title: Developmental and evolutionary novelty in the serrated teeth of theropod dinosaurs.
abstract: Tooth morphology and development can provide valuable insights into the feeding behaviour and evolution of extinct organisms. The teeth of Theropoda, the only clade of predominantly predatory dinosaurs, are characterized by ziphodonty, the presence of serrations (denticles) on their cutting edges. Known today only in varanid lizards, ziphodonty is much more pervasive in the fossil record. Here we present the first model for the development of ziphodont teeth in theropods through histological, SEM, and SR-FTIR analyses, revealing that structures previously hypothesized to prevent tooth breakage instead first evolved to shape and maintain the characteristic denticles through the life of the tooth. We show that this novel complex of dental morphology and tissues characterizes Theropoda, with the exception of species with modified feeding behaviours, suggesting that these characters are important for facilitating the hypercarnivorous diet of most theropods. This adaptation may have played an important role in the initial radiation and subsequent success of theropods as terrestrial apex predators.
authors.affiliation: 1] Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada [2] Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. Toronto, Ontario, M5S 3B2, Canada.
authors.forename: K S
authors.initials: KS
authors.lastname: Brink
authors.affiliation: 1] Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada [2] Department of Optics and Photonics, National Central University, Jhongli City, Taoyuan 32001, Taiwan.
authors.forename: R R
authors.initials: RR
authors.lastname: Reisz
authors.affiliation: 1] Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada [2] Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. Toronto, Ontario, M5S 3B2, Canada.
authors.forename: A R H
authors.initials: AR
authors.lastname: LeBlanc
authors.affiliation: Department of Optics and Photonics, National Central University, Jhongli City, Taoyuan 32001, Taiwan.
authors.forename: R S
authors.initials: RS
authors.lastname: Chang
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan.
authors.forename: Y C
authors.initials: YC
authors.lastname: Lee
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan.
authors.forename: C C
authors.initials: CC
authors.lastname: Chiang
authors.affiliation: 1] Department of Optics and Photonics, National Central University, Jhongli City, Taoyuan 32001, Taiwan [2] National Chung Hsing University, Taichung City 402, Taiwan.
authors.forename: T
authors.initials: T
authors.lastname: Huang
authors.affiliation: 1] Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. Toronto, Ontario, M5S 3B2, Canada [2] Royal Ontario Museum, 100 Queens Park, Toronto, Ontario, M5S 2C6, Canada.
authors.forename: D C
authors.initials: DC
authors.lastname: Evans
mesh_terms: D000818:Animals; D005075:Biological Evolution; D025061:Dinosaurs; D017550:Spectroscopy, Fourier Transform Infrared; D014070:Tooth / Q000033:anatomy & histology*