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Shirley B, Leonhard I, Murdock DJE, Repetski J, Świś P, Bestmann M, Trimby P, Ohl M, Plümper O, King HE, Jarochowska E. Increasing control over biomineralization in conodont evolution. Nat Commun 2024; 15:5273. [PMID: 38902270 DOI: 10.1038/s41467-024-49526-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 06/07/2024] [Indexed: 06/22/2024] Open
Abstract
Vertebrates use the phosphate mineral apatite in their skeletons, which allowed them to develop tissues such as enamel, characterized by an outstanding combination of hardness and elasticity. It has been hypothesized that the evolution of the earliest vertebrate skeletal tissues, found in the teeth of the extinct group of conodonts, was driven by adaptation to dental function. We test this hypothesis quantitatively and demonstrate that the crystallographic order increased throughout the early evolution of conodont teeth in parallel with morphological adaptation to food processing. With the c-axes of apatite crystals oriented perpendicular to the functional feeding surfaces, the strongest resistance to uniaxial compressional stress is conferred along the long axes of denticles. Our results support increasing control over biomineralization in the first skeletonized vertebrates and allow us to test models of functional morphology and material properties across conodont dental diversity.
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Affiliation(s)
- Bryan Shirley
- Fachgruppe Paläoumwelt, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Isabella Leonhard
- Department of Palaeontology, University of Vienna, Vienna, Austria
- Institute of Evolutionary Biology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | | | - John Repetski
- US Geological Survey-Emeritus, MS 926 A National Center, Reston, USA
| | - Przemysław Świś
- Institute of Evolutionary Biology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, Warsaw, Poland
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Michel Bestmann
- Department of Geology, University of Vienna, Vienna, Austria
| | - Pat Trimby
- Oxford Instruments, High Wycombe, UK
- Carl Zeiss Ltd., Cambridge, UK
| | - Markus Ohl
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Oliver Plümper
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Helen E King
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
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Trimby P, Al-Mosawi M, Al-Jawad M, Micklethwaite S, Aslam Z, Winkelmann A, Piazolo S. The characterisation of dental enamel using transmission Kikuchi diffraction in the scanning electron microscope combined with dynamic template matching. Ultramicroscopy 2024; 260:113940. [PMID: 38422822 DOI: 10.1016/j.ultramic.2024.113940] [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: 06/03/2023] [Revised: 02/11/2024] [Accepted: 02/18/2024] [Indexed: 03/02/2024]
Abstract
The remarkable physical properties of dental enamel can be largely attributed to the structure of the hydroxyapatite (HAp) crystallites on the sub-micrometre scale. Characterising the HAp microstructure is challenging, due to the nanoscale of individual crystallites and practical challenges associated with HAp examination using electron microscopy techniques. Conventional methods for enamel characterisation include imaging using transmission electron microscopy (TEM) or specialised beamline techniques, such as polarisation-dependent imaging contrast (PIC). These provide useful information at the necessary spatial resolution but are not able to measure the full crystallographic orientation of the HAp crystallites. Here we demonstrate the effectiveness of enamel analyses using transmission Kikuchi diffraction (TKD) in the scanning electron microscope, coupled with newly-developed pattern matching methods. The pattern matching approach, using dynamic template matching coupled with subsequent orientation refinement, enables robust indexing of even poor-quality TKD patterns, resulting in significantly improved data quality compared to conventional diffraction pattern indexing methods. The potential of this method for the analysis of nanocrystalline enamel structures is demonstrated by the characterisation of a human enamel TEM sample and the subsequent comparison of the results to high resolution TEM imaging. The TKD - pattern matching approach measures the full HAp crystallographic orientation enabling a quantitative measurement of not just the c-axis orientations, but also the extent of any rotation of the crystal lattice about the c-axis, between and within grains. Results presented here show how this additional information highlights potentially significant aspects of the HAp crystallite structure, including intra-crystallite distortion and the presence of multiple high angle boundaries between adjacent crystallites with rotations about the c-axis. These and other observations enable a more rigorous understanding of the relationship between HAp structures and the physical properties of dental enamel.
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Affiliation(s)
- Patrick Trimby
- Oxford Instruments Nanoanalysis, High Wycombe, Buckinghamshire, UK; Carl Zeiss Ltd., Cambourne, Cambridge, UK.
| | | | - Maisoon Al-Jawad
- School of Dentistry, University of Leeds, Leeds, West Yorkshire, UK
| | - Stuart Micklethwaite
- School of Chemical and Process Engineering, University of Leeds, Leeds, West Yorkshire, UK
| | - Zabeada Aslam
- School of Chemical and Process Engineering, University of Leeds, Leeds, West Yorkshire, UK
| | | | - Sandra Piazolo
- School of Earth and Environment, University of Leeds, Leeds, West Yorkshire, UK
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Shohel M, Ray KK, Tivanski AV, McAdams NEB, Bancroft AM, Cramer BD, Forbes TZ. Nanomechanical variability in the early evolution of vertebrate dentition. Sci Rep 2022; 12:10203. [PMID: 35715512 PMCID: PMC9205932 DOI: 10.1038/s41598-022-14157-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 06/02/2022] [Indexed: 01/28/2023] Open
Abstract
Conodonts are an extinct group of primitive jawless vertebrates whose elements represent the earliest examples of a mineralized feeding apparatus in vertebrates. Their relative relationship within vertebrates remains unresolved. As teeth, conodont elements are not homologous with the dentition of vertebrates, but they exhibit similarities in mineralization, growth patterns, and function. They clearly represent an early evolutionary experiment in mineralized dentition and offer insight into analogous dentition in other groups. Unfortunately, analysis of functional performance has been limited to a handful of derived morphologies and material properties that may inform ecology and functional analysis are virtually unknown. Here we applied a nanoscale approach to evaluate material properties of conodont bioapatite by utilizing Atomic Force Microscopy (AFM) nanoindentation to determine Young's modulus (E) along multiple elements representing different ontogenetic stages of development in the coniform-bearing apparatus of Dapsilodus obliquicostatus. We observed extreme and systematic variation in E along the length (oral to aboral) of each element that largely mirrors the spatial and ontogenetic variability in the crystalline structure of these specimens. Extreme spatial variability of E likely contributed to breakage of elements that were regularly repaired/regrown in conodonts but later vertebrate dentition strategies that lacked the ability to repair/regrow likely required the development of different material properties to avoid structural failure.
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Affiliation(s)
- Mohammad Shohel
- grid.214572.70000 0004 1936 8294Department of Chemistry, University of Iowa, Iowa City, IA 52242 USA
| | - Kamal K. Ray
- grid.214572.70000 0004 1936 8294Department of Chemistry, University of Iowa, Iowa City, IA 52242 USA
| | - Alexei V. Tivanski
- grid.214572.70000 0004 1936 8294Department of Chemistry, University of Iowa, Iowa City, IA 52242 USA
| | - Neo E. B. McAdams
- grid.264784.b0000 0001 2186 7496Department of Geosciences, Texas Tech University, Lubbock, TX 79409 USA
| | - Alyssa M. Bancroft
- grid.214572.70000 0004 1936 8294Iowa Geological Survey, University of Iowa, Iowa City, IA 52242 USA
| | - Bradley D. Cramer
- grid.214572.70000 0004 1936 8294Department of Earth and Environmental Sciences, University of Iowa, Iowa City, IA 52242 USA
| | - Tori Z. Forbes
- grid.214572.70000 0004 1936 8294Department of Chemistry, University of Iowa, Iowa City, IA 52242 USA
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