You have that backwards numbnuts.<quoted text>The DNA survived n T.rex bones that had been PRESUMED to be 67 million years old.
The 67 million year old T-Rex bone is presumed to have DNA in it.
The amount of evidence for the bone being millions of years old makes its millions of years age undeniable. The amount of evidence for DNA being present is much much much weaker. If you want to insist that some part is presumed you would go for the one with the WEAKER evidence, not the claim that has the STRONGER evidence.