Their anatomy falls between the mainly aquatic Devonian labyrinthodonts and the first reptiles. All of the teeth possessed maze-like enamel folding similar to other "labyrinthodonts". Their skulls were relatively deep and narrow compared to other labyrinthodonts. The most diverse group of labyrinthodonts was the Temnospondyli. The vertebrae showed the typical multi-element construction seen in labyrinthodonts. The group is traditionally considered to be a suborder or order of labyrinthodonts. The American paleontologist Ermine Cowles Case called it Labyrinthodonta "vera" or "true labyrinthodonts". The Mesozoic labyrinthodonts were primarily aquatic with increasingly cartilaginous skeleton. This would have made most labyrinthodonts slow and clumsy on land. Colosteids lacked otic notches at the back of the head, unlike temnospondyls and other "labyrinthodonts". Amniotes branched from labyrinthodonts in the subsequent Carboniferous period. Like their sarcopterygian ancestors, the labyrinthodonts were carnivorous. The labyrinthodonts flourished for more than 200 million years. The first tetrapods, or land-dwelling vertebrates, were piscivorous amphibians known as labyrinthodonts. The reptiles appeared from labyrinthodonts in the subsequent Carboniferous period.