Velociraptors have killer claws and are established brawlers. They have been featured in the film Jurassic World and webcomics like XKCD by Randall Munroe. According to Natural History Museum, the first fossil of a Velociraptor was found on August 11, 1923, in the Gobi Desert in Mongolia.

Since then, scientists have learned a lot about the turkey-sized predator like their habit of hunting at night that was not previously identified.

Diurnal vs. Nocturnal Dinosaurs

Soft tissues, like eyes, during the period between death preservation. But paleontologists Ryosuke Motani and Lars Schmitz identified one feature of the skull that allowed them to investigate whether dinosaurs were active at night. These are the circle of bones called sclerotic rings.

It tells scientists how big the eyes of dinosaurs were and what is its shape. Sclerotic rings surround the eye's pupil and iris and are also found in birds, lizards, and other vertebrates.

According to Smithsonian Magazine, sclerotic rings are associated with the light conditions when an animal is active, whether during the day or night.

Animals today who have wider sclerotic rings are nocturnal, while those animals active during the day have smaller apertures relative to their eye size.

But dinosaurs do not all fall into just two categories: nocturnal and diurnal groups. For instance, herbivore dinosaurs like Corythosaurus, Saurolophus, Protoceratops, Plateosaurus, and the Diplodocus were probably active during the cool parts of the day and then again around twilight.

On the other hand, small dinosaurs like Juravenators, Microraptors, and Velociraptors have evidence of sclerotic rings that are consistent with a nocturnal lifestyle.

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Dinosaurs At Night

One of the famous fossils found of a Velociraptor shows it locked in combat with Protoceratops. Natural History Museum reported that it is the most dramatic evidence of two dinosaurs fighting.

Museum dinosaur researcher Dr. David Button said that the fossil gives a snapshot of dinosaur behavior during the Mesozoic Period that is rarely seen.

Motani and Schmitz said that considering the night-hunting habits of Velociraptors and the cathedral pattern of Protoceratops, it is most likely that the deadly encounter between the two dinosaurs happened at twilight or in low-light conditions, Smithsonian Magazine reported.

They noted that the previous belief that dinosaurs were more active during the day no longer holds any truth to it. They concluded that their findings offer evidence that the Mesozoic Period night time was not as safe as had been presumed as many agile predatory dinosaurs like Velociraptors were around, making mammals at that time more fearful in the dark.

Further studies on how the activity of mammals overlaps with the dinosaurs are needed to understand how they behave during those times. Unlike dinosaurs, mammals do not have sclerotic rings, so some other techniques should be used.

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