No doubt that much of human pre-history lies beneath the sea on what was once dry land. Until finds are made, it will remain conjecture but the future will provide the means of finding those deposits. Together with improved DNA analysis, we will soon look back on our level of knowledge today and shake our heads. I remember my early days of geologic studies when the hard evidence for the movement of continental plates emerged and a hare-brained theory became well accepted.
I looked at Kow Swamp some more and found this particularly good analysis of the arguments, homo erectus vs h.s., including 16 points of specific comparison.
http://www.canovan.com/HumanOrigin/kow/kowswamp.htm
As I read this I found myself asked repeatedly, “well, have they done the DNA analysis of the bones and the various groups of aborigines in widely separated areas of Australia?” Unfortunately, a lot of the bones have been reburied as a sop to the native population which is not necessarily even related to these folk. I guess they had their own Kennewick Man problems.
I remember learning valence chemistry in high school, but when I went to college they were teaching atomic shells chemistry. Not a word about valences.