Reptiles Ch. 31.1

What is a Reptile? Land vertebrate Well developed skull Backbone and tail 2 limb girdles 4 limbs

2 exceptions: –Snakes (limbless) –Turtles (hard shells that are fused to vertebrate)

Reptiles: dry, scaly skin, lungs, and lay terrestrial eggs with several membranes Live their entire lives out of water

Skin is dry and has thick, protective scales –Scales can be smooth or rough Dry, waterproof skin helps with living in dry environments. –Not always good though. The skin is frequently shed

Reptiles are found widely through the Earth. Very diverse lifestyle and look Can’t live in very cold climates

Evolution of Reptiles Fossils of 1 st reptiles from ~350 mya Earth’s climate became cooler and less humid –Lakes and swamps dried up and reptiles evolved to live in that dry area

Mammal-like Reptiles Displayed a mix of reptilian and mammalian characteristics Dominated many land habitats Went extinct quickly (replaced by DINOSAURS in the fossil record)

Enter the Dinosaurs Late Triassic and Jurassic time periods –Very diverse and large number of reptiles –2 aquatic groups were in the seas –Ancestors of turtles, crocodiles, lizards, and snakes –Dinosaurs were everywhere

Dinosaurs varied in size Quadriped or biped Herbivore or carnivore Lived as ‘families’ Laid eggs Two main groups –ORNITHISCHIA – bird hipped –SAURISCHIA – lizard hipped

Exit the Dinosaurs Mass extinction –Natural disasters: volcanic eruptions, lava flows, dropping of sea level, asteroid in the Yucatan Peninsula Major forest fires and dust clouds

Form and Function in Reptiles Well developed lungs Double loop circulatory system Water conserving excretory system Strong limbs Internal fertilization Shelled, terrestrial eggs Controllable body temperature

Body Temperature Control: ectothermic – rely on behavior to regulate temp. Feeding: wide range of food Respiration: spongy lungs provide more gas exchange Circulation: efficient double loop –Blood to and from the lungs; blood to and from the rest of the body

Heart has 2 atria and 1-2 ventricles Excretion: urine is produced in the kidneys, urinary bladder stores urine and released in the cloaca Response: complex eyes and can see color, good sense of smell, mouth can ‘taste’ chemicals, can pick up vibrations/hear

Movement: legged reptiles have stronger limbs; rotated further under the body; flippers for aquatic turtles Reproduction: internal fertilization; oviparous (lay eggs that develop outside mother’s body) –Eggs have amnion, yolk sac, chorion, and allantois

Groups of Reptiles Lizards and Snakes: SQUAMATA (scaly reptiles) Crocodilians: CROCODILIA (long and broad snout, squat appearance) Turtles and Toroises: TESTUDINES (shell built into the skeleton; carapce [dorsal], platron [ventral] TUATARAS: SPHENODONTA (resemble lizards

Ecology of Reptiles Habitats are endangered Hunting