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Reptiles Chapter 41
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Origin & Evolution of Reptiles
Section 41.1
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History of Reptiles 350 million years old
Reptiles arose from amphibians “Age of Reptiles” = Mesozoic era Reptile means “to crawl” Herpetology: study of reptiles & amphibians
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Evolution of Dinosaurs
Dinosaurs: group of extinct reptiles that dominated life 235 mya Triassic dinosaurs: small, carnivorous Jurassic dinosaurs: large, carnivorous Cretaceous dinosaurs: large, herbivorous
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Extinction of Dinosaurs
66 million years ago Asteroid-impact hypothesis: huge asteroid hit the earth, creating lots of dust that reduced the amount of sunlight causing massive climatic changes Multiple-impact hypothesis: multiple asteroid impacts Video
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Real reason
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Success of Reptiles Only 4 orders of reptiles survived the mass extinction Squamata, Chelonia, Crocodilia, & Rhynchocephalia First totally terrestrial vertebrate
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Amniotic Egg Egg that encases the embryo in a secure, self-contained aquatic environment
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Draw this picture!
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Parts of the Egg Amnion: membrane enclosing the fluid where the embryo floats Yolk sac: encloses the yolk (fat-rich food supply) Allantois: stores wastes produced by embryo Chorion: protects the embryo Albumen: stores protein & water for embryo
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Characteristics of Reptiles
Section 41.2
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Watertight Skin Thick, dry skin with keratin: Lipids & protein barrier
protein found in the outer surface cells Lipids & protein barrier Protects from water loss, infections, & injuries
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Excretion Efficient systems to help conserve water
Little water loss in urine Lungs to breathe out CO2
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Circulatory System Composed of two loops:
Pulmonary loop: deoxygenated blood from heart to lungs, oxygenated blood from lungs to heart Systemic loop: oxygenated blood to body, deoxygenated blood to heart
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Heart Structure & Function
Most have a 3 chambered heart: 2 atria & 1 ventricle (partially divided) Crocodiles have a 4 chambered heart: 2 atria & 2 ventricles Ventricle divided by septum tissue Reptiles can reroute blood flow away from lungs Conserves energy Raises body temperature quickly
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Crocodile Heart Septum
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Respiration Large, several chambered lungs with small sacs called alveoli Increases surface area for diffusion First vertebrae group to breath by expanding & contracting their chest Air pressure gradient between outside and the thoracic cavity
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Nervous System Sight is very important thus big eyes
Hearing is also important though snakes lack a tympanum Detect ground vibrations via jaw bones Jacobson’s organ: detects odor (smell), on roof of mouth Heat sensitive pits below eyes of some snakes
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Thermoregulation Definition: control of body temperature
Ectotherm: warms body by absorbing heat from the surroundings Fish, reptiles, amphibians Endotherm: generates heat from within Birds, mammals
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Advantages & Limitations of Ectothermy
Slow metabolism Less food needed Limitations: Cannot live in cold climates (become dormant in winter) No sustained exertion
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Reproduction & Parental Care
Oviparity: egg surrounded by tough protective shell, no parental care Ovoviviparity: eggs stored within female until just before hatching, limited parental care Viviparity: eggs stored with female and receives nutrients from the placenta, most parental care
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Welcome to the world!
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Modern Reptiles Section 41.3
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Order Chelonia Examples: turtles (water dwelling) & tortoises (land dwelling) Body covered by a 2 part shell: carapace (dorsal) & plastron (ventral) Vertebrae & ribs fused to carapace Cannot leave shell! Sharp beak with no teeth Lay eggs (oviparity)
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Two parts of the shell Some Ohio turtles on the next few slides…..
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Eastern Box Turtle
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Stinkpot Musk Turtle
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Soft-shelled Turtle
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Blanding’s Turtle
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Spotted Turtle
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Snapping Turtle
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Painted Turtles
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Tasha, Daisy, & Bowser – in the Maroons’ house!
Video
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Order Crocodilia Examples: crocodiles & alligators
Closest relatives to dinosaurs All are carnivores Eat turtles, fish, etc.
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Order Squamata Examples: lizards & snakes
Autotomy: the ability to detach a body part often when a predatory is near Snakes swallow prey whole Detachable jaw
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Types of Snakes Constrictors: wrap body around prey and suffocate by increasing pressure Boas, pythons, anacondas Elapsid: inject venom through two small, fixed fangs in front of mouth Cobras, coral snakes Vipers: inject venom through large, mobile fangs in the front of mouth Rattlesnakes, copperheads, water moccasins
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Order Rhynchoephalia Example: tuatara Meaning “spiny crest”
Only two modern species Live in New Zealand
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4 Order Note Cards Front Side: Back Side: Name of order
Picture (in color) of animal Back Side: Example organisms Where on Earth?/habitat Unique characteristics Feeding patterns Reproductive behavior
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