All Yesterdays: Curl Up and Hopefully Not Die

My final submission to the All Your Yesterdays contest involves an Edmontonia longiceps. Many modern animals protect themselves with armour similar to ankylosaurs - for example armadillos, pangolins and girdled lizards. A defence common to all three of these, amongst others, is to roll themselve into a tight ball with their tails by their heads and their limbs tucked in. This minimizes the soft areas open to predators. Now, such a defence would be impractical with a multi-tonne adult Edmontonia, but a hatchling or baby could easily utilise this defence mechanism against threats - here represented by a snooping Atrociraptor, though that beetle doesn't look too friendly either. This behaviour would eventually become impossible and the animal would turn to the more general lower-your-belly-to-the-ground technique it is thought to have utilised, but for the first few years of its life, any predator to come close would see what originally seemed like a tasty morsel transform into a tough, keratinous, rock-solid ball of tooth-breaking and complaints.