Chapter 34 Subphylum Vertebrata Vertebrates Chordates with a backbone Chordate features as well as: Vertebral column Series of cartilaginous or bony elements Cranium Endoskeleton or cartilage or bone Hox genes (lots of them) Neural crest Cyclostomes Jawless Fishes Class Myxini Hagfishes lack jaws, eyes, fins vertebrae skeleton comprised of notochord and cartilaginous skull covered in slime Class Cephalospidomorphi Lampreys Has notochord, and cartilaginous vertebral column lacks jaws and appendages (fins) Oldest fossil records 510 mybp Class Chondrichthyes Cartilaginous fishes Sharks, skates, rays Cartilaginous skeleton and notochord as adults jawed fishes paired appendages (fins) < 900 species Class Osteichthyes Bony fishes Most diverse vertebrate group with  < 26,000 species Bony skeleton (most do have this) Jawed paired appendages (fins) Tertapod: Gnathastomes Four limbs with jawed mouth Transition to land involved adaptions for locomotion, reproduction, desiccation (drying out) prevention, and gas exchange Sturdy lobe-finned fishes became animals with four limbs Vertebral column strengthened, ship and shoulder bones braced against backbone relatively simple changes in gene expression, especially Hox genes Class Amphibia >4000 species Amphibios greek - "living double life" split their life between aquatic and terrestrial stages Successfully invaded land but reproduce in water Lunges are and adaption to semi-terrestrial lifestyle Three chambered heart Fishes only have a two chambered heart External Fertilization Larval stages are aquatic Undergo metamorphosis Not completely separated from water Order Anura Frogs and toads Nearly 90% of amphibians Carnivorous adults Herbivorous tadpoles Order Apoda Caecilians Nearly blind tropical burrowers Secondarily legless Order Urodela Salamanders Often have colorful skin patterns Most have four limbs Amniotes Tetrapods with a desiccation resistant egg Critical innovation Development of a shelled egg Amniotic egg Broke the tie to water Three internal membranes Shell is permeable to Oxygen and CO2 Birds Hard and Calcareous Reptiles Soft and Leathery Most Mammals Embryo embeds in uterine wall Only three species lay eggs These eggs are soft and leathery Other Key Innovations of the Amniotes Desiccation resistant skin contains keratin Thoracic breathing Negative pressure sucks air in  Water conserving Kidneys Concentrate waste prior to elimination Internal fertilization Class Reptilia >8000 living species turtles, crocodilians, lizards, snakes Can live away from water thicker skin and scales larger brain larger limbs with muscles enhanced kidneys Amniotic egg "indoor pond" Vertebrate Reproductive Modes Oviparous Egg laying outside of the body Ovoviviparous live baring wuth retention of eggs No maternal connection Viviparous live bearing with egg retained Maternal connection Class Aves Birds Evolved form small dinosaurs Fossils 150mybp Adaptions for flight Feathers Modified front limbs Lightweight skeleton Organ reduction Lungs and air sacs more gas exchange Oviparous all leg layers Bill beak Encloses mouth and nasal cavity Adapted for environment Endothermic "Internal temperature" Body temperature is primarily controlled by trapped metabolic heat. Birds and mammals Ectothermic "External temperature" Body temperature is primarily related to external temperature Metabolic heat is generated but difficult to capture/maintain the heat Fishes, amphibious, reptiles Class Mammalia Milk producing Amniotes Evolved from amniote ancestors (reptiles) earlier than birds >6000 species Appeared ~ 225mybp Evolved from small mammal-like reptiles After dinosaur extinction, mammals flourished Range of sizes, body forms, and complexity unmatched Fish-like mammals Marine mammals Bird-like mammals Bats Reptile-like mammals Three egg layers Distinguishing Characteristics Mammary Glands Secrete milk All have hair In varying amounts Only vertebrate with multiple dentitions Heterodont Different types of teeth  incisors, canines, molars, premolars Thecodont Teeth with long roots embedded in sockets of jawbone Diphyodont Milk teeth that are mostly replaced by "adult" teeth later in life Pinna Flap of cartilage and lose connective tissue to channel and funnel sound The "outer ear" Three middle ear ossicles (bones) Enlarged Skull Brain enlarged in large skull Larger Cerebrum Single lower Jawbone (Dentary) Anucleate red blood cells Order Primates Primarily tree dwelling species grasping hands with  opposable thumbs Large brain Some digits with flat nails Not claws Binocular vision Complex social behavior and well-developed parental care  Enhanced sense of touch Taxonomy of Humans Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia Order Primates Suborder Anthropoidea Superfamily Hominoidae Family Hominidae Subfamily Homininae Tribe Hominini Genus Homo Species Homo s apiens