Predictions of decay rates (k) of mtDNA in bone at various temperatures (based on equation (3.3)). Estimates of mtDNA half-lives for three fragment lengths are indicated as well as the expected average read length (1/λ, where λ is damage fraction) after 10 000 years. The decay rates do not account for the potential initial post-mortem phase of rapid DNA decay governed by nucleases. Still, the results indicate that under the right conditions of preservation, short fragments of DNA should be retrievable from very old bone (e.g. greater than 1 Myr). However, even under the best preservation conditions at −5°C, our model predicts that no intact bonds (average length = 1 bp) will remain in the DNA ‘strand’ after 6.8 Myr. This displays the extreme improbability of being able to amplify a 174 bp DNA fragment from an 80–85 Myr old Cretaceous bone .