Dinosaurs Essay, Research Paper

Dinosaurs: How they became extinct Something happened 65 million years ago, at

the end of the Cretaceous period, something so devastating that it altered the

course of life on earth. It seems like it happened so sudden, as geologic time

goes, that almost all the dinosaurs living on earth disappeared. So how did

these dominant creatures just die off? Was it a slow extinction, or did it

happen all of the sudden? These questions bring rise to many different beliefs

on how the dinosaur disappeared over 65 million years ago. Extinction itself is

easily defined: When the birth rate fails to keep up with the death rate, it is

called extinction. But, the definition does not answer the question about the

nature or causes of extinction. Paleontologists generally divide extinctions

into two types, for that of different causes arose. The first is called

background extinctions, isolated extinctions of species due to a variety of

causes. Included is out competition, depletion of resources in a habitat,

changes in climate, the development or destruction of a mountain range, river

channel migration, the eruption of a volcano, the drying of a lake, or the

destruction of a forest, grassland, or wetland habitat. The second type of

extinction is called mass extinctions. There are four main components involved:

Large numbers of species go extinct; many types of species go extinct; the

effects must be global; and the effects must occur in a geologically short

period of time.1 The dinosaur could not have lived for ever. No creatures, no

plants, no tiny bacteria are forever, not even Homo sapiens. Extinction is the

fate of all species. One theory on how the dinosaurs became extinct is that of

carbon dioxide, and the ?greenhouse effect?. Volcanoes produced the proposed

conditions. A massive volcanic eruption could have saturated the atmosphere with

carbon dioxide so that it caused a sharp rise in temperatures worldwide. The

excessive carbon dioxide would have permitted solar energy to enter the

atmosphere but would have blocked the radiation of most surface heat back out

into space, therefore causing the ?greenhouse effect?. Rising temperatures

could have killed off or reduced the activity of plankton, disrupting food

chains and also messing up the plankton?s normal role in converting carbon

dioxide to oxygen through photosynthesis. From there it would not have been long

for all the dinosaurs to have been suffering, and then to become extinct.