Contrary to popular thought, some dinosaurs were not asleep when the sun. According to new research, many animals stayed awake at night to hunt prey.
This discovery, based on fossil evidence eyes the remains of dinosaurs , contradicts the conventional information that claimed that early mammals were nocturnal, or active at night because they were dinosaurs during the day.
But to respond if there are chances that dinosaurs were nocturnal hunters is a very difficult task because, as we know, only remain some fossilized bones.
The group of scientists set about this task began by analyzing the size of the ocular cavities, and the dimensions of the scleral ring, a region of the bones surrounding the iris of the eye in birds, lizards, and dinosaurs (humans and other mammals not possess).
Scleral ring The study could shed some light on the subject, because the nocturnal animals need to capture the maximum amount of light possible, and this requires greater openness within the scleral ring.
By contrast, diurnal animals have small eye openings, allowing them to save energy and not have to get his pupils constantly in daylight, and it allows them to see clearer and sharper images at long range during the day.
Andrewsi Protoceratops, active herbivore night and day
In the fossils, the researchers examined the proportions of certain features of the eye to determine the habits of the species analyzed. They then compared the information obtained from the data of species today.
Around about 33 species of dinosaurs that lived during the Mesozoic period (between 250 and 65 million years ago) were similar in their characteristics to the lifestyle of modern animals.
It was found that 8 species of flying dinosaurs, three species of pterosaurs would be awake during the day, while five species were nocturnal or active during periods of the night. Two of these five species rather their behavior asemejarían of nocturnal seabirds today.
Fossil belonging to a Velociraptor, nocturnal activity
Most herbivorous dinosaurs stayed awake periodically. The enormous size of these animals mean that spent much time feeding and grazing during the day and night. In addition, these animals were prone to heat stroke, so trying to avoid activity during the hottest times of the day, exchanging his move in the evening hours, according to the study.
Finally, predators, both dinosaurs like these, get always an advantage when hunting at night, and all analyzed predatory dinosaurs were nocturnal or active at night regularly.
In conclusion, the result of the research indicates that dinosaurs and early mammals did not separate the day from the night in the course of their activities, as they do most mammals.