Life › The age of mammals
Primates
c. 56 million years ago (first clear fossils)· Organism or group· Human ancestors & us
Strong evidenceGood evidence; dates or details still being refined.
The mammal group of lemurs, tarsiers, monkeys, apes and humans, built for life in the trees.
See it on the Life map →What happened
There are about 500 living primate species. Their hallmarks are grasping hands and feet with nails instead of claws, forward-facing eyes that judge depth, and large brains for their size. Squirrel-like possible relatives such as Purgatorius appear just after the asteroid, about 66–65 million years ago. The first clear primates, such as the mouse-sized Teilhardina, spread across Asia, Europe and North America about 56 million years ago.
Why it matters
Life in the trees shaped the grasping hands, sharp eyes and large brains that hominins later inherited and turned toward tool use.
The evidence (fossils, genes, rocks)
Teeth, jaws and skeletons from Wyoming, China and Europe, including the tiny Archicebus from China (described 2013), plus DNA family trees of living primates.
Still debated
Molecular clocks suggest primates originated before the dinosaurs died. Whether their traits evolved for climbing, hunting insects by sight or eating fruit and flowers is debated.
Inside this (2)
Connections (4)
▸Nocturnal bottleneck may explain why color vision re-evolved in PrimatesHypothesis
The connection
Early mammals, living mostly at night, lost two of the four color-sensing cone types their reptile-like ancestors had, leaving most mammals with two-color vision. Monkeys and apes of Africa and Asia regained three-color vision when a cone gene duplicated, letting them tell red from green, perhaps useful for spotting ripe fruit or tender young leaves.
When and how
Cone loss during the Mesozoic, roughly 200–66 million years ago; the gene duplication in Old World monkeys and apes about 40–30 million years ago.
How sure are we?
Cone pigment genes in living mammals show the losses and the later duplication; the night-living cause is inferred, with little direct fossil evidence.
Debates and open questions
Most primates, including lemurs and many South American monkeys, still lack routine three-color vision. Whether fruit, leaves or something else favored its return is debated.
▸Mammals radiate after the dinosaurs produced early PrimatesWell established
The connection
Primates are one of the placental lineages that diversified after the impact. Squirrel-like plesiadapiforms such as Purgatorius, possible early primates, appear within a few hundred thousand years of the extinction, feeding on fruit and insects in recovering forests. Clear primates follow about 10 million years later.
When and how
Montana, about 66–65 million years ago (Purgatorius); first clear primates in Asia, Europe and North America about 56 million years ago.
The evidence
Teeth and ankle bones of Purgatorius, described in detail in 2015, show tree-climbing traits shared with primates.
Debates and open questions
Molecular clocks suggest the primate line split off before the impact, perhaps 80–70 million years ago, but no confirmed Cretaceous primate fossils are known.
▸Messel Pit (Germany) yielded an early fossil of PrimatesWell established
The connection
In 2009 researchers unveiled 'Ida' (Darwinius masillae), a young primate skeleton from Messel, about 95% complete, with fur outline and last meal. It was promoted as a 'missing link' to monkeys and humans, but most scientists place it among the lemur-like adapiforms, a side branch, not a direct human ancestor.
When and how
Messel Pit, Germany, about 47 million years ago; dug up by private collectors in 1983 and described by Jørn Hurum, Jens Franzen and colleagues in 2009.
The evidence
The skeleton itself, unusually complete; later analyses of its anatomy place it among adapiforms, closer to lemurs than to monkeys.
Debates and open questions
Exactly where adapiforms sit on the primate family tree, and how they relate to living lemurs and lorises, is still discussed.
▸Primates led to Monkeys & other anthropoidsWell established
The connection
Early primates split into two main lines: one leading to lemurs and lorises, the other (haplorhines) to tarsiers and anthropoids. Anthropoids, the monkey branch, became larger, active by day and bigger-brained, with fused lower jaws and eye sockets closed off at the back.
When and how
Asia and Africa, about 50–40 million years ago; Eosimias from China, about 45 million years old, and Fayum fossils in Egypt, about 37–30 million years old.
The evidence
Shared skull features in early fossils, and DNA family trees placing tarsiers as the closest living relatives of anthropoids.
Debates and open questions
The order of branching among early haplorhines is unsettled, and Asian and African fossils point to different birthplaces for anthropoids.