Reading:Animal fossils usually provide very little opportunity to study the actual animal tissues because in fossils the animals' living tissues have been largely replaced by minerals

The reading states the recent study of T. Rex's fossils that may contain tissue of the animal and provides three reasons of support. However, the professor explains the reasons to be skeptical to these findings and refutes each of the author's claims.

First, the article claims that the leg of the T. Rex posses inside several branching channels. Thus, these channels could be the hollows which support the blood vessels previously. The professor refutes this point by saying that the structure could have a different explanation. Moreover, the speaker states that bacteria could provoke the channels. Therefore, the channels were created by residue left by bacteria rather than blood vessels.

Second, the reading posits the presence of spheres which suggests the remains of blood vessels. However, the professor says that identical red spheres were seen in other animals that lack of blood cells. Furthermore, the sphere could have another origin, such as mineral with red color.

Third, the article says that the presence of collagen confirms bone tissue hypothesis because this is the tissue we expect to find associated with the bone. The professor opposes to this point by explaining that collagen does not endure such a long time. In addition, the speaker offers other logical explanation. Perhaps, collagen came from the researchers' skins who were manipulating the samples instead of coming from bone.