I don’t think it’s a Dinocephalia. It looks a bit flat for that (Dinocephalia are quite cylindrical in cross section and are pretty much confined to Allocasuarina and Casuarina species). It’s possibly a Synechocera however the photos are not good enough to tell. I’m not sure what plant it’s on as that might also help with ID. If it’s still around then some better photos will help.
Is the size '12mm to 25mm' correct? It's not Dinocephalia. Nor is it Synechocera, which is more elongate (and has never been collected in this region). I agree with MarkH that it looks like Anilara, and it also looks like Neocuris, but no species reach 12mm. Ignoring the size, I'd say the colour and shape match Neocuris.