Chordata
English: Lizard faces; Vertebrates.
Members: cephalochordata, tunicata, and vertebrata; = having a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail for at least some period of their life cycles; 75000 living species
Tunicata: salps and sea squirts.
Cephalochordata: lancelets.
Hemichordata: including the acorn worms has been presented as a fourth chordate subphylum, but it now is usually treated as a separate phylum.
Echinodermata: starfish, sea urchins, sea cucumbers.
Craniata: vertebrata; vertebrata and hagfish
Vertebrata: fish, amphibians, reptiles, birds, mammals; = with vertebral column, backbone.
Class Agnatha (jawless fishes)
Class Chondrichthyes (cartilaginous fishes)
Class Osteichthyes (bony fishes)
Class Amphibia (amphibians)
Class Reptilia (reptiles)
Class Aves (birds)
Class Mammalia (mammals)
Synapsida
Chordata
Vertebrata
Synapsids: means fused arch; is theropsids, meaning beast-face; mammals and related animals; temporal fenestra, an opening low in the skull roof behind each eye, leaving a bony arch beneath each; this accounts for their name.
Pelycosaurs: primitive synapsids; mammal-like reptiles; stem mammals.
Therapsids: advanced mammals.
Tetrapods: Amphibia and Amniota; four-limbed animals with backbones or spinal columns.
Amphibia: no amnion.
Amniotes: sauropsida and synapsida; tetrapods; egg equipped with an amnion, which is an adaptation to land.
Sauropsida: reptilia and aves; sauropsids: reptiles and birds.
Synapsida: mammalia.
Eutherian mammals (such as humans), these membranes include the amniotic sac that surrounds the fetus. These embryonic membranes, and the lack of a larval stage, distinguish amniotes from tetrapod amphibians.