Order Stereospondyli includes a diverse group of extinct amphibians that lived during the Mesozoic Era. This order is characterized by a unique vertebral structure, with double-headed ribs fused to the centra, resulting in a stiff and powerful backbone. Some common synonyms used for Order Stereospondyli are gomphodonts, rhachitomous amphibia, and temnospondyls. These synonyms reflect the different aspects of the anatomy and lifestyle of these ancient creatures. Gomphodonts refer to the complex teeth of some Stereospondyls, while rhachitomous amphibia emphasizes the unique vertebral structure. Temnospondyls, on the other hand, is a more widely recognized term used to describe the broader group of amphibians to which Stereospondyls belong.