A thrown spear without an atlatl could be delivered from somewhat greater distance but with less force than an atlatl-propelled dart.

An atlatl — a spear-throwing board that uses leverage to increase the velocity and effective range of a thrown spear — could deliver a dart from considerably greater distance with higher impact energy.

The force required to penetrate a mastodon’s rib cortex from outside — to drive a bone tip through dense, mineralized bone — was substantial.

Mastodon cortical bone is not soft material.

The penetration documented at Manis required a significant amount of kinetic energy delivered in a small area: concentrated force at the point of a weapon tip.