It’s called wishful thinking. If the evolutionists want to prove common descent, they have to show a pattern of that variety emerging over time, as whole kingdoms and families of creatures branch off from each other. The problem lies in the fact that they can produce no clear transitional species, they only find species fully developed, distinct, and uniform in the fossil record.
To explain this away, they say that the transitional forms must have only lived a short while in terms of geological time before adapting into the commonly recognizable species they were evolving into. If this is true, they reason, then the fossils from the transitional forms would be rare. However this contradicts the Darwinian tenet of gradualism, that changes to species accumulate at a slowly, but fairly uniform pace, over long periods of time. If that were true, we would expect to see a wealth of transitional forms in the fossil record, and very few distinct species which remain for the most part unchanged over long periods of time.
To explain one contradiction, they’ve trapped themselves into another, which often happens when you are building a web of lies.
I don’t know many Darwinists, despite how the charlatans try to confuse laymen into believing that “evolutionist” is the same as “Darwinist.” It serves as a handy strawman.
It's not easy when you have too few bones, and too many opinions.