英语听力：2013-03-29 恐龙之战之极限生存 Extreme Survivors—5

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If you see a stork¹ on the Nile today eating a baby crocodile, you can imagine in your mind Quetzalcoatlus eating a baby Tyrannosaur 65 million years ago.

 

You can never know how well Tyrannosaurs could count, but I imagine mom would be a little bit perplexed² when suddenly she was down to five instead of six. And there was no sign of where it had gone. 

 

For a baby Tyrannosaurus Rex, danger lurks³ everywhere, but at least he has a fighting chance. For infant Sauroposeidon, it’s a very different story. They are born defenseless and alone.

 

If you want to have intensive parental⁴ care, you can only take care of a limited number of offspring. If you want to have lots of offspring, you have to have little or no parental care, and Sauropods took that route.

 

From birth, Sauroposeidon is in a race for survival. For every 3,000 hatchlings, only one will make it to adulthood⁵. And to become that one survivor⁶, it must fend⁷ for itself for years. For this future giant, there’s just one rule—grow or die.

 

When we look at Sauropod tracksites where we have tracks of hundreds of individuals altogether, there’s a curious thing. These big groups of Sauropods always include only the adults and the animals down to about 1/3 of full size.

 

Growing up alone means growing up in constant danger. 

 

So think about a juvenile⁸ Sauroposeidon. It’s the size of a pony⁹ or a horse. It has no sharp teeth, no plates, no spikes¹⁰, no horns, no armor. It’s not even very fast. And so what would happen to those juvenile Sauroposeidons if they are faced by a pack of Deinonychus? Well they would die.

 

And Sauroposeidon navigates¹¹ a world of hungry predators¹².

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