Wednesday, November 30, 2005

When was the Cretaceous Period?


The Cretaceous period was long long ago. It extended from 140 million years ago until 65 million years ago. It was the last period of the mesozoic era, often called the 'Age of the Dinosaurs'. The end of the cretaceous was marked by a mass extinction event where many species of marine and land animals, including dinosaurs became extinct as well as the majority of land plants.

There are 5 great extinction events in the geological record and the dramatic ending of the cretaceous is the last of them. There are many theories and much controversy, which I will keep away from (at least for the moment). I will leave the last word to Tim Flannery in his book "We are the Weather Makers : The story of Global Warming"

The last time the earth was afflicted (*) was 65 million years ago, when every living thing weighing more than 35 kilograms, and the vast number of smaller species, was destroyed

(* he is talking about mass extinctions)

Aren't we humans all larger than 35 kg, I know I am!

2 comments:

Will Baird said...

WRT to Tim Flannery's comment, it isn't quite true. There was an extinction at the end of the Eocene related to the methane 'burps' and very warm warming: http://upload.wikimedia.org/wikipedia/en/9/91/Extinction_Intensity.png

I'm sure that you knew that though.

imageo said...

Thanks for your comments will. Yes I like the Methane "burp" theory (there may have been several, I might discuss those in a later post) and yes the Eocene is more recent.

But somehow the eocene event hasn't made the Big 5 extinctions list in the text books(yet!)

By the way, I don't entirley agree with tim, cause sharks and crocodiles are bloddy big they made it through. However tim's book is still worth a read, (generally) well researched and put together in a readable fashion.