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 Thus scientists were very excited recently when it appeared that a 70 millio

Both the reading and the listening discuss the fossils of the Tyrannosaurus rex (T. rex). The author believes that T. rex fossils had remnants of real living tissues and he provides three reasons for support. The lecturer challenges the claims made by the author. He is of the opinion that none of these reasons are correct.
To begin with, the author suggests that the examination of the bone showed holes and channels that are most probably the place of the blood vessels. In addition, the article mentions that the soft and flexible organic material, which was in the channels, are remnants of real blood vessels. The lecturer challenges this specific argument by asserting that these soft substances are something else like residues of bacterial colonies. Moreover, he says that after the animal death, bacteria living inside the animal ls and leave behind traces of organic substances.
Secondly, the writer argues that the T. rex's internal bones showed ,under the microscope, spheres that contained iron. Besides, their sizes and colors in explaining that these spheres were found also in primitive animals that did not have red blood cells indicated that they are remnants of red blood cells. The lecturer, however, rebuts this claim byod cells. Thus, these spheres can not be remains of red blood cells and they are most likely reddish minerals. 
Finally, the author posits that the T. rex's legs contained collagen matrix, which is one of the living substances in bone tissue. In contrast, the lecturer cast doubt on this point by pointing out that Collagen has not been found in dead animals that are older than thousand years and it can not last longer. As a result, finding collagen in T . rex fossils that are more than a million years old,  contradicts what all researchers  know about collagen. Based on that, these collagen are most probably remains of the human skin of the researcher who handle the T. rex fossils.