|Dinosaurs like this Pterodactyl are thought to have|
roamed the skies periodically through day and
night, according to research
Scientists have claimed that some species of dinosaur could have been nocturnal and dominated the Earth's landscape in the dark on their quest for food.
Experts studied fossilised remains of dinosaur eyes in drawing the conclusion that some paleo-beasts could have stayed awake to forage or hunt for prey.
Fox News reported that the discovery by scientists at the University of California, challenges the conventional view that early mammals were nocturnal because dinosaurs already used daylight hours to hunt.
Among 33 species of dinosaurs living in the Mesozoic era between 250 million to 65 million years ago, scientists found a spread of lifestyles which resembles those among modern animals.
Study researcher Lars Schmitz, a postdoctoral researcher in ecology and evolution at the University of California Davis, said: 'When we look at living vertebrates today, living birds, lizards and mammals we see such a great diversity of when they're active during the day.
The majority of flying dinosaurs studied — including three pterosaurs and all of the four avian dinosaurs (the ancestors of modern birds) studied — were awake during the day.
However, five species of dinosaur fliers were found to be either nocturnal or awake periodically, according to the research.
Nocturnal animals need access to the maximum amount of light into their eyes, so they need a larger opening within the scleral ring.
Predators who live and hunt in the day, however, would have a narrower opening to minimise the amount of energy needed constricting their pupils to the bright conditions.
The new research challenges the conventional view that dinosaurs mostly hunted during the dayThey studied the size of the opening inside the scleral ring, where the pupil would be, as well as the eye socket to determine the diameter of the eye, and at the diameter of the external edge of the scleral ring to determine the length of the eye.
They then compared this information with data from living species.
Both modern and dinosaur predators would have gained an advantage by hunting at night, and all of the predator species studied were either nocturnal or periodically active.
It is thought the findings could pave the way for future research into dinosaur huntings habits.
The University of California previously unearthed fossil evidence documenting an attack during twilight hours by a night dwelling species, Velociraptor mongoliensis on the periodically awake Protoceratops.