Development and microstructure of tooth histotypes in the blue shark, Prionace glauca (Carcharhiniformes: Carcharhinidae) and the great white shark, Carcharodon carcharias (Lamniformes: Lamnidae)

Abstract

Elasmobranchs exhibit two distinct arrangements of mineralized tissues in the teeth that are known as orthodont and osteodont histotypes. Traditionally, it has been said that orthodont teeth maintain a pulp cavity throughout tooth development whereas osteodont teeth are filled with osteodentine and lack a pulp cavity when fully developed. We used light microscopy, scanning electron microscopy, and high-resolution micro-computed tomography to compare the structure and development of elasmobranch teeth representing the two histotypes. As an example of the orthodont histotype, we studied teeth of the blue shark, Prionace glauca (Carcharhiniformes: Carcharhinidae). For the osteodont histotype, we studied teeth of the great white shark, Carcharodon carcharias (Lamniformes: Lamnidae). We document similarities and differences in tooth development and the microstructure of tissues in these two species and review the history of definitions and interpretations of elasmobranch tooth histotypes. We discuss a possible correlation between tooth histotype and tooth replacement and review the history of histotype differentiation in sharks. We find that contrary to a long held misconception, there is no orthodentine in the osteodont teeth of C. carcharias.

Identification of Shark Teeth (Elasmobranchii: Lamnidae) from a Historic Fishing Station on Smuttynose Island, Maine, Using Computed Tomography Imaging

“…Moyer et al (2015) observed in developing teeth of the White Shark that osteodentine filling the inside of the crown is less dense than it is in fully developed teeth owing to the tissue's incomplete mineralization. The lowdensity osteodentine core of USM 9000 suggests that this was a developing tooth rather than a functional tooth.…”

“…Figure 7 shows 2 intact lower jaw teeth in Porbeagle specimen CUMV 98002 and the location of characteristic lateral cusplets relative to the central cusp. In their earliest stages of development, shark teeth are composed of a hollow crown made only of enameloid (Moyer et al 2015, Peyer 1968). Therefore, a hollow tooth crown might be recovered from an excavation.…”

“…To understand the presence and prevalence of a particular species of shark at a site, archaeologists must compare isolated and frequently incomplete teeth to descriptions of the morphology of whole teeth (Handley 1996), which can be challenging because most published descriptions are based on more complete material. Recent studies on the tissue arrangement and histology of shark teeth (Moyer et al 2015) provide criteria for identification that can be applied to even incomplete teeth.…”

Tooth Microstructure and Replacement in the Gulper Shark,Centrophorus granulosus(Squaliformes: Centrophoridae)

“…To reference other specific teeth in the dentitions of individual specimens, we assigned each tooth an identifying code based on its location in the jaw and its location in its tooth file following the scheme developed by Moyer et al (2015) and Bemis et al (2015). This scheme is similar to that used by Naylor and Marcus (1994) in that it identifies teeth by position along the jaw; however, we also use numbers to denote a tooth's position within a given tooth file.…”

Modelling tooth–prey interactions in sharks: the importance of dynamic testing

“…The teeth on saw blades are formed by removal of excess metal followed by a polishing or honing step. By contrast, shark teeth develop through deposition of material, with the outer enameloid layer reaching maximum thickness early in development [21]. The cross-section of a saw blade is either wedge shaped or hollow ground, but a shark tooth is a convex structure.…”