All science is an art. The idea that science is clear-cut and there are always definitive answers is mostly propaganda meant for mass consumption. In the real world, it’s not so simple.
Also, there are no “transitions.” There is a continuum, where specimens taken at various intervals might be different, but there is no point at which one can say “it was this; now it’s that.”
Art is subjective, no? And to be a continuum there can’t be gaps or else it isn’t continuous, no?
From Wiki:
Continuum - anything that goes through a gradual transition from one condition, to a different condition, without any abrupt changes
I am not aware that the fossil record is that complete and clear.