Articles for ielts the dangers of being over-confident

particularly adapted for high-speed, head-to-head impacts.
They found this structure was far more effective at absorbing impacts than 
that of other modern animals adapted to heavy head impacts, such as musk oxen. 
The researchers believe that the evolution of this unusual skeletal structure was 
driven by headbutting courtship competitions. This means it was likely to also be 
true for the evolution of the unique neck and head anatomy seen in modern giraffes, 
they say. “Both living giraffes and Discokeryx Xie Zhi belong to the Giraffoidea, a 
superfamily. Although their skull and neck morphologies differ greatly, both are 
associated with male courtship struggles and both have evolved in an extreme 
direction,” said the study’s first author Dr. Wang Shiqi.
The researchers believe that during the emergence of the genus Giraffa seven 
million years ago, the direct ancestors of modern giraffes developed a way of 
fighting by swinging their necks and heads into one another. Along with sexual 
selection, this behaviour led to the extreme elongation seen in modern giraffes over 

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the following two million years. This would also have made them particularly well-
suited for the niche of feeding on high foliage as a consequence, the researchers say. 
New words
Foliage(n)- the leaves of a tree or plant; leaves and branches together 
Courtship(n)- the special way animals behave in order to attract a mate 
To whip(v)- to hit a person or an animal hard with a whip, as a punishment or to 
make them go faster or work harder 
Ossicones(n)- are columnar or conical skin-covered bone structures on the heads of 
giraffes 
Blow(n)- a hard hit with the hand, a weapon, etc. 
To deem(v)- to have a particular opinion about somebody/something 
Hierarchy(n)- a system, especially in a society or an organization, in which people 
are organized into different levels of importance from highest to lowest