TPO 43 integrated writing

The reading passage puts forth some theories about how agnostics may have lived before becoming extinct 450 million years ago. The professor, however, points out the weakness presenting in each of the theories.

First, the speaker disagrees with the assumption that the agnostics are free-swimming predators like their ancestors, the arthropods. She further explains all types of primitive arthropods had large and well-developed eyes for the purpose of hunting. The agnostics, on the other hand, only had tiny eyes with poor eyesight that can almost be considered blind. This implies they couldn't have been predators since no evidence of their sensory organs that were needed for hunting has been discovered.

Second, it is claimed by the professor that the chance of agnostics dwelling on the seafloor is slim. In fact, creatures of the seabed can't move fast and only stay in a specific localized area. That being said, there are many agnostics found in multiple geological locations, meaning they were able to move fast and over large distances. This makes it very unusual for agnostics to have resided in the ocean bed.

Third, in the article, the author suggests agnostics could have led their life as parasites on primitive fish or larger arthropods. The professor is doubtful that this is true. Based on the vast amount of their fossils, the population of agnostics were too large to be parasites. This is because parasite population should always stay in limit; if there are too many of them, most animals couldn't have survived. Therefore, the possibility of agnostics being parasites can be ruled out.