Thaindian News

Washington, April 15 (IANS) Spielberg’s movie Jurassic Park had got one thing right — velociraptors hunted by night while big plant-eating dinosaurs browsed around the clock.

That overturns the conventional wisdom that dinosaurs were active by day while early mammals scurried around at night, said study co-author Ryosuke Motani, geologist at the University of California-Davis.

It’s also providing an insight into how ecology influences the evolution of animal shape and form over tens of millions of years, according to Motani and collaborator Lars Schmitz, postdoctoral researcher at California-Davis, reports the journal Science Express.

Motani and Schmitz worked out the dinosaurs’ daily habits by studying their eyes.

Dinosaurs, lizards and birds all have a bony ring called the “scleral ring” in their eyes, although this is lacking in mammals and crocodiles.

Schmitz and Motani measured the inner and outer dimensions of this ring, plus the size of the eye socket, in 33 fossils of dinosaurs, ancestral birds and pterosaurs — and in 164 living species, according to a California statement.

Day-active, or diurnal animals have a small opening in the middle of the ring while the opening is much larger in nocturnal animals.

Cathemeral animals — active in both day and night — tend to be in between. But the size of these features is also affected by ancestry.

For example, two closely related animals might have similar eye shape even if one is active by day and the other by night: the shape of the eye is constrained by ancestry, and that could bias the results.

By looking at a 164 living species, they could confirm that the eye measurements were accurate in predicting whether animals were active by day, by night or around the clock.