Deoxyribonucleic acid (DNA), the universal carrier of genetic information, is present in all organisms while they are alive. When they die, their DNA begins to decay under the influence of hydrolysis and oxidation. The speed of this decay varies on a number of factors. Sometimes, the DNA will be gone within one century, and in other conditions, it will persist for as many as one million years. The average amount of time detectable DNA will persist though is somewhere in the middle; given physiological salt concentrations, neutral pH, and a temperature of 15°C, it would take around 100,000 years for all the DNA in a sample to decay to undetectable levels.If fossils of the dinosaurs were less than 6,000 years old, detectable fragments of DNA should be present in a sizable percent of dinosaur fossils, especially in the Arcticand Antarctic regions where the decay of DNA can be slowed down 10-25 fold. A claim that soft tissues in a Tyrannosaurus fossil had been recovered in 2005has since been shown to be mistakensupporting the idea that dinosaur fossils are extremely oldMore recent work appears to support Schweitzer’s claim with limited speculation on how the DNA survived.Prior to this was a report on DNA extraction from a 3.8 million-year-old ostrich egg shells
That and 32 more evidence!!