Dental development and first premolar homology in placental mammals

Vertebrate Zoology

article

Calum J. McKay¹  Claudia Welbourn-Green¹  Erik R. Seiffert²  Hesham Sallam³  Jessica Li¹  Sophia E. Kakarala⁴  Nigel C. Bennett⁵  Robert J. Asher¹ 

[1] University of Cambridge;University of Southern California;American University in Cairo;Weill Cornell Medicine;University of Pretoria

关键词: Afrotheria;    canids;    Carnivora;    deciduous teeth;    dogs;    macroscelidids;    ontogeny;    tooth replacement;    sengis;   

DOI  :  10.3897/vz.72.e78234

学科分类：社会科学、人文和艺术（综合）

来源: Pensoft

【 摘 要 】

Macroscelidid afrotherians and canid carnivorans possess four premolar loci, the first of which is not replaced. Previous work suggests that the first premolar in macroscelidids is a retained deciduous tooth, but in Canis it is a successional tooth with no milk precursor. We tested this contrasting interpretation of first premolar homology with data from ontogenetic anatomy and with area predictions from the inhibitory cascade (IC) model. Our results based on anatomy support previous interpretations that the functional first premolar is a retained deciduous tooth (dp1) with no successor in macroscelidids, and a successional tooth (p1) with no precursor in Canis. Hyracoids are among the few placental mammals that show replacement at the first premolar locus and show less deviation than other taxa of actual from predicted areas across the deciduous and molar toothrow. However, predicted vs. actual tooth areas can depart substantially from one another. At least without a better means of representing tooth size, the inhibitory cascade does not help to distinguish the deciduous from successional first premolar. This observation does not rule out the possibility that factors such as a size-shift within the toothrow (e.g., carnivoran carnassials) help to explain deviations from the inhibitory cascade model.

【 授权许可】

CC BY