- Chordates evolved from invertebrates and display traits like bilateral symmetry, segmentation, and a gut tube. Chordates are distinguished by having a notochord, dorsal nerve cord, pharyngeal slits, post-anal tail, and myotomes (blocks of muscle) at some stage of their life. - Vertebrates are chordates that have evolved additional traits like a skull, vertebral column, and endoskeleton. They have undergone further diversification into groups like fish, amphibians, reptiles, birds, and mammals which have specialized for various environments.

1. Invertebrates Chordata Vertebrates

11. Subphylum Cephalochordata Urochordata

13. SubPhylum Cephalochordata Exclusively marine animals ; they are capable of swimming but usually are buried in the sand with only their anterior end being exposed

28. Garstang's Hypothesis called this process paedomorphosis, a term that describes the presence (or evolutionary retention) of juvenile or larval traits in the adult body

44. South American Lungfish : a living species of Lepidosiren . look at the four slender "fins" of this fish, which are homologous to the four legs of terrestrial vertebrates. Lung Fishes - Sarcopterygii

47. An extinct tetrapod genus, among the first vertebrates to have recognizable limbs which appeared in the Upper Devonian about 365 mya, and was anatomically intermediate between lobe-finned fishes and the first tetrapods fully capable of coming onto land.

48. An early tetrapod that lived in the Upper Devonian period, 367-362.5 mya. It was a labyrinthodont that represents an intermediate form between fish and amphibians. It possessed lungs and limbs that helped it navigate through shallow water in swamps.

52. Fire salamender - Salamandra salamandra Leaf Green Tree Frog - Litoria phyllochroa Toad - Bufo marinus