Cathemerality-Behavior in which an organism exhibits activity during the day or night in which food is obtained or socializing with other animals occur. This is seen in many mammals, mostly primates, but has been studied greatly in lemurs of Madagascar with five extinct species of lemurs of the genus eulemur exhibit cornea sizes inbetween those of nocturnal and diurnal strepsirrhines. Results show that cathemerality in eulemur is an ancient adaptation of lemur found in their last common ancestor.
Kirk, E. C. (2006). Eye morphology in cathemeral lemurids and other mammals. Folia Primatologica, 77(1-2), 27-49.
Eulemur coronatus (Crowned Lemur)
