Grubstake, mate, thanks for your interest and reply.
You'd be amazed.
Opal miners in general are not looking for opalised fossils which are accidental finds, or "by-catch". There are some claims eg at EMU/ Allawah and Kellie's that produce a lot of opalised fossils , among the rarest of which are bones and/or teeth. In fact, many stop mining in a claim because "all" they're finding is fossilised material 
which does not justify their time, money and effort.
Paleontologists weep at such news.
Miners who've been mining for a while will all tell you that they used to pay little attention to opalised fossils, especially any without colour, and would leave them in the tailings or throw them in the silt!!
A lot of miners still do not rate them.
Many have been destroyed by rubbing, chasing colour, in the hope that there's a stone (= $s).
Many more would have been missed entirely because they are small, or broken, or do not look like opalised fossils to an unfamiliar eye. I have a very close friend in NY to whom I often send stories and photos about my opalised fossil finds:
1) she is very patient with me, not sharing the passion 
and
2) often asks me how on Earth do I know what they are. Many just look like rocks to her.
I've been very lucky because over the years I've made good contacts with opal miners who have a really sharp eye for opalised fossils and find them fascinating, as I do 
. Nearly every trip I see something different, or find something that's been overlooked in bags/buckets of potch'n'colour that I have bought
OR
as in the case of the bone and 2 jawbone pieces above, I acquire something that's been accumulated or saved and finally shown to me.
It involves a lot of sliding-door, accidental, right-place-right-time LUCK.
