Did you know that humans are not the only ones who colonized new continents by sea? The animals played the role of great sailors and were taken despite having been there for days and days on normal boats to unknown lands. A young monkey can shed new light on one of the animal world’s greatest marine epics!
About 120 million years ago, the break-up of a supercontinent called Gondwana opened the Atlantic Ocean, separating Africa from South America by several thousand kilometers. The latter remained isolated for tens of millions of years during which very special endemic animals evolved there. Then, just 3 million years ago, the formation of the Isthmus of Panama between North and South America put an end to the geographic isolation of the giant island continent, and allowed the massive arrival of new animals to the South American continent.
A sudden mysterious appearance
However, a strange mystery has paleontologists puzzled. Fossils indicate that hystricognathous rodents (today represented by a capybara, guinea pig, or naked mole rat) and human primates (which we commonly call monkeys) existed in South America about 40 million years ago. This poses a problem: these caps appear far from the South American continent, long after they were isolated. How could small wild animals have reached these isolated lands millions of years before everyone else? Many hypotheses have been put forward by the scientific community, and the generally accepted hypothesis calls for one or more crossings of the Atlantic Ocean from Africa, on occasional boats! This amazing marine scattering over clusters of plants is the origin of many colonizations of isolated lands by animals that would not normally have access to them, in particular Mammals Reptiles are unable to fly or swim long distances.
For example, many of the taxa found in Madagascar likely landed there after crossing the Mozambique Channel with a catamaran. But the distance that separates Madagascar from the African continent is much smaller than that which separates the latter from South America. Does the discovery in Brazil of a new fossil ape close to an Asian species rather than an African species call into question the hypothesis of oceanic dispersal from Africa? On the contrary, a study published in the journal Proceedings of the National Academy of Sciences Brings new items!
An exceptional discovery made in difficult circumstances
Fossil finds in densely forested areas where the climate is humid are very rare, especially because fossils are also less numerous there! The researchers from the Institute of Evolutionary Sciences in Montpellier (Isem) who just described the new fossil have been probing the Amazon forests of Peru and Brazil for fifteen years, despite the difficult terrain. The conditions there are not very favorable, the sites are difficult to access, and particularly unstable. “You never know what a site will look like from year to yearFutura Laurent Marivaux (Isem), first author of the study, explains, Sediment can disappear very quickly due to rain, we must collect as much sediment as possible and sort the material directly on the ground ».
It was through sifting through these sediments that the team uncovered an unusual fossil, a tiny upper molar of a primate. “When my fellow Brazilian senior showed me, I couldn’t believe my eyesAs Laurent Marivaux says, This conformation was familiar to me, but totally unexpected in South America ».
What does this surprising kinship mean?
And for good reason: the name of a tiny primate, about 34 million years old Ashaninkacebus Simpsonswhich weighed about 230 g and fed on insects, and possibly fruit, appears to be related to them Eosimiidae, a family of Asian monkeys… does this mean that primates made the crossing between Asia and South America? Mostly not. Genetics analyzes based on dental morphologya. simpsons who showed kinship with Eosimiidae It also reveals that another molar, discovered this time in Tunisia and dated -39.5 million years ago, would have connections to the Asian family. This breed, baptized Amriyacould indicate that some primates migrated from Asia, passing through North Africa, before ending their journey in South America after a noisy crossing!
