英语听力:2013-05-22 完美捕食 Perfect Predators —9(在线收听

 And Sauroposeidon like most plant eaters are smelly. Unlike a meat eater, they produce huge amounts of waste, feces that form a trail marking everywhere they’ve been. For Deinonychus, that odor is a dead giveaway. And this carnivore’s eyes can clearly see prey from a great distance.

 
A scan of Deinonychus skull reveals a brain with an oversized optic nerve, the nerve which transmits visual information from the eyes. 
 
The optic nerve is very large, too. And the eye socket is very large. 
 
 
 
It’s like having a broadband connection between the eyes and the brain. This high-speed link means Deinonychus can react quickly to even subtle changes in its environment. 
 
If we look at the Deinonychus eye, it’s probably gonna be about an inch across, a lot of space in there for photoreceptors. It could see well at night. It would have just a superb sense of sight.
 
Unlike a mammal, Deinonychus has no blood vessels in its retina, what we see as red-eye in flash photographs. This simple design change creates space for many more rods and cones more than twice the number of photoreceptors found in the human retina. And the additional rods means Deinonychus can see in the dark as if looking through night-vision googles. 
 
This animal had very sensitive vision being able to actually discriminate objects with great clarity and acute vision. 
 
These are the characteristics of an alpha or apex hunter. Yet highly advanced senses aren’t their only weapon. Deinonychus is agile and can reach speeds of 60 kilometers per hour. And, it has almost-perfect balance. 
 
It would have been swift. It would have been swifter than a human being certainly, but its real ability would have been agility. It’s a sort of animal that could probably turn on a dime.
  原文地址:http://www.tingroom.com/lesson/yytltsfx/2013/246041.html