Dinosaurs

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 ³greenhouse effect². 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 ³greenhouse effect². Rising temperatures
could have killed off or reduced the activity of plankton, disrupting food
chains and also messing up the plankton¹s 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.