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Iguanodontian fossil teeth with replacement of biogenic apatite by aluminium phosphate



Ben Creisler
bcreisler@gmail.com

A new online paper:

Blanca Bauluz, José Manuel Gasca, Miguel Moreno-Azanza andJosé Ignacio
Canudo (2014)
Unusual replacement of biogenic apatite by aluminium phosphate phases
in dinosaur teeth from the Early Cretaceous of Spain.
Lethaia (advance online publication)
DOI: 10.1111/let.12081
http://onlinelibrary.wiley.com/doi/10.1111/let.12081/abstract



Altered iguanodontian dinosaur teeth have been studied to analyse the
unusual replacement of biogenic apatite and to deduce how the
alterations affect the preservation of these fossils. The fossils were
recovered from alluvial lacustrine facies (Barremian, Early
Cretaceous) in Teruel (Spain). Mandibular teeth and sediments were
studied in hand sample, by X-ray diffraction (XRD) and by scanning
electron microscopy (SEM). The combination of the different techniques
shows that the teeth have undergone at least three pseudomorphic
stages: (1) replacement of the organic component of the dentine and
enamel by fluorapatite; (2) replacement of the fluorapatite by
aluminium sulphate phosphate phases (crandallite–woodhouseite series);
and (3) replacement of part of the tooth by gypsum and Al- and Fe-rich
phosphates (vauxite) as a consequence of the superficial weathering of
the fossil-rich outcrop. The presence of organic matter and sulphides
in the host rocks was the main factor promoting the dissolution of the
previous phases and crystallization of the new ones. This is the first
description of the replacement of biogenic apatite in dinosaur teeth
by aluminium and iron phosphates as a result of fossil diagenetic
processes; these minerals are scarce in sedimentary environments and
may have economic interest because they contain rare earth or
radioactive elements. Additionally, our results indicate that, to
ensure proper curating of the specimens from this fossil site, it is
crucial to completely remove the host rock and strictly control
storage humidity.