Dataset Information

Ontogenetic variability in crystallography and mosaicity of conodont apatite: implications for microstructure, palaeothermometry and geochemistry.

ABSTRACT: X-ray diffraction data from Silurian conodonts belonging to various developmental stages of the species Dapsilodus obliquicostatus demonstrate changes in crystallography and degree of nanocrystallite ordering (mosaicity) in both lamellar crown tissue and white matter. The exclusive use of a single species in this study, combined with systematic testing of each element type at multiple locations, provided insight into microstructural and crystallographic differentiation between element type (Sa , Sb -c , M) as well as between juveniles and adults. A relative increase in the unit cell dimensions a/c ratio of nanocrystallites during growth was apparent in areas demonstrating single-crystal behaviour, but no such relationship was seen in dominantly polycrystalline areas. Systematic variations in mosaicity were identified, with mosaicity (as a proxy for disorder) increasing during growth, as well as along elements from tip to base. These results provide potential insight into the integrity of conodont apatite as a recorder of palaeoseawater chemistry, as well as demonstrate the need to consider the influence of ontogeny and element type on the use of conodonts in palaeothermometry and geochemical investigations.

SUBMITTER: Shohel M

PROVIDER: S-EPMC7428274 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Ontogenetic variability in crystallography and mosaicity of conodont apatite: implications for microstructure, palaeothermometry and geochemistry.

Shohel Mohammad M McAdams Neo E B NEB Cramer Bradley D BD Forbes Tori Z TZ

Royal Society open science 20200708 7

X-ray diffraction data from Silurian conodonts belonging to various developmental stages of the species <i>Dapsilodus obliquicostatus</i> demonstrate changes in crystallography and degree of nanocrystallite ordering (mosaicity) in both lamellar crown tissue and white matter. The exclusive use of a single species in this study, combined with systematic testing of each element type at multiple locations, provided insight into microstructural and crystallographic differentiation between element typ ...[more]

PMID: 32874630

Similar Datasets

Project description:Testudines are a group of reptiles characterized by the presence of a shell covered by keratinous shields. Stigmochelys pardalis is the most widely distributed terrestrial testudine in southern Africa. Although relatively common with some life history traits being well known, the growth of this species has yet to be studied in any detail. The bone microanatomy of this clade differs from that found in other amniotes, where terrestrial species tend to display characteristics normally seen in aquatic species and vice versa. A detailed histological analysis of the limb bones of S. pardalis reveals extensive variation through ontogeny. Cortical bone becomes increasingly thicker through ontogeny and is finally resorbed in the late sub-adult stage, resulting in a thin cortex and a large infilled medullary cavity. The predominant bone tissues are parallel-fibred and lamellar-zonal for the forelimbs and hind limbs respectively. The oldest individual displayed an External Fundamental System indicating that the growth rate had decreased substantially by this stage. Variability is prevalent between the forelimb and hind limb as well as between early and late sub-adults Forelimb elements exhibit characteristics such as faster growing parallel-fibered bone tissue, slightly higher vascularization and a predominance of annuli over Lines of Arrested Growth (LAG) compared to the hind limb which exhibits poorly vascularized, slower growing lamellar-zonal bone interrupted by LAGs. These differences indicate that the forelimb grew more rapidly than the hind limb, possibly due to the method of locomotion seen in terrestrial species. The extensive bone resorption that occurs from the early sub-adult stage destroys much of the primary cortex and results in a significantly different ratio of inner and outer bone diameter (p = 3.59 × 10--5; df = 28.04) as well as compactness (p = 2.91 × 10--5; df = 31.27) between early and late sub-adults. The extensive bone resorption seen also destroys the ecological signal and infers an aquatic lifestyle for this species despite it being clearly terrestrial. This supports the results of other studies that have found that using bone microanatomy to determine lifestyle in testudines does not produce accurate results.

Dataset Information

Ontogenetic variability in crystallography and mosaicity of conodont apatite: implications for microstructure, palaeothermometry and geochemistry.

Publications

Ontogenetic variability in crystallography and mosaicity of conodont apatite: implications for microstructure, palaeothermometry and geochemistry.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets