The Jurassic Park method of extracting dinosaur DNA from mosquitoes preserved in amber is scientifically plausible.
While mosquitoes and other insects do preserve in amber and can retain blood meals, the biological premise fails at DNA degradation. DNA degrades systematically; estimates suggest complete degradation within 6.8 million years under ideal conditions (permafrost). After 66 million years, no intact dinosaur DNA sequences would remain extractable. Additionally, degraded DNA cannot be 'filled in' with frog genes as the films suggest, a scientific impossibility. Although the premise makes for compelling storytelling, it violated known molecular biology principles even in 1993. Recent ancient DNA work confirms DNA's limited preservation window.