Can anyone suggest the origin of this jawbone. It was found in far north Queensland in Australia. The section with teeth measures 6.4cm x 1.9cm. The large teeth are approximately 1cm x 0.3, the middle teeth are approximately 0.7 x 0.3 cm and the largest of the little round teeth are approximately 0.2cm diameter.
Well, I'm quite confident that is a fish. It reminds of some pycnodonts (compare image F http://www.thegcr.org.uk/GIA%5C16%5CFigures%5CJPEGsLoRes%5CGCRv16c13f006.jpg which is part of a splenial from Coelodus mantelli) from the Mesozoic (which oddly enough fits with this geological map of Queensland: http://www.flickr.com/photos/stonemasonry/3257640742/). Also see http://www.oceansofkansas.com/FossilFish/Pycnodont/VP-7280.jpg (note that two rows of teeth are missing!).
But, being far from an expert, I stop at fish (well Bony fish, Osteichtyes and, if fossil, possibly Pycnodontiformes).
Perhaps this can be of interest... Pycnodont fishes: morphologic variation, ecomorphologic plasticity, and a new interpretation of their evolutionary history: http://www.kmnh.jp/publication/ronbun_pdf/A3-169-E-Poyato-Ariza.pdf and why not contact DR Bellwood of the James Cook University (see http://www.labome.org/expert/australia/james/bellwood/d-r-bellwood-316753.html) who is thanked in the acknowledgements section (he sure knows far more than I know of this and might actually be interested).
Try the Queensland museum
They might be able to help you!
One final further development thanks to Mark McGrouther at the Australian Museum. He kindly made the effort to identify this jawbone to species level for me. I originates from the bumphead parrotfish - Bolbometopon muricatum