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Bird EE, Kivell TL, Dunmore CJ, Tocheri MW, Skinner MM. Trabecular bone structure of the proximal capitate in extant hominids and fossil hominins with implications for midcarpal joint loading and the dart-thrower's motion. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:e24824. [PMID: 37493308 DOI: 10.1002/ajpa.24824] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 05/05/2023] [Accepted: 07/10/2023] [Indexed: 07/27/2023]
Abstract
OBJECTIVES This research examines whether the distribution of trabecular bone in the proximal capitates of extant hominids, as well as several fossil hominin taxa, is associated with the oblique path of the midcarpal joint known as the dart-thrower's motion (DTM). MATERIALS AND METHODS We analyzed proximal capitates from extant (Pongo n = 12; Gorilla n = 11; Pan n = 10; fossil and recent Homo sapiens n = 29) and extinct (Australopithecus sediba n = 2; Homo naledi n = 1; Homo floresiensis n = 2; Neandertals n = 3) hominids using a new canonical holistic morphometric analysis, which quantifies and visualizes the distribution of trabecular bone using relative bone volume as a fraction of total volume (rBV/TV). RESULTS Homo sapiens and Neandertals had a continuous band of high rBV/TV that extended across the scaphoid, lunate, and hamate subarticular regions, but other fossil hominins and extant great apes did not. A. sediba expressed a distinct combination of human-like and Pan-like rBV/TV distribution. Both H. floresiensis and H. naledi had high rBV/TV on the ulnar-side of the capitate but low rBV/TV on the radial-side. CONCLUSION The proximal capitates of H. sapiens and Neandertals share a distinctive distribution of trabecular bone that suggests that these two species of Homo regularly load(ed) their midcarpal joints along the full extent of the oblique path of the DTM. The observed pattern in A. sediba suggests that human-like stress at the capito-scaphoid articular surface was combined with Pan-like wrist postures, whereas the patterns in H. floresiensis and H. naledi suggest their midcarpal joints were loaded differently from that of H. sapiens and Neandertals.
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Affiliation(s)
- Emma E Bird
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Centre for Human Evolution Research, Natural History Museum, London, UK
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
| | - Christopher J Dunmore
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Matthew W Tocheri
- Department of Anthropology, Lakehead University, Thunder Bay, Ontario, Canada
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
- Australian Research Council, Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, Australia
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
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Cazenave M, Kivell TL. Challenges and perspectives on functional interpretations of australopith postcrania and the reconstruction of hominin locomotion. J Hum Evol 2023; 175:103304. [PMID: 36563461 DOI: 10.1016/j.jhevol.2022.103304] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 12/24/2022]
Abstract
In 1994, Hunt published the 'postural feeding hypothesis'-a seminal paper on the origins of hominin bipedalism-founded on the detailed study of chimpanzee positional behavior and the functional inferences derived from the upper and lower limb morphology of the Australopithecus afarensis A.L. 288-1 partial skeleton. Hunt proposed a model for understanding the potential selective pressures on hominins, made robust, testable predictions based on Au. afarensis functional morphology, and presented a hypothesis that aimed to explain the dual functional signals of the Au. afarensis and, more generally, early hominin postcranium. Here we synthesize what we have learned about Au. afarensis functional morphology and the dual functional signals of two new australopith discoveries with relatively complete skeletons (Australopithecus sediba and StW 573 'Australopithecus prometheus'). We follow this with a discussion of three research approaches that have been developed for the purpose of drawing behavioral inferences in early hominins: (1) developments in the study of extant apes as models for understanding hominin origins; (2) novel and continued developments to quantify bipedal gait and locomotor economy in extant primates to infer the locomotor costs from the anatomy of fossil taxa; and (3) novel developments in the study of internal bone structure to extract functional signals from fossil remains. In conclusion of this review, we discuss some of the inherent challenges of the approaches and methodologies adopted to reconstruct the locomotor modes and behavioral repertoires in extinct primate taxa, and notably the assessment of habitual terrestrial bipedalism in early hominins.
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Affiliation(s)
- Marine Cazenave
- Division of Anthropology, American Museum of Natural History, New York, USA; Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK; Department of Anatomy, Faculty of Health Sciences, University of Pretoria, South Africa.
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
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Figus C, Stephens NB, Sorrentino R, Bortolini E, Arrighi S, Higgins OA, Lugli F, Marciani G, Oxilia G, Romandini M, Silvestrini S, Baruffaldi F, Belcastro MG, Bernardini F, Festa A, Hajdu T, Mateovics‐László O, Pap I, Szeniczey T, Tuniz C, Ryan TM, Benazzi S. Morphologies in-between: The impact of the first steps on the human talus. Anat Rec (Hoboken) 2023; 306:124-142. [PMID: 35656925 PMCID: PMC10083965 DOI: 10.1002/ar.25010] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/15/2022] [Accepted: 05/16/2022] [Indexed: 01/29/2023]
Abstract
OBJECTIVE The development of bipedalism is a very complex activity that contributes to shaping the anatomy of the foot. The talus, which starts ossifying in utero, may account for the developing stages from the late gestational phase onwards. Here, we explore the early development of the talus in both its internal and external morphology to broaden the knowledge of the anatomical changes that occur during early development. MATERIALS AND METHODS The sample consists of high-resolution microCT scans of 28 modern juvenile tali (from 36 prenatal weeks to 2 years), from a broad chronological range from the Late Roman period to the 20th century. We applied geometric morphometric and whole-bone trabecular analysis to investigate the early talar morphological changes. RESULTS In the youngest group (<6 postnatal months), the immature external shell is accompanied by an isotropic internal structure, with thin and densely packed trabeculae. After the initial attempts of locomotion, bone volume fraction decreases, while anisotropy and trabecular thickness increase. These internal changes correspond to the maturation of the external shell, which is now more defined and shows the development of the articular surfaces. DISCUSSION The internal and external morphology of the human talus reflects the diverse load on the foot during the initial phases of the bipedal locomotion, with the youngest group potentially reflecting the lack of readiness of the human talus to bear forces and perform bipedal walking. These results highlight the link between mechanical loading and bone development in the human talus during the acquisition of bipedalism, providing new insight into the early phases of talar development.
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Affiliation(s)
- Carla Figus
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Nicholas B. Stephens
- Department of AnthropologyPennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Rita Sorrentino
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Department of Biological, Geological and Environmental Sciences – BigeaUniversity of BolognaBolognaItaly
| | - Eugenio Bortolini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Human Ecology and Archaeology (HUMANE)IMF, CSI0CBarcelonaSpain
| | - Simona Arrighi
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Owen A. Higgins
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Federico Lugli
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Giulia Marciani
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Research Unit Prehistory and Anthropology, Department of Physical Sciences, Earth and EnvironmentUniversity of SienaSienaItaly
| | - Gregorio Oxilia
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Matteo Romandini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Sara Silvestrini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Fabio Baruffaldi
- Laboratory of Medical TechnologyIRCCS Istituto Ortopedico RizzoliBolognaItaly
| | - Maria Giovanna Belcastro
- Department of Biological, Geological and Environmental Sciences – BigeaUniversity of BolognaBolognaItaly
| | - Federico Bernardini
- Department of Humanistic StudiesUniversità Ca'FoscariVeneziaItaly
- Multidisciplinary LaboratoryAbdus Salam International Centre for Theoretical PhysicsTriesteItaly
| | - Anna Festa
- Laboratory of Medical TechnologyIRCCS Istituto Ortopedico RizzoliBolognaItaly
| | - Tamás Hajdu
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
| | | | - Ildiko Pap
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
- Department of Biological Anthropology, Institute of Biology, Faculty of Science and InformaticsSzeged UniversitySzegedHungary
- Department of AnthropologyHungarian Natural History MuseumBudapestHungary
| | - Tamás Szeniczey
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
| | - Claudio Tuniz
- Multidisciplinary LaboratoryAbdus Salam International Centre for Theoretical PhysicsTriesteItaly
- Centre for Archaeological ScienceUniversity of WollongongWollongongNew South WalesAustralia
| | - Timothy M. Ryan
- Department of AnthropologyPennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Stefano Benazzi
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Department of Human EvolutionMax Planck Institute for Evolutionary AnthropologyLeipzigGermany
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Figus C, Stephens NB, Sorrentino R, Bortolini E, Arrighi S, Lugli F, Marciani G, Oxilia G, Romandini M, Silvestrini S, Baruffaldi F, Belcastro MG, Bernardini F, Erjavec I, Festa A, Hajdu T, Mateovics‐László O, Novak M, Pap I, Szeniczey T, Tuniz C, Ryan TM, Benazzi S. Human talar ontogeny: Insights from morphological and trabecular changes during postnatal growth. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2022; 179:211-228. [PMCID: PMC9804293 DOI: 10.1002/ajpa.24596] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/19/2022] [Accepted: 07/04/2022] [Indexed: 08/11/2023]
Abstract
Objectives The study of the development of human bipedalism can provide a unique perspective on the evolution of morphology and behavior across species. To generate new knowledge of these mechanisms, we analyze changes in both internal and external morphology of the growing human talus in a sample of modern human juveniles using an innovative approach. Materials and Methods The sample consists of high‐resolution microCT scans of 70 modern juvenile tali, aged between 8 postnatal weeks and 10 years old, from a broad chronological range from Middle/Late Neolithic, that is, between 4800 and 4500 BCE, to the 20th century. We applied geometric morphometric and whole‐bone trabecular analysis (bone volume fraction, degree of anisotropy, trabecular number, thickness, and spacing) to all specimens to identify changes in the external and internal morphology during growth. Morphometric maps were also generated. Results During the first year of life, the talus has an immature and globular shape, with a dense, compact, and rather isotropic trabecular architecture, with numerous trabeculae packed closely together. This pattern changes while children acquire a more mature gait, and the talus tends to have a lower bone volume fraction, a higher anisotropy, and a more mature shape. Discussion The changes in talar internal and external morphologies reflect the different loading patterns experienced during growth, gradually shifting from an “unspecialized” morphology to a more complex one, following the development of bipedal gait. Our research shows that talar plasticity, even though genetically driven, may show mechanical influences and contribute to tracking the main locomotor milestones.
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Affiliation(s)
- Carla Figus
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Nicholas B. Stephens
- Department of AnthropologyPennsylvania State UniversityUniversity ParkPennsylvaniaUSA
| | - Rita Sorrentino
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Department of Biological, Geological and Environmental Sciences – BigeaUniversity of BolognaBolognaItaly
| | - Eugenio Bortolini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
- Human Ecology and Archaeology (HUMANE)BarcelonaSpain
| | - Simona Arrighi
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Federico Lugli
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Giulia Marciani
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Gregorio Oxilia
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Matteo Romandini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Sara Silvestrini
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
| | - Fabio Baruffaldi
- Laboratory of Medical TechnologyIRCCS Istituto Ortopedico RizzoliBolognaItaly
| | - Maria Giovanna Belcastro
- Department of Biological, Geological and Environmental Sciences – BigeaUniversity of BolognaBolognaItaly
| | - Federico Bernardini
- Department of Humanistic StudiesUniversità Ca'FoscariVeneziaItaly
- Multidisciplinary LaboratoryAbdus Salam International Centre for Theoretical PhysicsTriesteItaly
| | - Igor Erjavec
- Laboratory for Mineralized TissueCentre for Translational and Clinical ResearchZagrebCroatia
| | - Anna Festa
- Laboratory of Medical TechnologyIRCCS Istituto Ortopedico RizzoliBolognaItaly
| | - Tamás Hajdu
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
| | | | - Mario Novak
- Centre for Applied BioanthropologyInstitute for Anthropological ResearchZagrebCroatia
| | - Ildikó Pap
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
- Department of AnthropologyHungarian Natural History MuseumBudapestHungary
- Department of Biological Anthropology, Institute of Biology, Faculty of Science and InformaticsSzeged UniversitySzegedHungary
| | - Tamás Szeniczey
- Department of Biological Anthropology, Institute of Biology, Faculty of ScienceEötvös Loránd UniversityBudapestHungary
| | - Claudio Tuniz
- Multidisciplinary LaboratoryAbdus Salam International Centre for Theoretical PhysicsTriesteItaly
- Centre for Archaeological ScienceUniversity of WollongongWollongongAustralia
| | - Timothy M. Ryan
- Department of AnthropologyPennsylvania State UniversityUniversity ParkPennsylvaniaUSA
| | - Stefano Benazzi
- Department of Cultural HeritageUniversity of BolognaRavennaItaly
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Bachmann S, Dunmore CJ, Skinner MM, Pahr DH, Synek A. A computational framework for canonical holistic morphometric analysis of trabecular bone. Sci Rep 2022; 12:5187. [PMID: 35338187 PMCID: PMC8956643 DOI: 10.1038/s41598-022-09063-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 03/14/2022] [Indexed: 11/22/2022] Open
Abstract
Bone is a remarkable, living tissue that functionally adapts to external loading. Therefore, bone shape and internal structure carry information relevant to many disciplines, including medicine, forensic science, and anthropology. However, morphometric comparisons of homologous regions across different individuals or groups are still challenging. In this study, two methods were combined to quantify such differences: (1) Holistic morphometric analysis (HMA) was used to quantify morphometric values in each bone, (2) which could then be mapped to a volumetric mesh of a canonical bone created by a statistical free-form deformation model (SDM). Required parameters for this canonical holistic morphometric analysis (cHMA) method were identified and the robustness of the method was evaluated. The robustness studies showed that the SDM converged after one to two iterations, had only a marginal bias towards the chosen starting image, and could handle large shape differences seen in bones of different species. Case studies were performed on metacarpal bones and proximal femora of different primate species to confirm prior study results. The differences between species could be visualised and statistically analysed in both case studies. cHMA provides a framework for performing quantitative comparisons of different morphometric quantities across individuals or groups. These comparisons facilitate investigation of the relationship between spatial morphometric variations and function or pathology, or both.
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Affiliation(s)
- Sebastian Bachmann
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria.
| | - Christopher J Dunmore
- School of Anthropology and Conservation, Skeletal Biology Research Centre, University of Kent, Canterbury, UK
| | - Matthew M Skinner
- School of Anthropology and Conservation, Skeletal Biology Research Centre, University of Kent, Canterbury, UK
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Dieter H Pahr
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Alexander Synek
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
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Bird EE, Kivell TL, Skinner MM. Patterns of internal bone structure and functional adaptation in the hominoid scaphoid, lunate, and triquetrum. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2021. [DOI: 10.1002/ajpa.24449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Emma E. Bird
- Skeletal Biology Research Centre, School of Anthropology and Conservation University of Kent Canterbury UK
| | - Tracy L. Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation University of Kent Canterbury UK
- Department of Human Evolution Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Matthew M. Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation University of Kent Canterbury UK
- Department of Human Evolution Max Planck Institute for Evolutionary Anthropology Leipzig Germany
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Bird EE, Kivell TL, Skinner MM. Cortical and trabecular bone structure of the hominoid capitate. J Anat 2021; 239:351-373. [PMID: 33942895 PMCID: PMC8273598 DOI: 10.1111/joa.13437] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 01/02/2023] Open
Abstract
Morphological variation in the hominoid capitate has been linked to differences in habitual locomotor activity due to its importance in movement and load transfer at the midcarpal joint proximally and carpometacarpal joints distally. Although the shape of bones and their articulations are linked to joint mobility, the internal structure of bones has been shown experimentally to reflect, at least in part, the loading direction and magnitude experienced by the bone. To date, it is uncertain whether locomotor differences among hominoids are reflected in the bone microarchitecture of the capitate. Here, we apply a whole‐bone methodology to quantify the cortical and trabecular architecture (separately and combined) of the capitate across bipedal (modern Homo sapiens), knuckle‐walking (Pan paniscus, Pan troglodytes, Gorilla sp.), and suspensory (Pongo sp.) hominoids (n = 69). It is hypothesized that variation in bone microarchitecture will differentiate these locomotor groups, reflecting differences in habitual postures and presumed loading force and direction. Additionally, it is hypothesized that trabecular and cortical architecture in the proximal and distal regions, as a result of being part of mechanically divergent joints proximally and distally, will differ across these portions of the capitate. Results indicate that the capitate of knuckle‐walking and suspensory hominoids is differentiated from bipedal Homo primarily by significantly thicker distal cortical bone. Knuckle‐walking taxa are further differentiated from suspensory and bipedal taxa by more isotropic trabeculae in the proximal capitate. An allometric analysis indicates that size is not a significant determinate of bone variation across hominoids, although sexual dimorphism may influence some parameters within Gorilla. Results suggest that internal trabecular and cortical bone is subjected to different forces and functional adaptation responses across the capitate (and possibly other short bones). Additionally, while separating trabecular and cortical bone is normal protocol of current whole‐bone methodologies, this study shows that when applied to carpals, removing or studying the cortical bone separately potentially obfuscates functionally relevant signals in bone structure.
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Affiliation(s)
- Emma E Bird
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Tracy L Kivell
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Harper CM, Ruff CB, Sylvester AD. Gorilla calcaneal morphological variation and ecological divergence. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 174:49-65. [PMID: 32871028 DOI: 10.1002/ajpa.24135] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/11/2020] [Accepted: 08/02/2020] [Indexed: 01/19/2023]
Abstract
OBJECTIVES The primate foot has been extensively investigated because of its role in weight-bearing; however, the calcaneus has been relatively understudied. Here we examine entire gorilla calcaneal external shape to understand its relationship with locomotor behavior. MATERIALS AND METHODS Calcanei of Gorilla gorilla gorilla (n = 43), Gorilla beringei graueri (n = 20), and Gorilla beringei beringei (n = 15) were surface or micro-CT scanned. External shape was analyzed through a three-dimensional geometric morphometric sliding semilandmark analysis. Semilandmarks were slid relative to an updated Procrustes average in order to minimize the bending energy of the thin plate spline interpolation function. Shape variation was summarized using principal components analysis of shape coordinates. Procrustes distances between taxa averages were calculated and resampling statistics run to test pairwise differences. Linear measures were collected and regressed against estimated body mass. RESULTS All three taxa exhibit statistically different morphologies (p < .001 for pairwise comparisons). G. g. gorilla demonstrates an anteroposteriorly elongated calcaneus with a deeper cuboid pivot region and mediolaterally flatter posterior talar facet. G. b. beringei possesses the flattest cuboid and most medially-angled posterior talar facets. G. b. graueri demonstrates intermediate articular facet morphology, a medially-angled tuberosity, and an elongated peroneal trochlea. DISCUSSION Articular facet differences separate gorillas along a locomotor gradient. G. g. gorilla is adapted for arboreality with greater joint mobility, while G. b. beringei is adapted for more stereotypical loads associated with terrestriality. G. b. graueri's unique posterolateral morphology may be due to a secondary transition to greater arboreality from a more terrestrial ancestor.
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Affiliation(s)
- Christine M Harper
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher B Ruff
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Adam D Sylvester
- Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Cortical bone distribution in the femoral neck of Paranthropus robustus. J Hum Evol 2019; 135:102666. [DOI: 10.1016/j.jhevol.2019.102666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 08/20/2019] [Accepted: 08/20/2019] [Indexed: 02/07/2023]
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