMMA facilitates fast joint excursion. We expected large IMMAs in scansorial species, small IMMAs in fossorial species, and somewhat intermediate IMMAs in cursorial species, depending on the relative importance of acceleration and joint angular velocity. We modeled the IMMA over the entire range of possible hip extensions and applied macroevolutionary model comparison to selected joint poses. We also obtained the osteological in-lever of the M. gluteus medius to compare it to the IMMA. At little hip extension, the IMMA was largest on average in scansorial species, while the other two lifestyles were similar. We interpret this as an emphasized need for increased hip joint torque when climbing on inclines, especially in a crouched posture. Cursorial species might benefit from fast joint excursion, but their similarity with the fossorial species is difficult to interpret and could hint at ecological similarities. At larger extension angles, cursorial species displayed the second-largest IMMAs after scansorial species. The larger IMMA optimum results in powerful hip extension which coincides with forward acceleration at late stance beneficial for climbing, jumping, and escaping predators. This might be less relevant for a fossorial lifestyle. The results of the in-lever only matched the IMMA results of larger hip extension angles, suggesting that the modeling of the IMMA provides more nuanced insights into adaptations of musculoskeletal lever-arm systems than this osteological proxy.
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Lang MM, Bertrand OC, San Martin Flores G, Law CJ, Abdul‐Sater J, Spakowski S, Silcox MT. Scaling Patterns of Cerebellar Petrosal Lobules in Euarchontoglires: Impacts of Ecology and Phylogeny. Anat Rec (Hoboken) 2022; 305:3472-3503. [DOI: 10.1002/ar.24929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 02/02/2022] [Accepted: 02/21/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Madlen M. Lang
- Department of Anthropology University of Toronto Scarborough Toronto ON Canada
| | - Ornella C. Bertrand
- School of GeoSciences University of Edinburgh, Grant Institute Edinburgh Scotland UK
| | | | - Chris J. Law
- Richard Gilder Graduate School, Department of Mammalogy, and Division of Paleontology American Museum of Natural History, 200 Central Park West New York NY
- Department of Biology University of Washington Seattle WA
- The University of Texas at Austin Austin TX
| | - Jade Abdul‐Sater
- Department of Anthropology University of Toronto Scarborough Toronto ON Canada
| | - Shayda Spakowski
- Department of Anthropology University of Toronto Scarborough Toronto ON Canada
| | - Mary T. Silcox
- Department of Anthropology University of Toronto Scarborough Toronto ON Canada
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10
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Subaqueous foraging among carnivorous dinosaurs. Nature 2022; 603:852-857. [PMID: 35322229 DOI: 10.1038/s41586-022-04528-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 02/07/2022] [Indexed: 01/16/2023]
Abstract
Secondary aquatic adaptations evolved independently more than 30 times from terrestrial vertebrate ancestors1,2. For decades, non-avian dinosaurs were believed to be an exception to this pattern. Only a few species have been hypothesized to be partly or predominantly aquatic3-11. However, these hypotheses remain controversial12,13, largely owing to the difficulty of identifying unambiguous anatomical adaptations for aquatic habits in extinct animals. Here we demonstrate that the relationship between bone density and aquatic ecologies across extant amniotes provides a reliable inference of aquatic habits in extinct species. We use this approach to evaluate the distribution of aquatic adaptations among non-avian dinosaurs. We find strong support for aquatic habits in spinosaurids, associated with a marked increase in bone density, which precedes the evolution of more conspicuous anatomical modifications, a pattern also observed in other aquatic reptiles and mammals14-16. Spinosaurids are revealed to be aquatic specialists with surprising ecological disparity, including subaqueous foraging behaviour in Spinosaurus and Baryonyx, and non-diving habits in Suchomimus. Adaptation to aquatic environments appeared in spinosaurids during the Early Cretaceous, following their divergence from other tetanuran theropods during the Early Jurassic17.
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11
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Smith SM, Angielczyk KD. A shrewd inspection of vertebral regionalization in large shrews (Soricidae: Crocidurinae). Integr Org Biol 2022; 4:obac006. [PMID: 35291671 PMCID: PMC8915212 DOI: 10.1093/iob/obac006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
The regionalization of the mammalian spinal column is an important evolutionary, developmental, and functional hallmark of the clade. Vertebral column regions are usually defined using transitions in external bone morphology, such as the presence of transverse foraminae or rib facets, or measurements of vertebral shape. Yet the internal structure of vertebrae, specifically the trabecular (spongy) bone, plays an important role in vertebral function, and is subject to the same variety of selective, functional, and developmental influences as external bone morphology. Here we investigated regionalization of external and trabecular bone morphology in the vertebral column of a group of shrews (family Soricidae). The primary goals of this study were to: 1) determine if vertebral trabecular bone morphology is regionalized in large shrews, and if so, in what configuration relative to external morphology; 2) assess correlations between trabecular bone regionalization and functional or developmental influences; and 3) determine if external and trabecular bone regionalization patterns provide clues about the function of the highly modified spinal column of the hero shrew Scutisorex.
Trabecular bone is regionalized along the soricid vertebral column, but the configuration of trabecular bone regions does not match that of the external vertebral morphology, and is less consistent across individuals and species. The cervical region has the most distinct and consistent trabecular bone morphology, with dense trabeculae indicative of the ability to withstand forces in a variety of directions. Scutisorex exhibits an additional external morphology region compared to unmodified shrews, but this region does not correspond to a change in trabecular architecture.
Although trabecular bone architecture is regionalized along the soricid vertebral column, and this regionalization is potentially related to bone functional adaptation, there are likely aspects of vertebral functional regionalization that are not detectable using trabecular bone morphology. For example, the external morphology of the Scutisorex lumbar spine shows signs of an extra functional region that is not apparent in trabecular bone analyses. It is possible that body size and locomotor mode affect the degree to which function is manifest in trabecular bone, and broader study across mammalian size and ecology is warranted to understand the relationship between trabecular bone morphology and other measures of vertebral function such as intervertebral range of motion.
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Affiliation(s)
- Stephanie M Smith
- Field Museum of Natural History, Negaunee Integrative Research Center, 1400 S DuSable Lake Shore Drive, Chicago, IL 60605
| | - Kenneth D Angielczyk
- Field Museum of Natural History, Negaunee Integrative Research Center, 1400 S DuSable Lake Shore Drive, Chicago, IL 60605
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12
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Law CJ. Different evolutionary pathways lead to incomplete convergence of elongate body shapes in carnivoran mammals. Syst Biol 2021; 71:788-796. [PMID: 34791502 DOI: 10.1093/sysbio/syab091] [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: 05/26/2021] [Revised: 11/01/2021] [Accepted: 11/09/2021] [Indexed: 11/13/2022] Open
Abstract
Although convergence is often recognized as a ubiquitous feature across the Tree of Life, whether the underlying traits also exhibit similar evolutionary pathways towards convergent forms puzzles biologists. In carnivoran mammals, "elongate," "slender," and "long" are often used to describe and even to categorize mustelids (martens, polecats, and weasels), herpestids (mongooses), viverrids (civets and genets), and other carnivorans together. But just how similar these carnivorans are and whether there is convergence in the morphological component that contribute to elongation has never been assessed. Here, I found that these qualitatively-described elongate carnivorans exhibited incomplete convergence towards elongate bodies compared to other terrestrial carnivorans. In contrast, the morphological components underlying body shape variation do not exhibit convergence despite evidence that these components are more elongate in elongate carnivorans compared to non-elongate carnivorans. Furthermore, these components also exhibited shorter but different phylogenetic half-lives towards more elongate adaptive peaks, indicating that different selective pressures can create multiple pathways to elongation. Incorporating the fossil record will facilitate further investigation of whether body elongation evolved adaptively or if it is simply a retained ancestral trait.
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Affiliation(s)
- Chris J Law
- Department of Biology, University of Washington, Seattle, WA, 98105; Richard Gilder Graduate School, Department of Mammalogy, and Division of Paleontology, American Museum of Natural History, New York, NY, USA 10024
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13
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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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