Complex sentence: More dangerous animals like wild boar, aurochs and rhino appear to have been avoided--understandably so, given that they are thought to have relied on using thrusting spears in close-quarter ambushes.
Split into simpler sentences: More dangerous animals like wild boar, aurochs and rhino appear to have been avoided. N hunting technique is thought to have been by using thrusting spears in close-quarter ambushes.