Crystallography of craniid brachiopods by electron backscatter diffraction (EBSD)

Pérez‐Huerta, Alberto; England, Jennifer; Cusack, Maggie

doi:10.1017/s1755691007079832

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…Why they retain the orientation of the underlying foliated-like sublayer can be explained by epitaxial growth. Evidence of crystal continuity across laminae (indicative of epitaxy) was presented in the seminacre of Novocrania . , This effect may be enhanced by the fact that spiral growth is the most common mode, nucleation events (which increase the probability of errors) being rare (see also Williams et al).…”

Section: Discussionmentioning

confidence: 99%

Crystallography of the Calcitic Foliated-Like and Seminacre Microstructures of the Brachiopod Novocrania

Checa

Gaspard

González-Segura

et al. 2009

Crystal Growth & Design

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Previous studies on the calcitic seminacre of the craniid brachiopod NoVocrania have never fully resolved the crystallography of its constituent calcite crystals. With this aim, we studied the tablets forming the foliated-like and seminacre layers of this brachiopod by means of scanning electron microscopy coupled to electron backscatter diffraction. In both cases, tablets are monocrystalline and have a common crystallographic structure. Their c axes lie approximately parallel to the shell surface, and, for those tablets forming the internal shell ribs, they are also parallel to the rib elongation. There is no consistency in the orientation of the a axes in the different plates. Crystal competition processes appear to be responsible for this fiber texture. The tablets are bounded by planar rhombohedral faces. The main, innermost surface is not a crystal face but marks the boundary of the crystal with the mantle epithelium. Our data also show that, during spiral growth, the crystal axes of seminacre tablets remain stationary. Calcite twins occasionally develop in the species NoVocrania anomala. The foliated-like and seminacre microstructures are crystallographically dissimilar to the foliated layer of molluscs but similar to the foliated layer of bryozoans. The relationship of brachiopod seminacre to the molluscan nacre is also discussed.

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Section: Discussionmentioning

confidence: 99%

Crystallography of the Calcitic Foliated-Like and Seminacre Microstructures of the Brachiopod Novocrania

Checa

Gaspard

González-Segura

et al. 2009

Crystal Growth & Design

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“…Continuity of crystallographic pattern across skeletal layers occurs in calcitic and aragonitic microfabrics. 32 The co-alignment of <0001> and <10-14 > axes suggests a highly ordered sheet structuring. 33 We conclude that Corumbella skeleton is now formed by replacive sparry calcite crystals of a probably original laminar microstructure of aragonite.…”

Section: Discussionmentioning

confidence: 99%

Ediacaran Corumbella has a cataphract calcareous skeleton with controlled biomineralization

Osés¹,

Wood²,

Romero³

et al. 2022

iScience

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“…The crystallography in the context of shell ultrastructure of recent species of craniid brachiopods has been previously analysed and it is well understood (England et al . 2007; Pérez‐Huerta et al . in press).…”

Section: Crystallography In Recent Craniid Brachiopodsmentioning

confidence: 99%

“…These laminae consist of calcite tablets that grow by single or double screw dislocation (see England et al . 2007; Pérez‐Huerta et al . in press).…”

Section: Crystallography In Recent Craniid Brachiopodsmentioning

confidence: 99%

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Crystallography and Diagenesis in Fossil Craniid Brachiopods

2007

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One of the fundamental questions in biomineralization is how organisms control crystallographic orientation during biomineral production. The understanding of how diagenetic changes influence the preservation of original crystallographic patterns in fossilized biomineral structures provides a priori fundamental information for such an assessment. Fossil craniid brachiopods Petrocrania scabiosa (Late Ordovician) and Crania craniolaris (Late Cretaceous) are analysed using electron backscattered diffraction (EBSD) to provide crystallographic data at high spatial resolution in the structural context. EBSD analyses show that P. scabiosa maintains most of the original crystallographic signature, including data from individual calcite tablets and laminae, while C. craniolaris only retains fragmentary crystallographic data reflecting the crystallographic continuity of tablets across laminae. Data show that the preservation of the original crystallographic signature is independent of that of shell ultrastructure and geological time. In addition, results allow us to propose a series of steps in the evolution of 'crystallographic loss' due to diagenesis.

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Crystallography of craniid brachiopods by electron backscatter diffraction (EBSD)

Cited by 6 publications

References 13 publications

Crystallography of the Calcitic Foliated-Like and Seminacre Microstructures of the Brachiopod Novocrania

Crystallography of the Calcitic Foliated-Like and Seminacre Microstructures of the Brachiopod Novocrania

Ediacaran Corumbella has a cataphract calcareous skeleton with controlled biomineralization

Crystallography and Diagenesis in Fossil Craniid Brachiopods

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