▶ Your Answer :
The reading passage contends that
pterosaurs had no ability for powered-flight. On the other hand, the lecturer
brings up several points which contradict this argument.
First of all, the speaker argues that the
pterosaurs present an important trait of warm-blooded animals. Since
powered-flight requires lots of energy, so they should be warm-blooded animals
if they had the ability. Recent research supports that they have dense,
hair-like covering furs which are used to maintain their temperature in the
midst of warm-blooded animals. This casts doubts on the reading passage which
states pterosaurs must have been cold-blooded animals. The writer supposes that
since modern reptiles are cold-blooded, so the pserosaurs, their ancient
reptile, must have had same features.
Also, according to the lecturer, anatomical
features show that pterosaurs were light enough to fly with their wings. This
is supported by the fact that their bone is hollow, so their weight is
extraordinarily light compared to their size of the body frame. This refutes
the writer's idea that pterosaurs were too heavy to fly.
Final point made by the lecturer is that
their behavioral mechanism used to fly was totally different from that of
birds. Birds only used two rims on their hind legs to take off from the ground.
On the other hand, pterosaurs used four rims together to take off. It might
have made them possible to run quickly and jump high which are needed to start
flying. This counters the reading passage's assertion that small and muscles
indicate the disability of pterosaurs to fly.
To sum up, there are three reasons
suggested to contradict the reading passage. According to the lecturer, pterosaurs
were warm-blooded animals, had low weight and their behavioral mechanism was
proper for powered-flight. |