Lepospondyl

Lepospondyl is an extinct order of tetrapods that lived during the Carboniferous and Permian periods. These amphibians were generally small and slender, with many species resembling modern salamanders. Their most distinctive feature, and the basis for their name, is the structure of their vertebrae. In lepospondyls, each vertebra was formed from a single, spool-shaped ossification, known as a pleurocentrum, which fused with the intercentrum, a cartilaginous or bony structure that was also present in other early tetrapods. This contrasts with the more complex vertebral structure found in their contemporaries, the embolomeres, and in later tetrapods.

Lepospondyls were diverse, with over 200 described species. They occupied a variety of ecological niches, from aquatic forms with external gills to more terrestrial species. Fossil evidence suggests they inhabited freshwater environments, swamps, and perhaps even damp terrestrial habitats. Their diet likely consisted of small invertebrates. Despite their relatively primitive vertebral anatomy, lepospondyls were a successful group for a significant portion of the Paleozoic Era. Their exact evolutionary relationships to other tetrapod groups have been a subject of debate among paleontologists, with various studies proposing different placements within the amphibian lineage.