With respect to the diversification of spider monkeys in Mesoamerica,
Ford (2006) has recently analyzed the geographic changes
that occurred in South America and the Isthmus of Panama since the
late Miocene and discussed how these changes may have affected
the migration of primates into Central America. She suggests that
as early as 8–10 Ma, the Cordillera Oriental in Colombia and Venezuela
would have been a limiting barrier for the interchange of taxabetween the Amazon and the northwestern regions of Colombia
and Ecuador. Under Ford’s (2006) reconstruction, when the connection
between South and Central America was first completed
(around 3.5 Ma), the only lowland primate taxa that could have feasibly
migrated into Central America would have been those already
living in the Cauca and Magdalena valleys in Colombia and the
Choco region. Ford (2006) suggests that subsequent to the formation
of the Panamanian Isthmus, there have been two distinct
migrations of spider monkeys from northwestern South America
into Mesoamerica.