Mesozoic mammals came alive at night

… or the long-held assumptions finally confirmed.

Skull of Repenomamus Giganticus - Source: Laikayiu, Wikipedia (CC BY-SA 3.0)

It has been many decades since paleontologists first assumed that mammals living in the age of dinosaurs were the so-called “bottoms”. In other words, they were most likely little-frightened animals that hid during the day and became active only during the night when the dinosaurs went to bed. But this assumption has a few holes – for example, we know that not all Mesozoic mammals were small and that some were even eating the younglings of small dinosaurs.

A recently published study from the science team from the Tel Aviv University shows that our image is pretty much correct – our Mesozoic ancestors were night animals and that was the case until the extinction event 66 million years ago. Only after the extinction of the dinosaur rulers, the first fully daytime groups of mammals appear. So the viewpoint that says that if it wasn’t for the extinction of dinosaurs we would have not likely been here along with most other mammal species.