The movieJurassic ParkSteven Spielberg was right about one thing:velociraptors hunted at nightwhile the large herbivores also looked for food during the day, as confirmed by an American study just published by the magazineScience. This conclusion calls into question the popular belief that Mesozoic dinosaurs were active only during the day, explains Ryosuke Motani, a geologist at the University of California Davis (USA) and a co-author of the work. “It was a surprise, but it makes sense,” he admits.
In the study, Motani and his colleagues reveal that dinosaurs, lizards and birds all have a ring of bone called a “scleral ring” in their eyes, which mammals and crocodiles lack. By studying its dimensions in 33 fossils of dinosaurs, pterosaurs and ancestral birds, as well as 164 living species, the researchers have found thatdiurnal animals have a small opening in the middle of the scleral ring, while in nocturnal animals this hole tends to be much larger. In cathedral beings – active by day and night – the size of the orifice is intermediate. Thus, this anatomical feature allowspredict whether an animal is active during the day, at night, or at any time.
Thus scientists have concluded thatlarge herbivorous dinosaursWhatProtoceratops andrewsithey fed both day and night, like the current elephants, while thecarnivores such as Velociraptor were nocturnal. It has not been possible to establish when they hunted large carnivores such astyrannosaurus rexbecause its fossil remains do not preserve the scleral ring in good condition.
