Transcript File
“Never grow a wishbone where your backbone ought to be” -Clementine Paddleford Origin of Tetrapods, Amphibians and Reptiles Chapter 34 Origin of Tetrapods First tetrapods diverged 365 million years ago (________) ________________________a nd shallow inland lakes with muddy bottoms likely selected for early tetrapods Origin of Limbs Tetrapod limbs were modification of preexisting body plan Single appendicular bones (humerus and femur) articulate with pectoral or pelvic girdles Mesomeres deviate from _______ _____ Become larger and stronger Diversification of limb bones _______________ separate tetrapods from fins of lobe-finned fish Evolution of Tetrapods Increased air breathing capabilities More efficient lung Gill arches move to _________ Limbs with digits support tetrapod’s weight on land Evolution of a _____________ separated head from body Separation of ______________ form skull Allowed for head movement Supports fore limbs Fusion of pelvic girdle to spine Transfers forces from hind legs to body Evolution of Tetrapods Eusthenopteron Prehistoric Sacopterygian Early forelimb bones Humerus Radius and ulna Internal nostrils Pectoral girdle bones attached to skull Acanthostega Recognizable limbs Sturdy forelimb bones ___________________ present Eight digits on each hand Fore limbs could not bend forward or support weight Pectoral girdle bones ______________ Evolution of Tetrapods Ichthyostega Reinforced ribcage Limbs ___________ Support weight on land Limited movement on land _____________ present Gills used primarily for respiration Limnoscelis Early amphibian Sturdy pelvic and pectoral girdles Sharp teeth Terrestrial predator Evolution of Tetrapods: Tiktaalik Mid to late Devonian (~380 mya) Tetrapod characteristics Independent ___________________ Ribs to support weight Front fin bone structure similar to all tetrapods Limbs bent at elbow and knee Flat skull with eye on top of head Fish characteristics _____ Scales Fins Class Amphibia Amphibians (Frogs, Salamanders, Caecilians) Approximately 6,150 species Diverged in the late Devonian Most go through metamorphosis (“two lives”) __________ eggs: jelly like eggs with ~50% yolk Thin, highly vascularized skin Aquatic, gill breathing larvae Terrestrial, lung breathing adults Scaleless (except Caecilians) Cutaneous respiration Poison glands _________________ heart Ectothermic Class Amphibia, Order Anura Frogs and Toads “without a tail” ~ 5,400 species Short fore limbs and long hind limbs long Frogs = smooth skin “Toads” = rough, warty skin Modified for jumping Head and trunk fused Tongue attached to front of mouth _______ fertilization Vocalizations in males ________ membrane Amphibian Metamorphosis Egg development: 6-21 days Metamorphosis: 0-7 days: tadpole feeds on yolk then attaches to substrate, breathes through external gills 7–28 days: tadpole swims freely feeding on aquatic vegetation, breathes through internal gills 4-6 weeks: ___________, skin grows over operculum 6-9 weeks: __________ from buds 10-12 weeks: froglet with small tail 12-16 weeks: adult frog Class Amphibia, Order Urodela Salamanders and Newts “bearing a tail” ~ 550 species Carnivorous Legs usually at _________ to body Prefer dark, damp terrestrial habitats ______ fertilization Spermatophore: packet of sperm Smooth skin, except newts Blunt nose and tails typically flattened on sides Class Amphibia, Order Apoda Caecilians “without legs” Secondary adaptation ~ 170 species ___________ diggers Tropics and subtropics Scales in some Sensory tentacles on head Internal fertilization 25% oviparous 75% viviparous Amphibians as Ecological Indicators _______________: a species whose presence, absence of abundance can be used to assess the biological condition or health of a particular ecosystem 1/3 of amphibian species are at risk of extinction Characteristics that make amphibians good indicators Aquatic and terrestrial habitats Metamorphosis Breathe with gills and lungs ________ Cutaneous respiration Susceptible to environmental contaminants (chemicals) ___________ lack shell Integral part of the food chain Herbivorous tadpoles and carnivorous frogs and toads Amniotes Amniotic egg: allowed for embryos to develop in terrestrial environment without __________________. Two major lineages Diapsids: Reptiles, including birds Synapsids: _________ Amniotic Egg Amnion: inner membrane filled amniotic fluid, which cushions the embryo Yolk sac: sac containing nutrients (yolk) for the developing embryo _______: membrane that facilitates gas exchange between the embryo and the air Allantois: sac that collects _________ _______ produced by the embryo Anapsids, Synapsids and Diapsids Based on number of temporal openings (fenestra) Orbit (eye socket) ____________ attachment Anapsid: no temporal openings Turtles Synapsid: single temporal opening ___________ Diapsid: two temporal openings Reptiles including birds Temporal fenestra Evolutionary History of Reptiles Rise in reptiles associated with decline in __________ ~315mya (Carboniferous) Permian dominated by parareptiles, which were large, stocky herbivores Permian-Triassic Extinction followed by evolution of Archosaurs (crocodilians, dinosaurs, pterosaurs) and Lepidosaurs (lizards, snake, tuataras) Most Archosaurs extinct by end of Cretaceous Squamata radiation during Cenozoic Testudines origin __________ Class Reptilia Diverged ~ 310 mya (Carboniferous) Scales made of ________ Internal fertilization Most oviparous Lay eggs on land Ectothermic, poikilotherms Incomplete ________ Four orders Testudinata (turtles) Squamata (snakes and lizards) Crocodillia (crocodiles and allies) Rhynchocephalia (tuataras) Characteristics of Amphibians and Reptiles Characteristics Amphibians Reptiles Metabolism Ectothermic Ectothermic Skin texture Smooth, thin, permeable skin Tough, scaly skin Breathing Gills and lungs Well developed lungs (thoracic breathing) Reproduction Internal and external fertilization Internal fertilization with copulatory organs Egg Jelly-like egg with no shell Amniotic egg with shell Circulatory system Three-chambered heart Three-chambered heart with chambered ventricle, 4 chambered heart in crocodilians Jaws Weak, used for gripping Strong, used for crushing or gripping Class Reptilia, Order Testudines Turtles and Tortoises Origin remains uncertain _______ skull Bony or cartilaginous shell from fusion of vertebrae and ribs Carapace, Plastron, Scutes Tortoise = terrestrial Turtles = live in or near water Herbivorous and carnivorous Beaks (no teeth) Fused vertebrae Ribs Carapace Neck Two groups Cryptodira Pluerodira Scutes Plastron Class Reptilia, Order Testudines Cryptodira Retract head __________ into shells 12 scutes on plastron Includes most extant turtles Sea turtles Tortoises Pond turtles Class Reptilia, Order Testudines Pluerodira Retract head by __________ to the side 13 scutes on plastron Class Reptilia, Order Sphenodontia Tuataras Two extant species Endemic to New Zealand _______ skull preserved No ears or eardrums ________ of teeth on upper jaw __________ Slow growing, long lived >100 years Temperature of eggs influences sex Parietal eye Class Reptilia, Order Squamata Lizards and Snakes Largest order of reptiles, second largest order of vertebrates Diverged in the Triassic period Snakes evolved from _______ _____ their skin/scales Flexible upper jaw with movable quadrate bone Forked tongue in some ~ 9,000 Chemical reception __________: paired copulatory organ Quadrate bone Class Reptilia, Order Squamata Worm lizards ~ 180 species ________: adapted for burrowing and life underground Usually legless Elongate bodies Rudimentary eyes No outer ears Carnivorous Class Reptilia, Order Squamata Lizards ~6,000 species Legs and external ears Movable _______ Herbivorous and carnivorous Range from 16mm to 3m _________: detach tails Regeneration Good vision All continents except Antarctica Terrestrial, burrowing, aquatic, arboreal Communication and locating Parthogenesis in some Class Reptilia, Order Squamata Snakes ~2,900 species Diverged from lizards All continents except Antarctica Terrestrial, burrowing, aquatic, arboreal _______________ (anal spurs) Lack movable _______ Lack external _______________ Carnivorous Constrictors or venomous Jacobson’s Organ Loreal pits Highly mobile jaws >200 vertebrae Feeding Adaptations in Snakes Teeth curved and pointed inward Hinged ___________ Bones of lower jaw are attached by muscles and ligaments Moveable palate Elastic skin No ________ Sensory Adaptations in Snakes Jacobson’s organ (Vomeronasel organ): olfactory sense organ used to detect _______________ Present in many amphibians, reptiles and mammals Snakes deliver odorants to organ with tongue Heat sensing organs: facial pits lines with thermoreceptors capable of sensing minute changes in temperature _________: pit vipers Labial pits: some boas and pythons Lower jaw transmits ground vibrations to cochlea Nostril Nostril Labial pits Loreal pit Poisonous vs. Venomous Poisonous: toxins that are absorbed or ingested, often secreted by the animal Venomous: toxins that are ________ _______, usually with stingers, or fangs Three families of snakes Vipers, Elapsids, Colubrids Two venomous lizards Gila monster and komodo dragon Toxins ___________: disrupt nerve function Hemotoxin: hemolytic enzymes cause blood clotting Families of Venomous Snakes Viperidae: Puff adders, rattlesnakes, cooperheads, cottonmouths Hollow, ______________ Ellipitcal pupils Hemotoxin venom Elapsidae: Seas snakes, taipans, coral snakes, death adders, mambas, cobras Hollow, fixed fangs Round pupils Neurotoxic venom Colubridae: Boomslang, mangrove snake, vine snake ___________ Most are mildly venomous Class Reptilia, Order Crocodilia Crocodiles, Alligators, Cayman, Gharials Diverged around 85 mya Closely related to birds and dinosaurs Archosaur lineage 5 unwebbed digits front, 4 webbed back Complete ______________ Four chambered heart Foramen of Panizza _________ membrane: transparent third eyelid used for protection or to moisten eye Nest temperature influences sex Alligators vs. Crocodiles Crocodile Lower teeth ______ Narrow, pointed snout Alligator Lower teeth ________ Blunt, rounded snout