In Jurassic Park, scientists pull dinosaur DNA out of blood-sucking insects encased in amber that is millions of years old. University of Manchester scientists, led by David Penney, show just how implausible this intriguing idea is when they failed to extract insect DNA from 10,000 year old samples.
Penney D, Wadsworth C, Fox G, Kennedy SL, Preziosi RF, & Brown TA (2013). Absence of ancient DNA in sub-fossil insect inclusions preserved in 'anthropocene' colombian copal. PloS one, 8 (9) PMID: 24039876.