PALAEOROBOTICS UNCOVERS DEVASTATING MAMMALIAN TAIL STRIKE DYNAMICS

Extant animals occupy only a slim fraction of the evolutionary design space, leaving many high-performance morphologies unexplored without living analogues for dynamic testing. While extinct lineages lack extant model systems for comparative biomechanics, their movement dynamics can be emulated through robophysical modeling. Here, we investigate the extreme weaponization of glyptodont tails - culminating in Doedicurus - utilizing a life-sized, high-fidelity palaeorobotic strike rig. Guided by comparative analysis of caudal armour across 32 glyptodont species spanning approximately 19 million years, we derived a defence index and selected the most offensive morphology for dynamic validation. We then built a life-sized robophysical model informed by fossil caudal geometry and inertia. Collision momentum of the physical model matched simulated fossil-tail collisions closely (98-105%), and strikes onto an instrumented target reached 81.1 kN at 6.4 m/s with an impulse of 427 N s. Peak force scaled near-linearly with strike velocity, implying approximately 183 kN at a projected top speed of 15 m/s - a kinetic regime comparable to that experienced during automotive crashes. Beyond supporting a major antipredator role for extreme tail weaponization in Doedicurus, these results establish the mechanical boundary conditions for caudal weaponization and suggest that antipredator defense was the primary selective driver for these deep-time armaments. This approach establishes palaeorobotics as an experimental framework for turning functional hypotheses about extinct organisms in motion into measurable biomechanical predictions. By establishing the extreme force regimes that natural weapons can generate, this work provides a quantitative baseline for high-energy collision dynamics, and could inspire next-generation impact-resilient robotic systems and bioinspired kinetic structures.