Which subfamily of Cercopithecoids is characterized by thin enamel and a specialized stomach for a folivore diet?

The subfamily characterized by thin enamel and a specialized stomach for a folivore diet is indeed Colobines. This group of Old World monkeys is well-adapted to consuming a diet primarily made up of leaves, which are often tough and require efficient processing for digestion.

Colobines possess a unique digestive system that includes a multi-chambered stomach, similar to that of ruminants, enabling them to break down cellulose found in leaves more effectively. This adaptation allows them to thrive in their specific ecological niche where foliage is abundant. The thin enamel of their teeth is an additional specialization, which contrasts with other primates that may have thicker enamel better suited for a diet consisting of harder foods.

In contrast, the Cercopithecines, another subfamily of Cercopithecoids, typically have thicker enamel as they have a more varied diet that may include fruits and seeds, which require different adaptations in their dentition. Haplorhines and Strepsirhines represent distinct sub-orders within primates and do not fit into the categorization of the Cercopithecoids. Understanding these dietary adaptations is crucial in studying the ecology and evolution of primate species.