[MARMAM] New paper on enamel and dentine ultrastructure in dolphins

[Carolina Loch]

Dear MARMAM subscribers,
 

We are pleased to announce the publication of the following paper in the current issue of Zoomorphology:



Ultrastructure of enamel and dentine in extant dolphins (Cetacea: Delphinoidea and Inioidea)


Carolina Loch,  Warwick Duncan, Paulo C. Simões-Lopes, Jules A. Kieser and R. Ewan Fordyce 





doi:10.1007/s00435-012-0180-1


Volume 132, Issue 2, April 2013, Pages 215-225



Abstract
            
              
                            
                            Longitudinal and 
cross sections of teeth from 17 species of the Recent dolphins 
(Delphinoidea and Inioidea) were examined under scanning electron 
microscope to study the arrangement and ultrastructure of dental tissues
 with reference to phylogenetic and functional constraints. For most 
species, enamel had a simple bi-layered structure of radial enamel and 
an outer layer of prismless enamel. The outer prismless layer varied 
from 5 to 30 % of enamel thickness. The enamel of Burmeister’s porpoise (Phocoena spinipinnis)
 was entirely prismless. The prisms had an open sheath; tubules and 
tuft-like structures were common at the enamel-dentine junction. 
Cetacean dentine was characterized by irregularly distributed dentinal 
tubules in a relatively homogenous dentinal matrix. Radial enamel was 
observed in all Delphinoidea and in the franciscana (Pontoporia blainvillei), whereas the Amazon river dolphin (Inia geoffrensis)
 had prisms organized in Hunter–Schreger bands. HSB in enamel are 
regarded as a device for resisting propagation of cracks. These may 
occur due to increased functional demands, possibly related to the 
hardness of the species diet. Simplification in tooth shape and reduced 
biomechanical demands plausibly explain the primitive radial 
organization among delphinoids and Pontoporia.
 The HSB structure in the Amazon river dolphin, similar to those of 
extinct archaeocetes, seems to have secondary functional implications. 
However, the distribution of HSB in more-basal odontocetes is too poorly
 known to judge whether the HSB of Inia are a retained plesiomorphic feature or convergence.
                          
            



Full text is available at:
http://link.springer.com/article/10.1007%2Fs00435-012-0180-1



Or alternatively, a pdf can be requested at: carolina.loch at otago.ac.nz 



Best regards,

MSc. Carolina Loch Silva 
PhD Candidate
Geology Department, University of Otago
Dunedin 9054, New Zealand
http://www.otago.ac.nz/geology/people/students/loch/index.html
&
Laboratório de Mamíferos Aquáticos UFSCFlorianópolis, SC - Brasil 
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