Mass extinction theory attributes the extinction of living organism to collision of extraterrestrial objects such as asteroids with the Earth. The collision results into drastic climatic change due to suspended clouds of dusts that affects radiation from the sun. Drastic and intermittent occurrence of meteors and asteroid resulted to a gradual loss of living organisms during the course of the Earth’s history.
The most credible example giving plausible explanation regarding mass extinction is the dinosaur extinction, which occurred approximately 65 million years ago. Rogers claims that, “…basic experiments have been done, and it seems clear that the iridium came from an extraterrestrial source within the solar system” (25). However, debate concerning dinosaur extinction still rages. The massive impact of extraterrestrial objects did not cause mass extinction of dinosaurs.
The extinction of dinosaur may not have occurred due to drastic impact of meteors and asteroids since the probability of extraterrestrial objects to occur in future is quite negligible. “Astronomers theorized that the Oort cloud of comets could cross the path of our solar system every 26 million years, and would possibly rain comets on our planet for a few million years” (Waldner 19). This prediction has not happened and it seems it will never happen.
Dinosaur basis of mass extinction theory do not give plausible explanation for extraterrestrial bodies since they occurred only once during the period of dinosaurs and there is no possibility of future occurrence. If there was subsequent occurrence of extraterrestrial bodies and concomitant loss of living organism, then this theory would be valid, but since the occurrence is indefinite, extraterrestrial bodies did not cause extinction of dinosaurs.
Selective extinction is another line of evidence that disapproves the dominant theory of dinosaur extinction. If the great impact of extraterrestrial bodies’ collision with Earth resulted into drastic climatic change, then under what mechanism did selective extinction occur? There is no credible explanation of the mechanisms surrounding extinction and survival of organisms.
The theory concentrates on extinction without giving plausible explanation of the survival mechanism of the other organisms. Moreover, extinction studies focus on dinosaur extinction alone and extrapolated findings, and may be, other organism did not undergo mass extinction as claimed.
Joblonski argues that, “lack of understanding of the physiology of dinosaurs makes the issue more complex; if they were endothermic, why did they not survive like birds and mammals? If they were ectothermic, why did small dinosaurs not survive like small reptiles? (205). Hence, the mechanism of survival or extinction remains insufficient in explaining the nature of mass extinction.
In the determination and dating of the occurrence of extraterrestrial bodies, iridium deposits on the rock surface gives substantial evidence. Iridium originates from the solar system and their sedimentation on the rock surfaces signifies the occurrence of the extraterrestrial bodies. However, “a new study has challenged the theory by claiming that those supposed clues are nothing more than fossilized balls of fungus, charcoal, and fecal pellets” (Rogers 34).
The evidence shows that even organic matter that occur naturally on Earth when subjected to cycles of fire can produce iridium, which is a fossil complex. Therefore, fossils records have proved that fungal sediments are ubiquitous and their presence over a long period of history under intermittent fire out brakes transformed them into cretaceous fossils. Therefore, based on the evidence gathered in this research paper, the extinction of dinosaurs did not result from a massive impact event.
Works Cited
Joblonski, David. “Mass Extinctions and Macroevolution.” Paleobiology 31.2 (2005): 192–210. Print.
Rogers, Phila. “Berkeley Scientists Report First Evidence that Dinosaur Extinction Caused by Meteorite Impact.” Science Archive Journal 3.2 (1979): 23-39. Print.
Waldner, David. “Inferences and Explanations at the K/T Boundary…and Beyond.” Theory and Evidence 6.4 (2003): 1- 38. Print.