Hi David
You could be right. I did initially think these were Shark's Teeth. I changed my mind after looking at shark's teeth, but this could be a different type I haven't spotted.
I have noticed that the teeth on the kangaroo implements I saw in the museum were pretty sharp. It is possible it was constructed of just the incisors from these animals. That would mean killing more kangaroos, of course, but there are plenty of those in Australia, so no problem there.
If they are shark's teeth, this would change the location of this artefact from central Australia to Queensland. This is a bit surprising because of the ochre on the item which I associate with central Australia more.
Regardless, the weapon still seems to have disappeared a century or so ago.
I suspect, as much as anything, it simply became obsolete as European implements became more readily accessible. A lot of work must have gone into making this - I suspect, the process of preparing the cement (for want of a better word) was pretty laborious.
It looks primitive, this knife. But it's pretty well made. Nonetheless, it has a limited function. It can't really be used for anything other than fighting. It seems to have been an implement carried almost exclusively by young men – a kind of indigenous Australian switchblade, if you like.