Stephen F. Ferrari is a Professor of Zoology in the Biology department of the Federal University of Sergipe, São Cristovão, Brazil. While his research covers a wide variety of mammalian taxa, he has a particular focus on the primate genera Callicebus and Chiropotes, their ecology and conservation.
Marilyn A. Norconk is Professor of Anthropology at Kent State University, Kent, OH, USA. Her research focuses on behavioral ecology of South American monkeys, particularly feeding ecology and social behaviour of white-faced sakis and bearded sakis in Venezuela and Suriname.