托福TPO31综合写作 Reading Part:
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.
托福TPO31综合写作 Listening Part:
The evidence that the lines in the Sinosauropteryx fossil represent feathers is very strong. The arguments of the critics are unconvincing.
First, it is unlikely that the lines are a result of the decomposition of the dinosaur ’s skin, because we don’t see any such decomposition in the fossils of other animals buried at the same site. In fact, the fossils of many other animals buried at the site show evidence that their functional skin structures have been beautifully preserved in volcanic ash. The well-preserved condition of the other fossils makes it likely that the Sinosauropteryx’s lines are also well-preserved functional structures, possibly feathers, and that they are not fibers caused by decomposition.
Second, the idea that the lines represent frills… well, there is an important chemical difference between feathers and frills. Feathers contain a great deal of a protein called Beta-keratin. Frills, on the other hand, do not contain beta-keratin. Our chemical analyses suggest that the Sinosauropteryx structures did contain beta-keratin. So that indicates that the structures were feathers, not frills.
Third, feathers can be used for other functions than flight and thermoregulation. Think of a bird, like peacock, for example. The peacock has long, colorful feathers in its tail. And it displays its tail in order to attract a mate. That’s a distinct function of feathers called the display function. Recently, we have been able to do analyses on the Sinosauropteryx structures that show us that the structures were colorful. They were orange and white. The fact that they were colorful strongly supports the idea that they were feathers that this dinosaur use for display.
Summarize the point made in the lecture, being sure to explain how the cast doubt on specific points made in the reading passage.
The reading passage refutes the idea that the lines in the Sinosauropteryx fossil indicated a feathered dinosaur by demonstrating several counterarguments. The lecturer, however, is strongly convinced that lines could represent feathers through addressing the questions advanced by the reading.
To start with, according to the reading, those lines may derive from decomposition of a died dinosaur’ skin instead of being part of a living one. The lecturer does not believe this point for the reason that other animals’ fossils that are buried at the same site have not shown such kind of decomposition; instead, their functional skin structures have been perfectly preserved in the volcanic ash. Therefore, these lines are likely to be well-preserved feathers instead of fibers.
Moving on, the reading proposes that the lines may be the frills rather than remains of feathers. The listening argues this is not true. She further explains that there is an apparent chemical difference between feathers and frills. Feathers contain protein called beta-keratin while frills do not. And the chemical analysis suggested that Sinosauropteryx’s structures contain protein beta-keratin.
Last but not least importantly, the reading puts emphasis on such a fact that lines around the backbone and the tail of the Sinosauropteryx cannot play the role of helping it fly or regulating its body temperature but common feathers have these functions. The lecturer, by contrasts mentions other functions of the feathers by using peacock as an example. The peacock has colorful feathers in its tail to attract the mate. Recent analysis has found that Sinosauropteryx’s structures are also colorful, which can also be used for display.