Wow, those are some impressive pics! As good as it gets without having the piece in hand.
The concentric age cracks visible on the end of the pommel
do look mighty like those of elephant ivory.
Try having a really good look at the pommel end in good clear daylight. Does the material have overlapping angular lines like these?:
If so, it's elephant ivory. Those are called
Schreger's Lines and only ivory of the proboscidians - elephants, mammoths, mastodons, etc. - show these. If you can't see anything like this, my vote is back on some kind of bone.
Super nice piece regardless! The figural hilt reminds me of the lion/Makara hilt of the Sri Lankan Kastane as discussed over in this very awesome thread:
http://www.vikingsword.com/vb/showthread.php?t=14998 - however, I'd be surprised if that was anything but mere coincidence.
Congratulations on the score and may you enjoy it in good health!
Best wishes, - Thor