Whether the weapon killed the mastodon is a question that cannot be definitively answered from the available evidence.

The injury to the rib was real and documented.

The penetration of the rib wall — significant bone damage — would have been painful and potentially debilitating.

But whether this injury, alone, would have been fatal to an animal the size of a mastodon is uncertain.

Mastodons, like modern elephants, had substantial reserves of physiological resilience.

It is possible that the weapon — the one whose tip broke off inside the rib — was one of several delivered in the same attack, and that the mastodon died from the cumulative effects of multiple injuries.

It is possible that the rib injury was fatal on its own.