2/18/2013. Notochord Dorsal, hollow nerve cord Pharyngeal slits or clefts Muscular, post-anal tail. Cephalochordata. Dorsal, hollow nerve cord

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1 1 cm Dorsal, hollow nerve cord Pharyngeal slits or clefts Muscular, post-anal tail Muscle segments Muscular, post-anal tail Anus Dorsal, hollow nerve cord Pharyngeal slits or clefts Mouth Osteichthyes Dorsal, hollow nerve cord Cirri Mouth Pharyngeal slits Tail Atrium Digestive tract Atriopore Segmental muscles Anus 1

2 Tail are more closely related to other than are lancelets Muscle segments Intestine Stomach Atrium Dorsal, hollow nerve cord Excurrent Pharynx with slits Incurrent Excurrent Anus Intestine Esophagus Water flow Stomach Incurrent to mouth Excurrent Atrium Pharynx with numerous slits (a) Tunicate larva (b) Adult tunicate (c) Adult tunicate Tunic 2 or more clusters of Hox genes skull, brain, eyes, and other sensory organs neural crest Higher metabolic rate and more extensive muscular system 2 chambered heart Red blood cells with hemoglobin Kidneys to remove waste products 5 mm Pharyngeal slits Segmented muscles Dorsal edges of neural plate (a) Neural crest Skull bones and cartilage derived from neural crest cells (c) (b) Neural tube Migrating neural crest cells Small brain, eyes, ears, and tooth-like formations Hagfishes are marine; most are bottom-dwelling scavengers Slime glands 2

3 Second gene duplication involving the Dlx family of transcription factors Vertebrae enclosing a spinal cord An elaborate skull Fin rays, in the aquatic forms Basal vertebrates They are jawless vertebrates that feed by clamping their mouth onto a live fish Dental elements (within head) Dorsal fins include sharks and their relatives, ray-finned fishes, lobe-finned fishes, amphibians, reptiles (including birds), and mammals 0.5 m Pectoral fins Pelvic fins (a) Blacktip reef shark (Carcharhinus melanopterus) (b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei) 3

4 The vast majority of vertebrates belong to a clade of gnathostomes called Osteichthyes Nearly all living osteichthyans have a bony endoskeleton include the bony fish and tetrapods Aquatic osteichthyans are the vertebrates we informally call fishes Ray-Finned Fishes and Lobe-Fins Operculum swim bladder Nostril Cut edge of operculum Brain Gills Kidney Spinal cord Heart Liver Stomach Swim bladder Intestine Gonad Dorsal fin Anus Pelvic fin Adipose fin Urinary bladder Anal fin Lateral line Caudal fin Ray-Finned Fishes and Lobe-Fins sea horse (Hippocampus ramulosus) Yellowfin tuna (Thunnus albacares) Red lionfish (Pterois volitans) Fine-spotted moray eel (Gymnothorax dovii) 4

5 Four limbs, and feet with digits A neck, which allows separate movement of the head Fusion of the pelvic girdle to the backbone The absence of gills (except some aquatic species) Ears for detecting airborne sounds Fish Characters Scales Fins Gills and lungs Eyes on top of skull Flat skull Tetrapod Characters Neck Ribs Fin skeleton Flat skull Eyes on top of skull Neck Shoulder bones Fin Ribs Elbow Radius Scales Fin skeleton Humerus Ulna Wrist (a) Tadpole (b) During metamorphosis (a) Order Urodela (salamanders) (b) Order Anura (frogs) (c) Order Apoda (caecilians) (c) Mating adults are tetrapods that have a terrestrially adapted egg AMNIOTE Reptiles Synapsids Diapsids Archosaurs Lepidosaurs Dinosaurs Saurischians Parareptiles Turtles Crocodilians Pterosaurs Ornithischian dinosaurs Saurischian dinosaurs other than birds Birds Plesiosaurs Ichthyosaurs Tuataras Squamates Mammals The extraembryonic membranes are the amnion, chorion, yolk sac, and allantois Embryo Amniotic cavity with amniotic fluid Shell Amnion Extraembryonic membranes Allantois Chorion Yolk sac Albumen Yolk (nutrients) 5

6 Eggs of most reptiles and some mammals have a shell relatively impermeable skin ability to use the rib cage to ventilate the lungs tuataras, lizards, snakes, turtles, crocodilians, birds, and some extinct groups scales that create a waterproof barrier Most reptiles lay shelled eggs on land (a) Tuatara (Sphenodon punctatus) adaptations that facilitate flight The major adaptation is wings with keratin feathers Other adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth (b) Australian thorny devil lizard (Moloch horridus) (c) Wagler s pit viper (Tropidolaemus wagleri) (e) American alligator (Alligator mississippiensis) (a) Wing Finger 1 (b) Bone structure Palm Finger 2 Finger 3 (d) Eastern box turtle (Terrapene carolina carolina) Shaft Vane Forearm Wrist Shaft Barb Barbule Hook (c) Feather structure Archaeopteryx remains the oldest bird known Toothed beak Wing claw Living birds belong to the clade Neornithes Several groups of birds are flightless The ratites, order Struthioniformes Penguins, order Sphenisciformes Certain species of rails, ducks, and pigeons Airfoil wing with contour feathers Long tail with many vertebrae 6

7 Mammals have Mammary glands, which produce milk Hair A high metabolic rate, due to endothermy A larger brain than other vertebrates of equivalent size Differentiated teeth small group of egg-laying mammals consisting of echidnas and the platypus opossums, kangaroos, and koalas The embryo develops within a placenta in the mother s uterus A marsupial is born very early (a) A young brushtail possum in its development It completes its embryonic development while nursing in a maternal pouch called a marsupium Marsupial mammals Plantigale Marsupial mole Sugar glider Wombat Tasmanian devil Kangaroo Eutherian mammals Deer mouse Flying squirrel Mole Woodchuck Wolverine Patagonian cavy (b) Long-nosed bandicoot Compared with marsupials, eutherians have a more complex placenta complete their embryonic development within a uterus, joined to the mother by the placenta PRIMATE Lemurs, lorises, and bush babies Tarsiers New World monkeys Old World monkeys Gibbons Anthropoids Orangutans Gorillas Chimpanzees and bonobos Humans Time (millions of years ago) 7

8 (a) Gibbon (b) Orangutan (c) Gorilla (d) Chimpanzees (a) New World monkey: spider monkey (b) Old World monkey: macaque (e) Bonobos Humans are mammals that have a large brain and bipedal locomotion A number of characters distinguish humans from other apes Upright posture and bipedal locomotion Larger brains capable of language, symbolic thought, artistic expression, the manufacture and use of complex tools Reduced jawbones and jaw muscles Shorter digestive tract Australopiths are a paraphyletic assemblage of hominins living between 4 and 2 million years ago (a) The Laetoli footprints (b) Artist s reconstruction of A. afarensis Stone tools have been found with H. habilis, giving this species its name, which means handy man Homo ergaster shows a significant decrease in sexual dimorphism (a size difference between sexes) compared with its ancestors Homo erectus originated in Africa by 1.8 million years ago Neanderthals, Homo neanderthalensis, lived in Europe and the Near East from 350,000 to 28,000 years ago They were thick-boned with a larger brain, they buried their dead, and they made hunting tools Debate is ongoing about the extent to which genetic material was exchanged between neanderthals and Homo sapiens 8

9 : notochord; dorsal, hollow nerve cord; pharyngeal slits; post-anal tail : two sets of Hox genes, neural crest : Dix genes duplication, backbone of vertebrae : hinged jaws, four sets of Hox genes : bony skeleton : muscular fins or limbs : four limbs, neck, fused pelvic girdle : amniotic egg, rib cage ventilation 2/18/2013 Clade (lancelets) Description Basal ; marine suspension feeders that exhibit four key derived characters of Homo sapiens appeared in Africa by 195,000 years ago All living humans are descended from these African ancestors (tunicates) (hagfishes and relatives) (lampreys) (sharks, rays, skates, ratfishes) (ray-finned fishes) Marine suspension feeders; larvae display the derived traits of Jawless marine organisms; have head that includes a skull and brain, eyes, and other sensory organs Jawless vertebrates; typically feed by attaching to a live fish and ingesting its blood Aquatic gnathostomes; have cartilaginous skeleton, a derived trait formed by the reduction of an ancestral mineralized skeleton Aquatic gnathostomes; have bony skeleton and maneuverable fins supported by rays (coelacanths) (lungfishes) Ancient lineage of aquatic lobe-fins still surviving in Indian Ocean Freshwater lobe-fins with both lungs and gills; sister group of tetrapods (salamanders, frogs, caecilians) Have four limbs descended from modified fins; most have moist skin that functions in gas exchange; many live both in water (as larvae) and on land (as adults) (tuataras, lizards and snakes, turtles, crocodilians, birds) (monotremes, marsupials, eutherians) One of two groups of living amniotes; have amniotic eggs and rib cage ventilation, key adaptations for life on land Evolved from synapsid ancestors; include egg-laying monotremes (echidnas, platypus); pouched marsupials (such as kangaroos, opossums); and eutherians (placental mammals, such as rodents, primates) 9