研究发现过去狗长得极像猫

New research suggests that climate change helped dogs develop from creatures resembling cats to the way they are today. Researchers from Brown University in the USA believe that 40 million years ago, dogs were smaller and hunted like cats. They hid, stalked and ambushed² their prey³. As climate change transformed Earth's landscape, the physique and food-gathering habits of dogs changed. Thick forests that once covered the North American continent started to become less dense⁴ as the planet became cooler. The emergence⁵ of grassland⁶ meant dogs had fewer places to hide to ambush¹ their victims. To adapt, they evolved their hunting styles and slowly grew longer legs.

 

The scientists analysed how dogs have evolved by looking at the elbows and teeth of 32 different species that lived between two million to 40 million years ago. The researchers said that the dogs' elbows, in particular, were good indicators⁷ of evolutionary⁸ change. Dogs from 40 million years ago had elbows that were more similar to those of cats. Their function was to allow the front paws to swivel so they could grab and hold on to prey. Those elbows changed in dogs to allow them to become endurance runners and thus be able to pursue their prey over long distances. Teeth in dogs also altered to be more efficient. They became more hard-wearing to be able to hold on to prey.

 

 

1 ambush   

n.埋伏(地点)；伏兵；v.埋伏；伏击

参考例句：

• Our soldiers lay in ambush in the jungle for the enemy.我方战士埋伏在丛林中等待敌人。
• Four men led by a sergeant lay in ambush at the crossroads.由一名中士率领的四名士兵埋伏在十字路口。

2 ambushed   

v.埋伏( ambush的过去式和过去分词 )；埋伏着

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。 来自《简明英汉词典》
• The military vehicles were ambushed. 军车遭到伏击。 来自《简明英汉词典》

3 prey   

n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨

参考例句：

• Stronger animals prey on weaker ones.弱肉强食。
• The lion was hunting for its prey.狮子在寻找猎物。

4 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

5 emergence   

n.浮现，显现，出现，（植物）突出体

参考例句：

• The last decade saw the emergence of a dynamic economy.最近10年见证了经济增长的姿态。
• Language emerges and develops with the emergence and development of society.语言是随着社会的产生而产生，随着社会的发展而发展的。

6 grassland   

n.牧场，草地，草原

参考例句：

• There is a reach of grassland in the distance.远处是连绵一片的草原。
• The snowstorm swept the vast expanse of grassland.暴风雪袭击了辽阔的草原。

7 indicators   

（仪器上显示温度、压力、耗油量等的）指针( indicator的名词复数 )； 指示物； （车辆上的）转弯指示灯； 指示信号

参考例句：

• The economic indicators are better than expected. 经济指标比预期的好。
• It is still difficult to develop indicators for many concepts used in social science. 为社会科学领域的许多概念确立一个指标仍然很难。

8 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。