Is the fossil evidence modified?

[Paraleptopecten (Timothy Campbell)]

As a further note on the dating,

@Paraleptopecten

Known age igneous rocks give noticeably older dates.

That is because of contamination. They are never off by more than 10-20% of the half-life. For K-Ar dating, with a half-life of 1.25 GY, 10,000,000 years and 50 years are basically the same, given that the error bar is more like 100,000,000: 0.01 ± 0.1 and 0.00000004 ± 0.1 are identical.