User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-7584137-20140825113054/@comment-5043481-20140826223229

I think it is quite possible that the glacial one was around first (or something much more like the glacial one). The lack of ice uroktor could be explained by different breeding habits. Glacial might find it better to produce a small clutch of eggs (or live young) in an underground cave where they can be fed until much bigger. For the lava species this might not be viable as lava flows could engulf the babies, either killing outright them or encasing them in solid rock. So it produces hundreds of offspring to counter the ones eaten as it can't nest safely.