The scientists earlier believed that the nocturnal activity, i.e. being active at night, came with the advent of mammals but a new study has refuted this previous assumption that was concluded on the basis of the fossil record.
According to the study, there were some mammal-like reptiles (synapsids) which were capable of nocturnal activity much prior to the coming of mammals.
The findings were made by a researchers team from many countries including the United States, Germany, South Africa and Canada and was led by Kenneth Angielczyk, a curator at The Field Museum.
They were first to find the breakthrough evidence that nocturnal activity was present much before the coming of mammal.
Earlier the fossil record indicated that the night lifestyle began with mammals just for the simple reason that the coordination of neural input which is required for nocturnal activity needs a large brain.
The fossil records say the first mammals had developed approx 200 million years ago.
According to the study investigators, the oldest known fossil records of synapsids suggest that these land-dwelling ancestors of mammals lived about 315 million years ago.
The researchers kept the development of eye structures as the basis of investigation. According to them, the eye structure enabled animals to see in low light conditions during the night time.
The researchers considered the fossil record of oldest known synapsid, the sail-backed carnivore Dimetrodon, examined in the study. Dimetrodon had eye bones that are consistent with night activity, the researchers found.
The fossil records were examined for finding the differences in eye bone called scleral ossicles which indicates the size and shape of the eye of an animal.
They are moreover responsible for determining the time during which the animal can be active.
It is noteworthy, scleral ossicles are absent in living mammals and only found in lizards and birds. They are also very rare in the fossil records owing to their small size.
During the research, the Synapsids were also found having a variety in eye structure that suggests some of them being nocturnal while some others as the diurnal animals.
With the new discovery, scientists say the advent of nocturnal behavior had been pushed back in time by 100 million years.
The findings of the study were published in the journal Proceedings of the Royal Society B on Wednesday.