Interpretación del molde endocraneano de Eucholoeops fronto, un Megalonychidae (Mammalia, Xenarthra, Tardigrada) del Mioceno temprano de Patagonia (Argentina).

DOZO, MARÍA TERESA

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 1994 vol. 31 p. 317 - 329

0002-7014

The brain of Eucholoeops fronto, an Early Miocene Tardigrada from Patagonia, is studied. This is the first paleoneurologic study of an extinct Megalonychidae, a group today represented only by sloths of genus Choloepus. The neocortical sulci are homologous to those found in living Tardigrada, Bradypus (Megatheriidae) and Choloepus (Megalonychidae). These share a common brain pattern, but differences on the neocortical sulci can be noted. Choloepus pattern is more complex than Bradypus one. E. fronto, although a Megalonychidae, has a brain with a Megatheriidae neocortical pattern. The Megalonychidae Ortotheriinae, structural ancestor of living Choloepodinae, is less gyrencephalic with respect to the last one. These neuromorphological traits would be consistent with the more gerealized traits that define the Ortotheriinae. During the Early Miocene the morphological differences that do display between the brains of recent Megatheriidae and Megalonychidae could not be shown. Indices of encephalizaton computed for E. fronto suggest that its brain stands close to the size expected for a moder Megalonychidae.