62 research outputs found
Preliminary observations on the bone histology of the Middle Triassic pseudosuchian archosaur Batrachotomus kupferzellensis
Fine-scale genetic analysis of the exploited Nile monitor (Varanus niloticus) in Sahelian Africa
A mineralogical study in contrasts: highly mineralized whale rostrum and human enamel
The outermost enamel of the human tooth and the rostrum of the whale Mesoplodon densirostris
are two highly mineralized tissues that contain over 95wt.% mineral, i.e., bioapatite. However,
the same mineral type (carbonated hydroxylapatite) does not yield the same material properties,
as revealed by Raman spectroscopy, scanning electron microscopy, electron microprobe analysis,
and synchrotron X-ray diffraction analysis. Overall, the outermost enamel of a tooth has more
homogeneous physical and chemical features than the rostrum. Chemical comparison of rostrum
and enamel shows bioapatite in the rostrum to be enriched in Na, Mg, CO3, and S, whereas the
outermost enamel shows only a slightly enriched Cl concentration. Morphologically, mineral rods
(at tens of μm scale), crystallites and prisms (at μm and sub-μm scale), and platelets (at tens of nm
scale) all demonstrate less organized texture in the rostrum than in enamel. Such contrasts between
two mineralized tissues suggest distinct pathways of biomineralization, e.g., the nature of the
equilibrium between mineral and body fluid. This study illustrates the remarkable flexibility of the
apatite mineral structure to match its chemical and physical properties to specific biological needs
within the same animal or between species.The work was partially funded by NIH grant 1R21AR055184-01A2 and SRF for ROCS, SEM
Bizarre fossil beaked whales (Odontoceti, Ziphiidae) fished from the Atlantic Ocean floor off the Iberian Peninsula
Croissance et morphologenese postnatales de la mandibule du vison (Mustela vison Schreiber) : donnees sur la dynamique et l'interpretation fonctionnelle des depots osseux mandibulaires.
National audienc
Présence d'un tissu similaire à l'émail, l'ostéodermine, sur les ostéodermes d'un lézard Glytosaurinae (Anguidea)
Vascularization in Ornamented Osteoderms: Physiological Implications in Ectothermy and Amphibious Lifestyle in the Crocodylomorphs?
International audienc
The evolution of bone ornamentation in Pseudosuchia: morphological constraints versus ecological adaptation
International audienc
An enamel-like tissue, osteodermine, on the osteoderms of a fossil anguid (Glyptosaurinae) lizard
International audienceThe Glyptosaurinae, a fossil clade of anguid lizards, have robust osteoderms, with a granular ornamentation consisting of tubercles. In this study, the structural and histological features of these osteoderms are described in order to reconstruct their developmental pattern and further document the possible homology that could exist between vertebrate integumentary skeletons. Glyptosaurine osteoderms display a diploe architecture and an unusually complex structure that includes four tissue types: an intensely remodeled core of woven-fibered bone, a thick basal layer of lamellar bone, a peripheral ring exhibiting histological features intermediate between these two tissues and containing dense bundles of long Sharpey fibers, and a superficial layer made of a monorefringent, acellular and highly mineralized material, different from bone, and comparable in many respects to hypermineralized tissues such as ganoine, enameloids and enamel. We call this tissue osteodermine. The growth pattern of glyptosaurine osteoderms is likely to have involved first metaplasia, at an early developmental stage, then appositional growth due to osteoblast activity. The superficial layer that is well developed at the tubercle level must have resulted from epidermal and dermal contributions, a conclusion that would support previous hypotheses on the role of epidermal-dermal interactions in the formation of squamate osteoderms. (C) 2011 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved
Inner architecture of vertebral centra in terrestrial and aquatic mammals: A two-dimensionnal comparative study
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