[MARMAM] New paper on enamel ultrastructure in pinnipeds

Carolina Loch carolinaloch at yahoo.com.br
Mon May 16 20:33:26 PDT 2016


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:carolina.loch at otago.ac.nz 


 ________________________________________
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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