Mammals were mostly nocturnal creatures during the Mesozoic Era or the era of the dinosaur. Fearing the dreaded attack of these giant reptiles, most of the mammals used to sleep inside their caves during the daytime and come out at night. A new finding has been published in the journal Nature Ecology & Evolution, which indicates that it was only after the extinction of dinosaurs that mammals started roaming around in the day and sleep in the night.
The study was conducted by the researchers at the University College of London and the Tel Aviv University. Before making this crucial finding, the researchers studied multiple family trees based on the 2,415 species of mammals living on the Earth today. The researchers created two phylogenic timelines, and both of them pointed to the same conclusion: mammals started coming out in daylight after the extinction of dinosaurs.
Dinosaurs fall, mammal's rise
As per the new study, the extinction of dinosaurs, following an asteroid hit before 66 million years ago, played a crucial role in shaping the evolution of mammals. The study also indicates that this switch has even designed the evolution of our own humankind.
According to the study, the first diurnal mammals emerged at some point in history between 52 to 33 million years ago. The timing suggests that the diurnal mode of mammals were triggered after the extinction of dinosaurs.
However, mammals living on the Earth today show several traits of their nocturnal lifestyle. Most of the mammals except human beings have powerful eye function that does well in low-lights. The shape of their eyes favours low-light sensitivity. The heightened sense of smell and broader ability to hear are two crucial signs which indicate that mammals were nocturnal beings. Researchers believe that gorillas, gibbons, and tamarins were the first among mammals to begin day life.