Hyperossification

Hyperossification is when there is much more bone material on a bone than usual. Hyperossification is found in frogs. Many frogs have smooth skulls, but some frogs have skulls that only look smooth from the outside. Under their skins, their skulls have spikes, ridges, flanges, or unusual neck joints.
Even frogs that did not come from the same ancestor evolved big, spiky skulls if they ate the same other animals: usually animals almost as big as they were, like birds and mice. Scientists say this is because big, strong skulls let the frogs have big mouths and strong jaws that are good for catching big prey.
Other frogs have spikes inside their skin to protect from predators. When a bigger animal bumps into the frog's head, the spikes break open sacs full of venom under the frog's skin, and this protects the frog from being eaten.
Name.
The word hyperossification means "a lot of bonemaking."