INVESTIGADORES
VIZCAINO Sergio Fabian
artículos
Título:
The teeth of the toothless. Novelties and key innovations in the evolution of xenarthrans (Mammalia, Xenarthra)
Autor/es:
VIZCAÍNO S. F.
Revista:
PALEOBIOLOGY
Editorial:
PALEONTOLOGICAL SOC INC
Referencias:
Año: 2009 vol. 35 p. 343 - 366
ISSN:
0094-8373
Resumen:
A combination of historical, functional, and biomechanical constraints has shaped the
masticatory apparatus of fossil and extant xenarthrans. Among the more notable features are the teeth:
hypselodont; commonly reduced in size, complexity, and number; separated by short diastema; and
composed of osteodentine. Enamel is absent, as are the cuspal patterns of other mammals. A
comprehensive revision of teeth and other features of the masticatory apparatus of xenarthrans reveals
that previous generalizations underestimate the morphological diversity and adaptive possibilities
developed within the clade. The great diversity of forms suggests several such possibilities ranging
from specialized myrmecophagous species to carrion feeders or predators among animalivores;
selective browsers to bulk grazers among herbivores; and omnivores. In some cases xenarthrans
represent less extreme versions of patterns developed in other major clades of mammals (marsupials,
afrotheres, euarchontoglires, and laurasiatheres) clearly predetermined by a tribosphenic dental
morphology, whereas in others they represent unique novelties indicative of particular biological roles.
The combination of tooth features that characterize xenarthrans might be seen as the key innovation for
the ecologic diversity developed at least since the Oligocene, breaking the mold of the tribosphenic
condition that constrained the evolution of the other major clades of mammals.