Pierre-Paul Grassé.
First of all, you do realize that he was not a creationist, right?
He was a neo-Lamarckian.
Basically, his point was that mutations did not equal evolution. That population could remain evolutionary stagnant for a long time despite mutations.
That part is quite correct, that is because a mutation is not always beneficial for the whole population.
Furthermore, the benefits of a mutation is environment, ie selection, dependent. So a beneficial mutations in the lab is not necessarily a beneficial one in the population in the wild.
Mutations are the fuel of evolution, but natural selection is the engine driving it forward.
A big point of Grassé was that of living fossils, organisms that were seemingly untouched by evolution despite living in a different environment.
We now know that he was wrong.
First of all, a relatively stable environment is required for 'living fossils', if the environment change too much, either the species evolve or go extinct.
More importantly, his work was conducted before the achievements of molecular biology. So, if the fossils he looked at remain mostly unchanged, he concluded that they did not evolve. But now we can look in more detail and we can see that populations do evolve all the time. These evolutionary changes might not always leave fossilized traces, but now that we can look more closely at their genome, we can see that evolution do, indeed, occur.
