Dinosaurs

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 dino...

Dinosaurs

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