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Official 31 Task 1
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A fossil skeleton of a dinosaur called Sinosauropteryx, preserved in volcanic ash, was discovered in Liaoning, China, in 1996. Interestingly, the fossil included a pattern of fine lines surrounding the skeletal bones. Some paleontologists interpret the lines as evidence that Sinosauropteryx had feathers. However, critics have opposed the idea that Sinosauropteryx was a feathered dinosaur, citing several reasons. 

First, the critics points out that the fine lines may not even represent functional structures of a living dinosaur, but rather structures that were formed after the animal’s death. After the animal died and was buried in volcanic ash, its skin may have decomposed into fibers. The skin fibers then became preserved as lines in the fossil; the lines were misinterpreted as evidence of feathers. 

Second, even if the fine lines are remains of real structures of a Sinosauropteryx, scientists cannot tell with certainty what part of the dinosaur’s anatomy the structures were. Many dinosaurs had frills, ornamental fan-shaped structures growing out of some parts of their bodies. Some of the critics argue that the lines surrounding the skeleton are much more likely to be fossilized remains of frills than remains of feathers. 

A third objection is based on the fact that the usual functions of feathers are to help animals fly or regulate their internal temperature. However, the structures represented by the lines in the Sinosauropteryx fossil were mostly located along the backbone and the tail of the animal. This would have made the structures quite useless for flight and of very limited use in thermoregulation. This suggests that the lines do not represent feathers.

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Now listen to part of a lecture on the topic you just read about.
Quackers are certainly a very strange phenomenon.
Experts still debate what the source of the sounds was.
No one can be sure exactly what caused them, but these experts cite certain problems with all of the theories that you just read about.
Here are a few of the arguments that they make.
First, the idea that the sounds were caused by orca whales seems plausible at first, but is ultimately highly unlikely.
It’s true there were orca populations in the general areas that the Russian submarines were patrolling, but orca whales mostly live near the surface of the water.
The submarines typically remained deep in the ocean and should not have been able to hear the whale sounds from near the surface.
Also, the orca whales would have been detected by the Russian sonar if they were nearby.
Giant squid may be a better candidate, but one critical fact speaks against the squid theory as well: Russian submarines first detected quacker sounds in the 1960s, and reports of them continued for about two decades, but the sounds disappeared entirely by the 1980s.
However, as far as we know, squid have always lived in the ocean where the submarines were patrolling, and continue to live there today.
If these were squid sounds, there would be no reason to suddenly start hearing them in one decade and then suddenly stop hearing them twenty years later.
Third, the idea that the quackers were caused by a secret submarine from another country does not hold up.
The sources of the sounds appeared to move around and change direction very quickly.
Submarines cannot move or change direction that quickly.
Also, all submarines make some engine noise, but no such noise accompanied the quackers.
Even today, we don’t have technology to build submarines that are that fast and have engines that are that silent.
Question

Summarize the points made in the lecture, being sure to explain how they respond to the specific argument made in the reading passage.