History of Reptiles Reptiles arose from amphibians Earliest fossils 359 mya Small four legged vertebrates wsmall teeth Pangaea Drier climate Mass extinction during Paleozoic era Diversified to fill niches left by extinct species ID: 661017
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Slide1
Reptiles
Origin and EvolutionSlide2
History of Reptiles
Reptiles arose from amphibians
Earliest fossils 359
m.y.aSmall, four – legged vertebrates w/small teethSlide3
Pangaea
Drier climate
Mass extinction during Paleozoic era
Diversified to fill niches left by extinct speciesMesozoic era “Age of Reptiles”Slide4
Evolution of Dinosaurs
235
m.y.a
dinosaurs dominated the earthEvolved from thecodontsExtinct group of crocodile – like reptilesPangaea separated climates changed dinosaurs became extinct, while new species flourishedSlide5Slide6
Evolution of Dinosaurs (Triassic)
Oldest known fossils
Small carnivorous dinosaurs replaced
thecodontsSuccessful becauseLegs directly under body
Good support, more agile, fast runners
W
ell adapted for dry conditions
Mass extinction of
thecodonts
and large amphibians reduce competitionSlide7
Extinction of Dinosaurs
Asteroid Impact Hypothesis
Multiple Impact HypothesisSlide8
Success of Reptiles
Four modern orders of reptiles
Chelonia
(turtles and tortoises)Squamata (lizards and snakes)Crocodilia (crocodiles, alligators, caimans)
Rhynchocephalia
(tuataras)Slide9
Success of Reptiles
Watertight skin
Keratin
RespirationLungsExcretionUric acid requires little waterAmniotic EggSlide10
Amniotic Egg
Reptiles considered the first terrestrial vertebrate
Amniotic egg
First evolved in reptiles but also found in mammals and birdsProtection from physical damageLimits evaporation of water
Diffusion of O
2
and CO
2Slide11Slide12
Internal Structure of Amniotic Egg
4 specialized membranes
Amnion
Thin membrane encloses the fluid where embryo floatsYolk sacEncloses the yolk, fat – rich food supply for embryo
Allantois
Stores wastes produced by embryo
Chorion
Surrounds all other membranes
Albumen
Protein and water for embryoSlide13
Body Systems of Reptiles
Circulatory System
Two loops
Heart structure and functionTwo atria and a single ventricle (except crocodiles)Divert blood from lungs when inactiveConserves energy
May help raise body tempSlide14
Respiratory system
Lungs are large
Divided into chambers (alveoli)
Increases surface areaFilled by expanding rib cageSnakes right lung enlarged, left obsoleteSlide15
Nervous system
Brain
Sight detect light
HearingTympanum (eardrum) and columellaSnakes lack tympanum (low frequency sounds)
transmitted to the bones of the jaw
Jacobson’s organ
Roof of mouth in reptiles (crocodiles and most turtles)
Sensitive to odors
Pit VipersSlide16Slide17Slide18
Thermoregulation
Vertebrates regulate body heat in two ways
Ectotherm
Warms the body from the environmentEndothermGenerates heat as needed to warm body
Behavior
Require little energy and 1/10
th
food as endotherms same sizeSlide19
Reproduction and Parental Care
3 patterns among reptiles
Differences based on how long the eggs remain within the female and how nutrition is provided to themSlide20
Reproduction
Oviparity
Deposits egg in environment
OvoviviparityMay be laid shortly before hatching or hatch inside femaleViviparity
Shell does not form around egg and young are retained within female