920 综合
The reading talks about three recent discoveries by opening the T.rex's leg bone, while the professor is skeptical and refutes all these findings by providing counter evidence respectively.
First, according to the writer, hollows in the bones should be the location of blood vessels, while the lecturer contradicts this idea and argues those small branching channels can be something else. These hollows can be made by bacteria. The flexible organic substance found by scientists can also be left by those bacteria.
Additionally, the professor points those spheres can not be remains of red blood cells, which is contrary to the idea of the writer. Researchers also found this kind of spheres in more ancient animals who were not supposed to have red blood cells. In this way, the spheres with dark red color may be a kind of reddish mineral instead of remains of red blood cells.
Last but not least, although the reading material maintains the finding of collagen indicate the existence of collagen matrix, the listening material holds an opposite opinion. Those T. rex are around seventy million years old, and it is not possible for collagen to last that long. The collagen is more likely to come from a much more recent source, such as human skin from researchers who handed the bones.
To sum up, the professor is skeptical about three discoveries in the article and provides evident to prove they are invalid.
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