Analyses of four fossilized molars newly excavated along the left bank of the Yuruá River in the Peruvian Amazon suggest another primate lineage distinct from the Platyrrhini - until now considered to be the only primate group ever to inhabit the New World - also occupied the New World for a brief period of time. The teeth strongly resemble those of Parapithecidae, a now-extinct family of higher-order primates that resided in Northern Africa around the Eocene (56 to 33.9 million years ago) and Oligocene period (33.9 million to 23 million years ago). Like ancestors of platyrrhine primates, these African-originated parapithecids potentially rafted across the Atlantic - a narrower, yet turbulent ocean at the time - around 35 to 32 million years ago, the researchers postulate. Their results offer another intriguing detail about the origins of New World mammals and may help inform how the ancestors shaped one of the most biodiverse regions on Earth. Erik Seiffert and colleagues analyzed primate teeth discovered at a 100-meter-long sedimentary deposit along Yuruá River and found these teeth were radically different - lumpier and more bulbous, among other features - than those of platyrrhines. Statistical probability analysis placed the species, which the authors named Ucayalipithecus perdita, deep within African primate groups Parapithecoidea and Parapithecidae. Ucayalipithecus' ancestors possibly rafted to the New World across the Atlantic Ocean around the time when sea levels had dropped, in an independent rafting event from the African platyrrhines, the analyses showed. Both parapithecids and Platyrrhini must have been remarkably adaptable to harsh conditions to have survived the crossing, the authors note. Upon arrival, the primates must also have had to immediately adjust their foraging behavior to the unfamiliar land and compete for food and territory, as they both appeared to have persisted around the same time - for at least 11.5 million years. Thus, these early primates were likely highly resilient and behaviorally versatile, the authors say. In a related Perspective, Marc Godinot further explores this concept and poses questions for future exploration.