DearMARMAM subscribers,
Weare pleased to announce the publication of the following paper in the
currentissue of The Science of Nature:
Enamel ultrastructure of fossil and modern pinnipeds: evaluating hypothesesof
feeding adaptations in the extinct walrus Pelagiarctos
CarolinaLoch, Robert Boessenecker, Morgan Churchill and Jules A. Kieser
doi:10.1007/s00114-016-1366-z
Volume103(44), May 2016, Pages 1-8
Abstract
This study aimed to assess the enamelultrastructure in modern otariid pinnipeds
and in the extinct walrus Pelagiarctos. Teeth of the New Zealandfur seal
(Arctocephalus forsteri),sea lion (Phocarctos hookeri), and Pelagiarctos
thomasi were embedded,sectioned, etched and analyzed via scanning electron
microscopy. The enamel ofNZ otariids and Pelagiarctos was prismatic and
moderately thick, measuring150-450 µm on average. It consisted of transversely
oriented Hunter-Schregerbands (HSB) from the enamel-dentine junction (EDJ) to
near the outer surface,where it faded into prismless enamel less than 10 µm
thick. The width of HSBwas variable and averaged between 6-10 prisms, and they
presented an undulatingcourse both in longitudinal and cross sections. The
overall organization of theenamel was similar in all teeth sampled; however,
the enamel was thicker incanines and postcanines than in incisors. The crowns
of all teeth sampled wereuniformly covered by enamel; however, the grooved
incisors lacked an enamelcover on the posterior side of the buccal face. Large
tubules and tuft-likestructures were seen at the EDJ. HSB enamel as well as
tubules and tufts at theEDJ suggest increased occlusal loads during feeding, a
biomechanical adaptationto avoid enamel cracking and failure. Despite overall
simplification in toothmorphology and reduced mastication, the fossil and
modern pinnipeds analyzedhere retained the complex undulating HSB structure of
other fossil and living Carnivora,while other marine mammals such as cetaceans
developed simplified radialenamel.
Full text is available at:
http://link.springer.com/article/10.1007/s00114-016-1366-z
Or alternatively, a pdf can be requested at:[email protected]
________________________________________
Carolina Loch Silva, PhD
Research Fellow
Sir John Walsh Research Institute
Faculty of Dentistry, University of Otago
Dunedin 9054, New Zealand
Phone: +(64) 03 479-9073
&
Research Collaborator
Geology Department, University of Otago
and
Laboratório de Mamíferos Aquáticos UFSC
Florianópolis, SC - Brasil
http://www.otago.ac.nz/sjwri/people/craniofacial-biomechanics/otago054438.html
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