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.l...@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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