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Vertebrates. The Origin of Tetrapods. The first vertebrates on land were amphibians in the Devonian May have arose from the rhipidistian (features) or a lungfish (DNA). Origin of Tetrapods. Origin of Tetrapods. Classification. Phylum: Chordata Subphylum: Vertebrata
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The Origin of Tetrapods • The first vertebrates on land were amphibians in the Devonian • May have arose from the rhipidistian (features) or a lungfish (DNA)
Classification • Phylum: Chordata • Subphylum: Vertebrata • Superclass: Gnathostomata • Class: Amphibia • Order: Urodela (Salamanders) • Order: Anurans (Frogs and Toads) • Order: Apodans (Caecilians)
Class: Amphibia • Two lives • refers to metamorphosis of many frogs • Skin smooth and moist (cutaneous respiration) • Three chambered heart with a double circulation system • Mesolecithal eggs with jelly-like membrane
Order: Urodela • 400 species • Salamanders • Retain their tail as adults • Limbs are at right angles to the body • Carnivorous
Order: Anurans • 3500 species • Frogs and Toads • Lose their tail as adults • Hind limbs are adapted for jumping • Tongue connected to front of mouth • Secrete mucus
Order: Apodans • 150 species • Caecilians • Legless and blind
Evolution of the Amniotic Egg • Allows animals to complete their entire life cycle on land • Has shell that retains water (or is lost when kept inside mammals) • Specialized extraembryonic membranes (not part of the animal)
Evolution of the Amniotic Egg • Amnion - Protects from dehydration and mechanical shock • Yolk Sac - Nutrient storage • Albumin - Nutrient storage • Allantois - stores waste, gas exchange • Chorion - gas exchange
Tough, dry skin Amniotic egg Crushing or gripping jaws Copulatory organs More efficient circulatory system with a higher blood pressure More developed lungs (thoracic breathing) Better water conservation Better body support and limbs Better nervous system How Reptiles differ from Amphibians
Classification • Phylum: Chordata • Subphylum: Vertebrata • Superclass: Gnathostomata • Class: Reptilia (not real) • Class: Testudines (Turtles and Tortoises) • Class: Spenodontia (Tuataras) • Class: Squamata (Lizards and Snakes) • Class: Crocodilia (Crocodiles and Alligators)
Reptile Radiation • Synapsids (therapsids) - led to mammals • Sauropsids • Anapsids (turtles) • Diapsids (all others)
Class: Testudines (Chelonia) • Evolved on land and returned to water (lay eggs on land) • Protective Shell • Carapace • Plastron
Class: Sphenodontia • Tuataras • Two living species (New Zealand) • Not a True Lizard (no external ears) • Very Primitive (similar to mesozoic reptiles • Well developed eye below skin?
Class: Squamata • Lizards • geckos, iguanas, skinks, chameleons • terrestrial, burrowing, aquatic, arboreal • moveable eyelids • Paired copulatory organs • Lower jaw not attached to skull
Class: Squamata • Snakes • Lack limbs • Lack moveable eyelids • Jacobson’s organ • Pit Vipers (heat) • Venom • neurotoxins • hemolytic enzymes
Feeding Adaptations • Teeth curved and pointed inward • Hinged Quadrate bone • Bones of jaw are attached by muscles and ligaments • Moveable palate • Elastic skin • No sternum
Class: Crocodilia • Largest living reptiles • Most closely related to dinosaurs • Complete secondary palate • Four chambered heart • Nest temperature
Dinosaurs and Pterosaurs • Dinosaurs • Ornithischian • Saurischian (closely related to birds) • Pterosaurs • flying reptiles
Class: Aves • Feathers • Hollow Bones • Wings • Endotherm • Organs reduced • Beak without teeth • No bladder
Class: Aves • Wishbone – Called a Furcula made up of the fused clavicles.
Class: Aves • Muscles – • Pectoralis muscle pulls wing down • Supracoracoideus raises wing
The Origin of Birds • Feathers • Beak with teeth • Long Tail • Wing with claw
The Origin of Birds • Sinoauropteryx - protofeathers? • Caudipteryx - true feathers
Bird Classification • 8600 species of bird (28 orders) • 60% are passeriformes (perching birds) • Two major Types • Ratites • Ostriches, Emus • Carinates • Song birds
Hair Endothermic Mammary glands Live birth (2 exceptions) Teeth differentiation Jaw modified to incorporate bones into inner ear Class: Mammalia
The Evolution of the Mammal • Reptile’s lower jaw made up of several bones • Reptile’s middle ear made up of one bone • Mammal’s lower jaw made up of one bone • Mammal’s jaw joint has shifted • Mammal’s middle ear made up of three bones
Mammal Classification • Monotremes • lay eggs • no nipples
Mammal Classification • Marsupials • born early • develops in pouch
Mammal Classification • Placentals • Eutherian mammals • development in uterus joined by placenta