英语听力：完美捕食—15

Nothing this large would achieve powered flight until the 20th century, 65 million years later. And Quetzalcoatlus still may hold the record for flight duration.

Probably stay aloft for a week. Probably it could have gone for 25, 26,000 miles in a single trip.

Quetzalcoatlus is one of the most unusual and terrifying carnivores to inhabit the earth. But unlike predators such as T-Rex and Deinonychus, this flying meat eater isn’t searching for the big kill. It scours the earth from above, tracking the small, the young, the defenseless dinosaur hatchlings.

Keeping this predator airborne at altitudes as high as 10,000 feet requires a 12-meter wingspan, an accurate guidance system, and near-perfect eyesight.

What we see is an enlarged eyeball, an enlarged eye socket, and the processing centers of the brain, the optic lobes were also very much expanded.

Its 10-centimeter retina is packed with over a billion light receptors and registers as much as four times the detail of the human eye. A Quetzalcoatlus can also see a spectrum of light invisible to humans, ultraviolet.

The urine of their prey absorbs U.V. rays and then reflects them back. This creates a light trail leading straight to their quarry.

These animals had very highly developed gaze stabilization mechanisms, allowing to keep their target fixed and in focus, within the cross hairs, if you will, as they were moving through space.

The secret to gaze stabilization is hidden in the inner ear. Three interconnected tubes form what are called semicircular canals. Fluid fills each canal, and small hairs detect the tiniest movement. As a Quetzalcoatlus’ head moves during flight, signals are sent directly to the eye muscles. The eyeballs adjust, keeping an image fixed and perfectly in focus. From 300 meters in the air, a Quetzalcoatlus can pick out a T-Rex nest and even count the...