Dental enamel structure in long-nosed armadillos (Xenarthra: Dasypus) and its evolutionary implications
| Autor: | Mariela C. Castro, Emma Carolina Vieytes, Alfredo Armando Carlini, Martín Ricardo Ciancio |
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| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
0303 health sciences Dental enamel Zoology Xenarthra Biology biology.organism_classification 010603 evolutionary biology 01 natural sciences stomatognathic diseases 03 medical and health sciences stomatognathic system Animal Science and Zoology Dasypus Long-nosed armadillos Ecology Evolution Behavior and Systematics 030304 developmental biology |
| Zdroj: | Zoological Journal of the Linnean Society. 192:1237-1252 |
| ISSN: | 1096-3642 0024-4082 |
| Popis: | Most xenarthrans have a reduced and simplified dentition that lacks enamel. However, the presence of prismatic enamel has been recorded in the Eocene armadillos Utaetus buccatus (Euphractinae) and Astegotherium dichotomus (Astegotheriini). Among extant xenarthrans, the occurrence of enamel has been recognized only in the long-nosed armadillo, Dasypus novemcinctus (Dasypodinae), but its microstructure has never been described. In this contribution, we analyse the enamel microstructure in deciduous and permanent teeth of four Dasypus species. In deciduous molariform teeth of some species, we identify an apical cap of vestigial enamel (without crystalline structure), interpreted as an amorphous ameloblastic secretion. In permanent teeth, a thin layer of true enamel is found in the apical portion of unworn molariforms. The enamel is prismatic in D. novemcinctus, but in Dasypus hybridus, Dasypus sabanicola and Dasypus punctatus it is prismless. Taking into account the Eocene species of armadillos, the ancestral condition of enamel in cingulates could have been more complex (as in other placentals) and undergone progressive reduction, as shown in the Dasypus lineage. In light of previous genetic and developmental studies, we review and briefly discuss the processes that can account for the reduction/loss of enamel in extant and extinct armadillos. The retention of enamel and the fact that this genus is the only living xenarthran with two functional generations of teeth support the early divergence of the Dasypus lineage among living cingulates. This is in agreement with morphological and molecular analyses. |
| Databáze: | OpenAIRE |
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