1) Animal order 2) Order stereospondyli 
The Stereospondyli are a group of extinct temnospondyl amphibians. Relative to other early tetrapods (labyrinthodonts), they had simplified backbones, where the whole vertebra was made of a single intercentrum, topped by a neural arch. The whole vertebral structure was rather weak, meaning that most stereospondyls were aquatic. Indeed, the family ...
[n] - formerly a suborder of Stegocephalia
order Stereospondyli noun formerly a suborder of Stegocephalia; amphibia having vertebrae whose component elements are fused into a single piece; `most vertebrates are stereospondylous`