A new species of monkey that lived 22 million years ago in Africa "helps fill a 6-million-year void" in primate evolution, according to a new study.
Identified by its fossilized teeth, the new species, known as Alophia metios, was found in the badlands of northwest Kenya. The teeth may give clues on how their diets helped shape the course of evolution.
"For a group as highly successful as the monkeys of Africa and Asia, it would seem that scientists would have already figured out their evolutionary history," said the study's corresponding author, John Kappelman, in a statement.
Kappelman continued: "Although the isolated tooth from Tanzania is important for documenting the earliest occurrence of monkeys, the next six million years of the group's existence are one big blank. This new monkey importantly reveals what happened during the group's later evolution."
The teeth lack molar crests known as "lophs," which helped scientists name the monkey Alophia, which means "without lophs."
The teeth are so old, they were initially mistaken for a pig, Wake Forest University professor Ellen Miller said in the statement. "But because of other dental features, we are able to convince them that yes, it is in fact a monkey."
Previously discovered teeth were dated between 19 and 25 million years, from Uganda and Tanzania, respectively. Monkeys first originated when Africa and Arabia were together on an island continent, some 24 million years ago.
In analyzing the fossilized teeth, researchers believe it ate hard fruits, seeds and nuts, in a part of the world that was full of lush vegetation and streams. "These ancient monkeys were living the good life," said Benson Kyongo, a collections manager at the National Museums of Kenya.
The fossilized teeth may also help shed light on whether monkeys faced competition from other animals on the continent, such as pigs, lions or rhinos, for food, which may have caused them to evolve.
"The way to test between these hypotheses is to collect more fossils," Kappelman said. "Establishing when, exactly, the Eurasian fauna entered Afro-Arabia remains one of the most important questions in paleontology, and West Turkana is one of the only places we know of to find that answer."
The study was published in Proceedings of the National Academy of Sciences on Monday.