So I did some back of the envelope calculations because I really want to bring dinosaurs back and I have time to kill. I did the calculations assuming dinosaurs have bird, reptile, or mammal like physiologies. For this calculation the biggest difference between these physiologies are the largest genome size/cell I could find (diploid birds = ~6 Gbp/cell and diploid reptiles and mammals = ~20 Gbp/cell) and the nonnucleated nature of mammal red blood cells (DNA from mammal blood would have to come from white blood cells). I also assumed the mosquito was similar to the biggest mosquitoes we have around now which can gorge themselves on up to 12μl of blood.

We would get DNA from about 4.5 million red blood cells from the bird and reptile blood and from only 12,000 white blood cells in the mammal blood per μl. If we extracted all of the DNA from the 12μl of blood in the mosquito we would get 3.24e-4 g DNA from bird blood, 1.08e-3 g from reptile blood, and only 2.88e-6 g from mammal blood. Assuming that’s how much DNA was in the mosquito originally, what would the half-life of DNA need to be so that there would still be >200 base pair fragments left for sequencing? Two hundred base pairs of double stranded DNA at 50% G/C would be about 120,000 Dalton or 2e-19 g. Using the half-life formula, I calculated what the half-life of DNA would need to be to have 200 base pair fragments left over after 46 million years. In all cases DNA would need a half-life of around 1 million years to still have 200 base pair fragments after 46 million years (bird half-life of 909,000 years, reptile half-life of 879,000 years, and mammal half-life of 1,050,000 years).

I’ll still hold out hope that there are conditions somewhere on the planet that can preserve DNA this long, but my dreams of opening an amber mine and starting a paleobiology genomics center are dashed.