(CN) — Four fossilized ancient primate molars excavated from the Yuruá River in the Peruvian Amazon have provided scientists new information about the mysterious lineage of early primates in the New World, according to a study released Thursday.
Up until now scientists have only known about one primate group, the Platyrrhini, meaning ‘flat nosed’ to distinguish them from the Old World monkeys that had narrow noses.
They are affectionately known as the New World monkeys to reflect the land they inhabited. This group includes about 100 different species of primates including the brown capuchins, Bolivian squirrel monkeys, pygmy marmosets, golden lion tamarins, Chamek spider monkeys and block howler monkeys.
This new evidence, however, suggests that there was at least one more group occupying the region for a short period of time.
The newly excavated primate teeth strongly resemble those of a group called the Parapithecidae, a family of higher-order primates that resided in what is now Northern Africa around the Eocene period about 56 to 33.9 million years ago, and the Oligocene period about 33.9 million to 23 million years ago. They are said to be the sister taxonomic group to Old World monkeys and the most primitive of the primates.
Like the ancestors of the platyrrhine primates, these African-originated parapithecids may have rafted across the Atlantic, which would have been a much narrower and turbulent ocean at the time. The authors estimate this would have occurred around 35 to 32 million years ago, landing in the Oligocene era.
Although primates sailing across the Atlantic sounds bizarre, rafting is a phenomenon that has been discussed and debated in the paleontological field for decades – though it is no easy feat.
The concept of oceanic dispersal describes an event in which organisms will raft across bodies of water on a large floating mass of land or vegetation, and has been seen with rodents, snakes, birds, and more.
It’s probable that if the primates in question had rafted on a floating land mass with vertical trees that could have acted as sails, it would have taken them roughly two weeks to cross the Atlantic – a testament to their resilience against the elements as they would have been without food, water or shelter from the sun for the duration of the travel.
The results of this study, published Thursday in the journal Science, propose another fascinating detail about the origins of New World mammals and potentially provide an explanation for how the ancestors shaped one of the most biodiverse regions on Earth.
Lead author Erik Seiffert of the USC Keck School of Medicine, whose work mainly focuses on fossil mammals from the Eocene and Oligocene eras of Africa, and his colleagues spearheaded the analysis of these remains.
After studying these primate teeth, discovered in a 328-foot-long sedimentary deposit along Yuruá River in the Amazon rainforest, they found that they were vastly different from those of platyrrhine primates. Among some other differentiating features, the molars were much lumpier and more bulbous in texture and size than the comparing counterparts.
The authors named this new species Ucayalipithecus perdita, and based on the statistical probability analysis, these creatures would have existed deep within African primate groups Parapithecoidea and Parapithecidae.
Ancestors of the Ucayalipithecus likely would have rafted to the New World across the Atlantic Ocean near the time when sea levels had dropped and the authors note it would have been an independent rafting event from that of the African platyrrhines based on the analyses.
Both the parapithecids and the Platyrrhini would have needed to be exceptionally adaptable to be able to survive the harsh conditions of crossing the Atlantic, the authors point out.
Furthermore, upon arriving to the New World, these ancient primates would have also had to immediately and completely adjust their foraging behavior to feed themselves in the unfamiliar land, and not to mention compete with the local fauna for territory.
They would have additionally been in competition with one another, as evidence shows they both appeared and thrived in the region around the same time for at least 11.5 million years.
The authors emphasize that these early primates were remarkably resilient and versatile in behavior, as they survived through some of the most unforgiving conditions.