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Shark Teeth (shark + tooth)
Selected AbstractsEnameloid microstructure in the oldest known chondrichthyan teethACTA ZOOLOGICA, Issue 2009H. Botella Abstract Previous studies on tooth enameloid microstructure in several chondrichthyan taxa spanning the phylogeny of the group provided support for the homology of chondrichthyan tooth enameloid. This hypothesis requires that a single crystallite enameloid (SCE) monolayer must be present in the teeth of the most primitive chondrichthyan. However, the dental microstructure of the earliest sharks has yet to be investigated. We have studied the tooth enameloid microstructure of the two oldest tooth-bearing shark species currently known, Leonodus carlsi Mader (1986) and Celtiberina maderi Wang (1993), from the lowermost Lochkovian (Lower Devonian) of Spain. Our study demonstrates the presence of a SCE monolayer in the teeth of both species. These results show that a superficial cap of SCE is present in the oldest shark teeth known, which suggest its presence in the most basal chondrichthyans. [source] « Un chef est un requin qui voyage par terre » : fonctions et statuts des armatures de projectile en dent de Carcharhinus leucas et aiguillon caudal de raie dans l'Arabie des VIe-IIIe millénaires av. notre èreARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 1 2009Vincent Charpentier During the Neolithic and Early Bronze Age, many teeth of large sharks (Carcharhinus leucas) and stingray spines were transformed into projectile points in south-eastern Arabia. These points were probably used for fishing. Deriving from dangerous and/or toxic animals, shark teeth and stingray spines were certainly markers of prestige. [source] Performance of shark teeth during puncture and draw: implications for the mechanics of cuttingBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010LISA B. WHITENACK The performance of an organism's feeding apparatus has obvious implications for its fitness and survival. However, the majority of studies that focus on chondrichthyan feeding have largely ignored the role of teeth. Studying the functional morphology of shark teeth not only elucidates the biological role that teeth play in feeding, but also provides insight specifically into the evolution of shark feeding because teeth are often the only structures available in the fossil record. In the present study, we investigate the puncture and draw performance of three general categories of extant teeth, tearing-type, cutting-type, and cutting,clutching type, as well as three fossil morphologies, utilizing a universal testing system. Differences in puncturing performance occurred among different prey items, indicating that not all ,soft' prey items are alike. The majority of teeth were able to puncture different prey items, and differences in puncture performance also occurred among tooth types; however, few patterns emerged. In some cases, broader triangular teeth were less effective at puncturing than narrow-cusped teeth. There were no differences between the maximum draw forces and maximum puncture forces. Many of the shark teeth in the present study were not only able to perform draw and puncture equally well, but also many tooth morphologies were functionally equivalent to each other. The findings obtained in the present study lend little support to the belief that shark tooth morphology is a good predictor of biological role. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 271,286. [source] | ||||||||||