Evolution 101 :)

Anotheca spinosa, a tree frog from Central America, likely uses the bony spikes on its skull as a defense against predators. Credit: Edward Stanley/Florida Museum

Frogs, cannibals to the max, also have another amazing trait, skull variability based on the type of prey they hunt and the kind of defense they use against predators who eat them.

Hemiphractus scutatus, a horned frog from South America, can prey on other vertebrates, thanks to its wide skull with a large gape. This species also has fanglike structures on its lower jaw. Credit: Edward Stanley/Florida Museum

Many frogs look like a water balloon with legs, but don’t be fooled. Beneath slick skin, some species sport spines, spikes, and other skeletal secrets.

While most frogs share a simple skull shape with a smooth surface, others have evolved fancier features, such as faux fangs, elaborate crests, helmet-like fortification and venom-delivering spikes. A new study is the first to take a close look at the evolution and function of these armored frog skulls.

Florida Museum of Natural History researchers used 3D data to study skull shape in 158 species representing all living frog families. Radically shaped skulls were often covered in intricate patterns of grooves, ridges and pits formed by extra layers of bone. The research team found that this trait, known as hyperossification, has evolved more than 25 times in frogs. Species with the same feeding habits or defenses tended to develop similarly shaped and patterned skulls, even if they were separated by millions of years of evolution.

Most frogs share a simple skull shape with a smooth surface. But some species evolved elaborately armored skulls, adapted for capturing large prey or defense. Credit: Daniel Paluh

Evolution 101 without question. :)