title: Calcite orientations and composition ranges within teeth across Echinoidea.
abstract: Sea urchin's teeth from four families of order Echinoida and from orders Temnopleuroida, Arbacioida and Cidaroida were studied with synchrotron X-ray diffraction. The high and very high Mg calcite phases of the teeth, i.e. the first and second stage mineral constituents, respectively, have the same crystallographic orientations. The co-orientation of first and second stage mineral, which the authors attribute to epitaxy, extends across the phylogenic width of the extant regular sea urchins and demonstrates that this is a primitive character of this group. The range of compositions Δx for the two phases of Ca1-xMgxCO3 is about 0.20 or greater and is consistent with a common biomineralization process.
authors.affiliation: Department of Molecular Pharmacology and Biological Chemistry, Feinberg School of Medicine, Northwestern University , Chicago, IL , USA and.
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Stock
authors.forename: Konstantin
authors.initials: K
authors.lastname: Ignatiev
authors.forename: Peter L
authors.initials: PL
authors.lastname: Lee
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Almer
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry*; D007091:Image Processing, Computer-Assisted; D012617:Sea Urchins / Q000737:chemistry* / Q000648:ultrastructure; D014070:Tooth / Q000737:chemistry* / Q000648:ultrastructure; D014961:X-Ray Diffraction
chemical_list: D002119:Calcium Carbonate
keywords: Biomineralization; X-ray diffraction; calcite; sea urchin; synchrotron radiation; teeth