title: Brief communication: Contributions of enamel-dentine junction shape and enamel deposition to primate molar crown complexity.
abstract: Molar crown morphology varies among primates from relatively simple in some taxa to more complex in others, with such variability having both functional and taxonomic significance. In addition to the primary cusps, crown surface complexity derives from the presence of crests, cuspules, and crenulations. Developmentally, this complexity results from the deposition of an enamel cap over a basement membrane (the morphology of which is preserved as the enamel-dentine junction, or EDJ, in fully formed teeth). However, the relative contribution of the enamel cap and the EDJ to molar crown complexity is poorly characterized. In this study we examine the complexity of the EDJ and enamel surface of a broad sample of primate (including fossil hominin) lower molars through the application of micro-computed tomography and dental topographic analysis. Surface complexity of the EDJ and outer enamel surface (OES) is quantified by first mapping, and then summing, the total number of discrete surface orientation patches. We investigate the relative contribution of the EDJ and enamel cap to crown complexity by assessing the correlation in patch counts between the EDJ and OES within taxa and within individual teeth. We identify three patterns of EDJ/OES complexity which demonstrate that both crown patterning early in development and the subsequent deposition of the enamel cap contribute to overall crown complexity in primates.
authors.affiliation: Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany. skinner@eva.mpg.de
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Skinner
authors.forename: Alistair
authors.initials: A
authors.lastname: Evans
authors.forename: Tanya
authors.initials: T
authors.lastname: Smith
authors.forename: Jukka
authors.initials: J
authors.lastname: Jernvall
authors.forename: Paul
authors.initials: P
authors.lastname: Tafforeau
authors.forename: Kornelius
authors.initials: K
authors.lastname: Kupczik
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Olejniczak
authors.forename: Antonio
authors.initials: A
authors.lastname: Rosas
authors.forename: Jakov
authors.initials: J
authors.lastname: Radovcić
authors.forename: J Francis
authors.initials: JF
authors.lastname: Thackeray
authors.forename: Michel
authors.initials: M
authors.lastname: Toussaint
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Hublin
mesh_terms: D000818:Animals; D002521:Cercopithecus / Q000033:anatomy & histology; D003743:Dental Enamel / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D003804:Dentin / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D002679:Pan troglodytes / Q000033:anatomy & histology; D053820:Pitheciidae / Q000033:anatomy & histology; D057079:Pongo / Q000033:anatomy & histology; D011323:Primates / Q000033:anatomy & histology*; D013499:Surface Properties; D019237:Tooth Cervix / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D019228:Tooth Crown / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography