Modern monkeys can thank their ancient forerunners for their advanced digestive systems. A new study in the journal Proceedings of the National Academy of Sciences shows that prehistoric monkeys can offer insight into the inner workings (literally) of monkeys living today.
The study, authored by James B. Rossie, Christopher C. Gilbert, and Andrew Hill, analyzes two fossil teeth from Kenya belonging to 12.5-million-year-old Old World monkeys; those belongoning to the infraorder Catarrhini. Monkeys are often classified into Old World—those that originated in Africa and Asia; and New World—monkeys from the Americas. Old World monkeys are more closely related to humans. Their morphology differs from New World monkeys in a few different ways; most notably, Old World primates have a tail that isn’t prehensile, or cannot grab onto objects.
Paleontologists have long wondered about the origin of Old World monkeys. There is a significant gap in the fossil record for land animals in Africa, so scarce evidence of Old World primates exists between 6 and 15 million years ago. Until now, that is. The fossils studied by Rossie and colleagues were the oldest Catarrhini fossils ever discovered by three million years.
Finding fossilized teeth of an ancient creature is incredibly useful to paleontologists. Many species have specific characteristic about their dentition that belongs only to that species. Rossie and his colleagues could tell from the particular shape and markings on the two teeth—one molar and one premolar—that they belonged to Old World monkeys. More specifically, these teeth were the chompers of ancient an colobine, a kind of Old World Monkey that have narrow incisors, a deep jaw, and molars with high, sharp cusps. (Read more about colobines at umich.edu)
The scientist also used the teeth to determine feeding patterns about these ancient primates. The markings on the teeth indicate that these monkeys fed mainly on seeds and unripe fruits. Their digestive systems, therefore, must have been complex and able to break down tough fiber. This adaptation probably stuck around in later monekys. Today’s monkeys utilize a strong digestive system to break down leaves and other vegetation, which makes up the majority of their diet. So even though millions of years ago monkeys were feeding on completely different food sources, their digestive systems remain similar to those of today’s primates.
Read this study in the journal Proceedings of the National Academy of Sciences.
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