Single-cell. Colonial. True multicellular. Bilateran. Chordate. Vertebrate (fish). Amphibian. Reptile. Primitive early mammal. Primate. Monkey. Ape. Various intermediate hominids. Man.
I oversimplify, of course. It's really a smooth transition all the way.
Why is it necessary for every step in a sequence to be known? Do you need to know all the primes that come before 1213 to know it is a prime? What does the question you asked have to do with the poster I was responding to having a poor grasp of evolution?
Ah... I've been asking similar questions of teachers and professors my entire life.
My expertise is not in the scientific field, but I can't help but observe the "fact" that the fossils of creatures which have been placed at the very beginning of the evolutionary chain can be found by the thousands, as can creatures at the end of the evolutionary chain. Yet "Evolutionists" cannot produce even one single "missing link" fossil of any species that have evolved according to the accepted theory of evolution. Tiny bits and pieces of a few apelike skulls is not sufficient evidence to secure Evolution as "fact", otherwise the word "theory" would no longer be applied by the scientific community when referring to Evolution.
I am not endorsing ID, but "common sense" tells me that some kind of fossil linking the evolution of at least one species to it's next level of development would surely have been discovered by now... "if" the theory of evolution was indeed plausible.