Woher kommen alle Primaten?

Today, there is great diversity among primates. However, this diversity was much richer some tens of millions of years ago. A Belgian fossil represents the oldest evidence of this rich history. Our paleontologist Thierry Smith takes us back in time. 

Reinout Verbeke

Th. Smith: "To encounter the earliest primates, we must go back at least 56 million years, to the beginning of the Lower Eocene. After the extinction of the dinosaurs 66 million years ago, mammals experienced significant growth. Within about ten million years, a group with some typical characteristics developed, which scientists would later call 'primates.' While most other mammals still have eyes on the sides of their heads, primates have eyes oriented forward. This provides them with stereoscopic vision, allowing them to see in three dimensions. Primates also have opposable thumbs and big toes, which enable them to grasp objects. In other mammals, these digits are still aligned with the other fingers and toes. Additionally, primates have nails instead of the claws found on the front and rear paws of other mammals." 

What is the oldest primate fossil? 

"The oldest primate we know today is Teilhardina, that lived about 56 million years ago. It was discovered in the 1920s in Belgium, at Dormaal. At this site in the Flemish Brabant, collaborators from our Institute found many other primitive mammals. The French paleontologist and Jesuit Pierre Teilhard de Chardin described the primate in 1927 based on a few jaws and isolated teeth. He named it Omomys belgicus, that was later renamed Teilhardina belgica. In total, about 300 fossils of this primate have been discovered, including limb parts, which give us a better idea of what Teilhardina belgica looked like: a small leaping quadruped with flexible elbows and very long fingers, ideal for climbing trees." 

Did this primate live exclusively in our regions? 

"Fossils of the genus Teilhardina have also been found in Asia and North America. The Asian fossils exhibit even more primitive characteristics. The primate may have originated in the East before migrating to Europe during a global warming event 56 million years ago, through dense subtropical forests. Later, it would have reached North America via Greenland, which at that time formed a wooded bridge between the two northern continents." 

"Teilhardina is an extremely important discovery for primatology, as it is the oldest known primate. Teilhardina is also currently the earliest descendant of the Haplorhini, the branch that includes tarsiers and monkeys, as well as the great apes and humans—'our' branch. The other primitive subdivision, the Strepsirrhini, includes lemurs and lorises. In India, our team has found the most primitive Strepsirrhini fossils, which are 54.5 million years old. By comparing these two oldest groups and identifying their common characteristics, we can imagine what their common ancestor, the earliest primate, looked like." 

 

The Belgian fossil is from the oldest primate from whom we descend 

- Thierry Smith (paleontologist) -

 

And what did this oldest primate look like? 

The current mouse lemur seems to be the closest to what he looked like: a lightweight, with large eyes, prehensile hands and feet, and the ability to make powerful jumps." 

Where did the first primates appear?

"We don’t know yet. Perhaps in Asia, as that’s where we’ve found the most primitive primates dating back to the Lower Eocene. However, too few excavations have been conducted in Africa and India to find primates from this period, so it is also possible they originated there." 

And what about humans? 

"Humans only arrived much later. By the end of the Oligocene, around 25 million years ago, the great apes separated from the other Old World monkeys. Great apes (Hominoidea) do not have tails and have a less mobile spine. They evolved into two distinct groups: the hominids and the hylobatids (gibbons). By the end of the Miocene, about 8 to 9 million years ago, hominids split into two groups: one leading to gorillas and the other to humans, chimpanzees, and bonobos. And starting around 7 million years ago, the first humans (Hominini, think of Sahelanthropus 'Toumaï', Australopithecus 'Lucy', and later Homo species) began to diverge from modern chimpanzees and bonobos. Thus, Homo sapiens is not an end point, as many still believe. Humans are a branch of the vast genealogical tree—or rather, the dense 'genealogical bush'—of primates."