Early Chordates, Craniate and vertebrate origins

1. Part 1 Where does it start? Early Chordates, Craniate and vertebrate origins

2. Phylum Chordata

3. Animal Kingdom Vertebrates over here

4. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Phylum Chordata

5. Pikaia – a very early (fossil) chordate

6. Phylum Echinodermata Phylum Chordata - Origins Phylum Hemichordata

7. Carpoids Fossil echinoderms …..a link between non-chordates and chordates?

8. Deuterostomia Ambulacraria Hemichordata Chaetognatha Echinodermata Xenoturbellida Chordata Enteropneusta Xenoturbella Pterobranchia Loss of gill slits Pentaradiality Postanal tail Buccal diverticulum Endoskeleton of stereom ossicles Hooded circlet of spines around mouth Mesocoelomic ducts Notochord Endostyle or thyroid gland Coelom tripartite Axial complex Unique larval morphology Diffuse nervous system Unusual ciliary structure Mouth not derived from blastopore Enterocoely Gill slits in pharynx Radial determinate cleavage

9. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle 5 traits define all chordates

10. Protochordata Agnatha Urochordata (tunicates) Petromyzontida (lampreys) Myxini (hagfishes) Cephalochordata (lancelets) 5 traits define all chordates Suckerlike oral disc, long larval stage, 7 pairs of gills Slime glands, accessory hearts *notochord *dorsal hollow nerve cord *pharyngeal slits *postanal tail *endostyle Neural crest

11. Chordate Traits Endostyle

12. Adaptive significance Gill arches Vertebral Column Complex central Nervous system

13. Pikaia– a very early (fossil) chordate

14. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Phylum Chordata

15. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle “Protochordates”

16. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Craniates

17. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Vertebrates

18. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle “Fishes”

19. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle “Fishes”: 6 distinct lineages

20. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Tetrapods Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle

21. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Amphibians

22. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Amniotes Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle

23. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Mammals (Synapsida)

24. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin n epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Diapsida (“reptiles” + birds)

25. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle

26. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia Protochordata Agnatha Osteichthyes (bony fishes) Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Testudines (turtles) Lepidosauria (lizards, snakes) Aves (birds) Sarcopterygii (lungfishes, coelacanths) Amphibia Crocodilia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Suckerlike oral disc, long larval stage, 7 pairs of gills Egg with extraembryonic membranes Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle

27. “Protochordates” Not craniates – but the same phylum

28. Subphylum Cephalochordata lancetes, amphioxus

29. notochord nerve cord perforated pharynx endostyle post-anal tail

31. Subphylum Craniata

32. Subphylum Craniata

33. Chordata (animals with notochord at some stage in life cycle) Craniata (euchordates with a cranium) = Vertebrata Vertebrata Gnathostomata (Craniata with jaws) Teleostomi (bony fishes + tetrapods) Protochordata Agnatha Osteichthyes (bony fishes) Craniata Actinopterygii (ray-finned fishes) Urochordata (tunicates) Petromyzontida (lampreys) Mammalia (mammals) Sarcopterygii (lungfishes, coelacanths) Amphibia Myxini (hagfishes) Cephalochordata (lancelets) Hair, mammary glands Chondrichthyes (sharks, rays, chimaeras) Suckerlike oral disc, long larval stage, 7 pairs of gills Heterocercal caudal fin, placoid scales, cartilaginous skeleton Paired limbs used for terrestrial locomotion Slime glands, accessory hearts Unique supportive elements in skeleton or girdles of appendages Lung or swimbladder derived from gut, bony endoskeleton Jaws, 3 pairs semicircular canals, paired appendages, gill filaments lateral to gill support 2 pairs semicircular canals, vertebrae Distinct head and tripartite brain, paired specialized sense organs, 1 pair semicircular canals, glomerular kidney, ectodermal placodes Neural crest Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle

34. Vertebrata Craniata

35. Craniate innovations Cranium

36. Craniate innovations Tripartite brain Forebrain Midbrain Hindbrain

37. Craniate innovations Complex Cranial Sense organs Olfaction Vision Hearing (otic)

38. Craniate innovations Inner ear with at least one semicircular canal

39. Craniate innovations ? Unique embryonic tissues neural crest cells ectodermal placodes

40. Acraniate Chordate Craniate

41. Very early craniates (probably) †Myllokunmingia † Haikouichthys †others

42. Very early craniates (probably) †Myllokunmingia † Haikouichthys †others

43. Relationships under debate †Myllokunmingia † Haikouichthys

44. Most primitive (living) craniate Hagfishes

45. Vertebrata Craniata

46. Vertebrata Vertebrates

47. Vertebrate innovations Vertebrae

48. Vertebrate innovations Inner ear with at least two semicircular canals

49. Vertebrate innovations All sorts of new physiology

50. Most primitive living vertebrate Lampreys