After doing some preliminary research on Egyptian sphinxes, I've noticed that there are many oddities with the heads. I found this old topic, where the original poster was encouraged to resubmit his question.

I'm fairly new to Egyptology, but here are the few oddities that immediately jumped out at me.

The Sphinx of Hetepheres II clearly has something wrong with the positioning and quality of the head as compared to the rest of the body. The head protrudes directly from the chest, and is there is a sharp jagged edge between where the neck meets the human head/face.

The Great Sphinx of Giza also has a head that's very poorly proportioned as well. The head appears to belong to a creature of at most half the size of the body. Moreover, the head, which has must have been exposed to the elements more so than the buried body, retains a much higher level of detail. The lines are still visible in the headdress, whereas the body is virtually entirely degraded, even though it was buried.

I'm surprised that most of the propositions that sphinxes originally had different heads are disregarded as fringe theories, can anybody elaborate?