Lepospondyli

Lepospondyli is an extinct group of mostly small early tetrapods known from the Carboniferous and Permian periods. Its members had distinctive spool-shaped vertebral centra formed around persistent notochords.

Tetrapoda: Tetrapods are vertebrates with four limbs or descended from four-limbed ancestors. Lepospondyls belong to the early diversity of tetrapods.
Diplocaulus: Diplocaulus is an extinct aquatic lepospondyl amphibian with a distinctive boomerang-shaped skull. Its broad, horned skull is among the most recognizable lepospondyl body forms.
Temnospondyli: Temnospondyli is a diverse extinct group of early tetrapods, ranging from small forms to large aquatic predators. It is the other major fossil group often considered in debates over modern amphibian ancestry.
Phylogenetic nomenclature: Phylogenetic nomenclature names groups according to evolutionary relationships and common ancestry. Changing tree hypotheses alter which fossils and living groups count as lepospondyls.
Vertebral centrum: A vertebral centrum is the central body of a vertebra, surrounding or replacing the notochord. Lepospondyl vertebrae are characterized by distinctive spool-shaped centra.
Microbrachis: Microbrachis is a small, aquatic lepospondyl from the Carboniferous of what is now the Czech Republic. It exemplifies the small-bodied, aquatic members of the group.
Anthracosauria: Anthracosauria is a group of extinct reptile-like tetrapods, often placed near the ancestry of amniotes. Its members provide a contrasting route to amniotes in early tetrapod family trees.
Fossil record: The fossil record is the preserved evidence of past life in geological materials. Uneven preservation leaves major gaps in the history of lepospondyl diversity.
Notochord: The notochord is a flexible, rod-shaped support structure present in chordate embryos and some adult animals. Persistent notochords shaped the vertebral anatomy used to identify many lepospondyls.
Hyloplesion: Hyloplesion is a small Carboniferous lepospondyl known from fossils in Central Europe. Its fossils help document the diversity of early lepospondyls.

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