Do biologists keep extensive libraries of genetic material from extinct or critically endangered species?

Question

If so, how much genetic material of various species do they have, and dating back how far?

Answer 1

considering that DNA is in every cell of an organism, if you had a fossil you could potentially extract genetic information from it.

it might be more complicated than this, i'm not sure.

Answer 2

Biologists generally do not keep extensive records.  A lot of work being done with genetic materical involves genome projects for various animals.  Mcmaster University in Canada is currently doing a study of the extinct Mammoth, mapping its genome and comparing it to the modern day elephants.  so far they have found that they are 98.5% identical.   Many other examples are available.  usually a biologist will take mitchondrial DNA because there are much more copies available and nuclear DNA tends to break down readily when an animal dies.  Other interesting studies include comparing human genomes with neadrathals.