labyrinthodonts

Labyrinthodonts are an extinct group of tetrapods that lived from the Devonian period to the Cretaceous period. Their name, meaning "labyrinth tooth," refers to the complex, folded enamel pattern of their teeth, a characteristic shared by many, though not all, members of the group. Labyrinthodonts are generally considered to be an early, paraphyletic assemblage of amphibians, representing a transitional phase between fish and later amphibian groups.

Fossil evidence indicates that labyrinthodonts varied greatly in size and form. Some were small and lizard-like, while others were large, crocodile-like predators. Many possessed robust skeletons and appeared to be adapted for a semi-aquatic lifestyle, inhabiting freshwater environments. Their skulls were often broad and flat, and they possessed a distinct "autotomy" segment in their tails, allowing them to shed their tails if captured by predators.

The evolutionary history of labyrinthodonts is complex, and they are believed to have given rise to various amphibian lineages, including modern frogs, salamanders, and caecilians, though the precise relationships are still debated. The decline of many labyrinthodont groups coincided with environmental changes, including drier climates and the rise of more advanced reptilian forms. Their extinction marks a significant chapter in the evolution of terrestrial vertebrates.