T rex.
Reading materials: 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-million-year-old fossil of Tyrannosaurus rex (T. rex), a dinosaur, might still contain remains of the actual tissues of the animal. The discovery was made when researchers deliberately broke open the T. rex’s leg bone, thereby exposing its insides to reveal materials that seem to be remains of blood vessels, red blood cells, and collagen matrix.
First, the breaking of the fossilized leg bone revealed many small branching channels inside, which probably correspond to hollows in the bones where blood vessels were once located. The exciting finding was the presence of a soft, flexible organic substance inside the channels. This soft substance may very well represent the remains of the actual blood vessels of T. rex.
Second, microscopic examination of the various parts of the inner bone revealed the presence of spheres that could be the remains of red blood cells. Tests showed that the spheres contained iron-a material vital to the role of red blood cells in transporting oxygen to tissues. Moreover, the spheres had dark red centers (substances with iron tend to be reddish in color) and were also about the size of red blood cells.
Third, scientists performed a test on the dinosaur leg bone that showed that it contained collagen. Collagen is a fibrous protein that is a main component of living bone tissue, in which it forms a so-called collagen matrix. Collagen (or its chemical derivatives) is exactly the kind of biochemical material that one would expect to find in association with bone tissue.
The article states that T.rex tissue found recently could show us remain of blood cells and provides three reasons of support. However, the speaker explains that the theory of blood vessel is not true and refutes each of the author's claims.
First, the reading claims that remain in the leg of the animal found posses branching channel, which could be hollows in bones where blood vessel were located. The professor refutes this point by saying that the soft tissue inside the leg could be something else, but blood vessels. Moreover, he mentions that the bacteria could have caused the hollows of the channel because they left behind organic materials after colonizing tissues.
Second, the reading posits that the presence of spheres on the tissue could be remaining of blood vessels. Furthermore, the author's points out that iron was found in the tissue, which is fundamental in the transportation of the oxygen in living animals. In addition, these spheres were the same color and size than red cells are. However, the professor says that these spheres were also found in other animals with no red blood cells. According to the professor the spheres could have a different origin. Thus, they could be red minerals.
Third, the article says that collagen was found; therefore this material should belong to bone tissues because they are usually associated. The professor opposes this point by explaining that collagen does not last as long as a million years. If collagen endures so long, that will change our perception of the collagen. Moreover, the speaker provides an alternative explanation. He mentions that this tissue is likely to belong to the research's skin who handled the tissue.
Attribute Value Ideal
Score: 26 in 30
Category: Very Good Excellent
No. of Grammatical Errors: 0 2
No. of Spelling Errors: 0 2
No. of Sentences: 16 12
No. of Words: 280 250
No. of Characters: 1384 1200
No. of Different Words: 145 150
Fourth Root of Number of Words: 4.091 4.2
Average Word Length: 4.943 4.6
Word Length SD: 2.328 2.4
No. of Words greater than 5 chars: 106 80
No. of Words greater than 6 chars: 75 60
No. of Words greater than 7 chars: 40 40
No. of Words greater than 8 chars: 21 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 17.5 21.0
Sentence Length SD: 5.766 7.5
Use of Discourse Markers (%): 0.75 0.12
Sentence-Text Coherence: 0.34 0.35
Sentence-Para Coherence: 0.539 0.50
Sentence-Sentence Coherence: 0.117 0.07
Number of Paragraphs: 4 4