(KCEN) -- If you're holding out hope that a real world Jurassic Park will one day open, keep on dreaming.
Scientists now say it's impossible because actual dinosaur DNA is long gone.
The study comes after claims that genetic material from dinosaurs could still be used in cloning.
Science journal, "Nature," reports that DNA has a half life of 521 years.
Researchers used 158 DNA-containing leg bones from extinct birds that were between 600 and 8,000 years old.
And by comparing the specimens, scientists learned that after 521 years, half the DNA bonds would break down.
Degradation would then continue until all DNA is gone.