Final answer:
The Tarsiiformes, particularly tarsiers, are considered transitional primates between prosimians and anthropoids due to their shared characteristics with both groups.
Step-by-step explanation:
The one primate that is considered to be transitional between the prosimians and the anthropoids are the Tarsiiformes. This suborder comprises the tarsiers and represents an evolutionary bridge between the more primitive prosimians, like lemurs and lorises, and the more advanced anthropoids, such as monkeys, apes, and humans. While not directly ancestral to anthropoids, tarsiers share characteristics with both prosimians and anthropoids. For instance, they have a relatively larger brain compared to most prosimians and exhibit some anthropoid traits like being primarily diurnal. This positions them uniquely in the primate evolutionary tree as a transitional form.
Tarsiers belong to the Haplorhini suborder, which also includes simians - the New World monkeys, Old World monkeys, apes, and humans. Unlike the prosimians, or Strepsirrhini, which are mostly nocturnal and have larger olfactory centers, the Haplorhini rely more on vision and are generally diurnal. Furthermore, among the prosimians, a tarsier's dentition can be seen as an evolutionary step toward the anthropoids. They also lack the ability to produce their own vitamin C, a characteristic they share with anthropoids.