Some Biblical Creationists still claim that fossil hominid skulls are either human skulls or ape skulls, but not any kind of transition in between.  Let's take a close look at their supposition, and see if it holds up.
 

Let's think about this...
 

This is what a chimpanzee skull looks like:
            and here is what a gorilla skull looks like:
The average brain size of a chimpanzee is 390 cc.  A modern human brain size is about 1400 cc.

The gorilla skull is just too different from a human skull, so we'll leave him out of our investigation.  But there is obviously no way you could confuse a human skull with a chimpanzee, is there?  For instance, if you found a chimp skull in the dirt, is there any way you could mistake it for a human skull?  Or vice versa?
 

I doubt that you could confuse the next two examples either.  The Homo Erectus (Upright Man) skull, even with its heavy brow-ridge and lack of forehead, is still very human-looking.  But does the Homo Erectus skull look identical to the modern Homo Sapiens skull?  The brain capacity of the Homo Erectus is only about 1000 cc, smaller than that of modern man, yet twice as large as the chimpanzee.  Hmm.

 
 

The next two are also very different.  The Homo Habilis (Handy Man) skull has a relatively large brain compared to the chimp (around 700 cc), very different cheeks, larger nasal cavity and small canine teeth.  The Homo Habilis skull does not resemble any modern ape.  But its brain is only HALF the size of a modern human. So, if evolution didn't happen, who were these individuals?

 

The next one starts to resemble the chimp.  They both have elongated faces and brow ridges.  But the Africanus skull has a brain capacity larger than the chimp.  Notice that the Africanus does not have sharp canine teeth, as the chimp does, and look at the difference in the cheekbones and nasal cavity.  But is the Africanus a human skull?  No.  It is not designated as a "Homo" Africanus.  It is one of our pre-human ancestors, and through them, our relationship to our cousins, the chimpanzees, grows clear.

 

Much the same can be said of the next two.  If you found these two together, you could not classify them as the same species. The Afarensis has a brain of about 415 cc, slightly larger than the chimp. They are obviously both primates, and closely related. But the biggest difference, the difference that absolutley excludes Afarensis, or Lucy (as she is most commonly known) from being a version of chimpanzee, is that she walked upright on two legs (fully bipedal) with a modern-looking knee. The chimp has no such ability, and can only sustain partial bipedal locomotion for a few seconds at a time, due to a knee that cannot straighten out. Chimpanzees are not bipedal- they are quadrupeds. Lucy's kind walked the earth 3 to 4 million years ago.

 


There is another important thing to consider. None of these skulls: 

are found where these skulls are found: 

And so on. I wont bother putting up all the skulls again just to illustrate the point that these hominids skulls are found exactly in the order in which they are presented on this page. You don't see modern human skulls in any strata much older than about 100,000 years. You do find these other hominid fossils, and in the order that is shown here, which is exactly what you would expect if one evolved from another. That is one of the predictions of Evolutionary theory. You don't find the fossils randomized, or mixed up, as you would expect to find them if they all lived at the same time. You figure it out!


Here is another look at some of these hominid skulls. Can you call any of them monkeys? The small skull is not a child- it has fully adult teeth. Are they all modern people? Note the size of the brain cavity, brow ridge, and overall shape. The answer is obvious to anyone who does not have a priori bias against the idea.

 
 
You figure it out...