As he searches he continues to think.
Whether it’s the stimulant of this odor or the involuntary dry retching he did earlier, his digestive system has awoken now, and his stomach is tightening with hunger cramps, despite the overall gruesomeness of the scene. The desire to eat is beginning to distract him, and testing how his immortality handles mild starvation does not seem like a fruitful endeavor at this time.
He forcibly brings his attention back to the mystery of the jawbone. He knows something of how predators behave. Small pack hunters usually bite at the legs until the prey is immobilized, then make repeated small attacks till the thing bleeds out and lies still. A large predator is likely either to intentionally kill by ripping out the throat, like a lion, or to simply pin the thing and begin eating its trunk, like an ice bear. In all cases, the soft central organs tend to be the most prized portion for their taste and nutrients. Failing to find any of his own in a pile of this magnitude does suggest either that his torso was eaten or that the enemy preferentially smashed his head.
It feels like the same Option a), Option c) forking again… For if the enemy is clever and aware of his immortality, then it might choose to target the brain to cause maximum amnesia. And if the enemy is an insatiable predatory beast that enjoys the taste of his flesh in particular, then it may well have eaten the inner organs, which it did not need to shatter bone to reach, and then moved on to the brain, which it did not fully consume, but was obliged to smash his skull to reach.
Perhaps his torso was broken open, furnishing some of the volume of blood (there sure is a lot here) but it then reconstituted itself in place, while his head was so shattered that it had to be built from scratch?
Does that mean his tattoos did not need to be restored in this cycle? And if his body were burned to ashes, upon resurrecting, would he have fresh, clear skin? Or would it be restored even more grizzled but with the tattoos intact?