title: Evolutionary and biological implications of dental mesial drift in rodents: the case of the Ctenodactylidae (Rodentia, Mammalia).
abstract: Dental characters are importantly used for reconstructing the evolutionary history of mammals, because teeth represent the most abundant material available for the fossil species. However, the characteristics of dental renewal are presently poorly used, probably because dental formulae are frequently not properly established, whereas they could be of high interest for evolutionary and developmental issues. One of the oldest rodent families, the Ctenodactylidae, is intriguing in having longstanding disputed dental formulae. Here, we investigated 70 skulls among all extant ctenodactylid genera (Ctenodactylus, Felovia, Massoutiera and Pectinator) by using X-ray conventional and synchrotron microtomography in order to solve and discuss these dental issues. Our study clearly indicates that Massoutiera, Felovia and Ctenodactylus differ from Pectinator not only by a more derived dentition, but also by a more derived eruptive sequence. In addition to molars, their dentition only includes the fourth deciduous premolars, and no longer bears permanent premolars, conversely to Pectinator. Moreover, we found that these premolars are lost during adulthood, because of mesial drift of molars. Mesial drift is a striking mechanism involving migration of teeth allowed by both bone remodeling and dental resorption. This dental innovation is to date poorly known in rodents, since it is only the second report described. Interestingly, we noted that dental drift in rodents is always associated with high-crowned teeth favoring molar size enlargement. It can thus represent another adaptation to withstand high wear, inasmuch as these rodents inhabit desert environments where dust is abundant. A more accurate study of mesial drift in rodents would be very promising from evolutionary, biological and orthodontic points of view.
authors.affiliation: Team Evo-Devo of Vertebrate Dentition, Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242 Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France.
authors.forename: Helder
authors.initials: H
authors.lastname: Gomes Rodrigues
authors.forename: Floréal
authors.initials: F
authors.lastname: Solé
authors.forename: Cyril
authors.initials: C
authors.lastname: Charles
authors.forename: Paul
authors.initials: P
authors.lastname: Tafforeau
authors.forename: Monique
authors.initials: M
authors.lastname: Vianey-Liaud
authors.forename: Laurent
authors.initials: L
authors.lastname: Viriot
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001641:Bicuspid / Q000033:anatomy & histology*; D005075:Biological Evolution; D053476:Extinction, Biological; D005580:Fossils; D008644:Mesial Movement of Teeth; D008963:Molar / Q000033:anatomy & histology*; D012377:Rodentia / Q000033:anatomy & histology* / Q000502:physiology; D017356:Synchrotrons; D014056:Tomography, X-Ray; D019228:Tooth Crown / Q000033:anatomy & histology*