DNA Half Life

["Richard W. Travsky" <rtravsky@uwyo.edu>]

Interesting tho not necessarily dino related - and that perhaps in the 
sense that it might imply there cain't be no Jurassic Park...

http://www.nature.com/news/2007/070806/full/070806-4.html

Microbes frozen in the oldest ice on Earth have been thawed out and 
brought back to life in the laboratory, providing new insights into how 
long living creatures can be frozen.
...
However, while some bacteria taken from 100,000-year-old ice reproduced 
quite readily, cells from the oldest ice multiplied only very slowly and 
their DNA was badly damaged. Studies of isolated DNA from the samples 
showed that it had become increasingly fragmented as time went on.

By analysing samples of ice varying from 100,000 years to eight million 
years, Bidle and colleagues calculated a 'DNA half-life'; the length of 
DNA fragments in the ice halves every 1.1 million years. This 
fragmentation is consistent with the idea that the DNA is being damaged by 
cosmic rays.
...