Mammals gave up night life only after dinosaur doom:

Mammals gave up night life only after dinosaur doom:

Context:

• Research says that earliest mammals were night creatures.
• They emerged from darkness only after the demise of the daytime dinosaurs.

What is the explanation behind the research?

• The earliest mammal ancestor emerged between 220 million and 160 million years ago, evolving from a reptilian forebear.
• And according to studies, it was probably nocturnal.
• Dinosaurs, on the other hand, were likely day-dwellers seeking out sunlight to warm their bodies like reptiles today.
• The mammals hid out in darkness for so long, possibly to avoid competition with dinosaurs for food or territory, or being eaten by them.
• The data revealed that mammals remained nocturnal throughout the Mesozoic period, which ended about 66 million years ago when a massive calamity, possibly an asteroid strike, wiped out the dinosaurs and about three-quarters of life on Earth.
• Mammals, then mainly small, scurrying animals, survived, and flourished.
• Primate ancestors were thus among the first mammals to become strictly diurnal, possibly as long as 52 million years ago.

Mammals in the present day context:

• Mammals, apart from primates, lack a part of the eye known as the fovea, which many fish, reptiles and birds have and is replete with photoreceptor “cone” cells for seeing colour in high light.
• Instead, they tend to have more “rod” cells, which can pick up scant light in dim conditions, but provide relatively low resolution.
• Modern-day mammals, which are active mostly by day including types of squirrel, tree-shrews, some antelope and many carnivores  also still tend to have a keen sense of smell and acute hearing, attributes required for living in the dark.