Class Reptilia

Class Reptilia - Class Reptilia Latin word repto to creep...

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Class Reptilia: Latin word “repto”: to creep First true terrestrial animals. As a group they live in a variety of habitats, o both aquatic and terrestrial. They are a very accomplished group o over 7,000 species. About 300 in US and Canada Reptiles most well known for what they were at one time. o Dinosaurs of the Mesozoic Age of reptiles lasted about 160-170 million years. o Gigantosaurus: fossil form in Argentina about 45ft in length. 8-10 tons. 10% longer and 3% heavier than t-rex 4 orders that remain in the class reptillia o Order squamata Most successful group Lizards and snakes Green anole, fence lizard, eastern hognose snake, etc. o Order Crocodilia or Loricata Been around 200 million years Basically unchanged American Alligator, crocodile, etc. o Order Testudines /Chelonia Turtles Have changed very little from their very early ancestors. o Order Rhynchocephalia
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Sphenodon/ tuatara (Page 178) Primarily unchanged from their The only survivor of this group found in New Zealand Characteristics o Skin “Exoskeleton” of horny epidermal scales called osteoderms Alligators have bony dermal plates sometimes called scutes. Dry and scaly Snakes have very dry skin with well developed scale Almost a glandless skin Skin resist drying out and o Production of a shelled or amniotic egg Referred to as a cleidoic egg Lay eggs on the land Major evolutionary step forward Complete move out of the water and onto the land o Limbs When they have limbs they are paired 5 toes Well adapted for running, climbing, and other forms of locomotion Those in water well adapted for paddling and moving through water o Size Diversity of habitat and shapes Some compact like turtles and others elongated like pythons. o Skeleton Completely boney and well ossified
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Ribs coming attached to breast bone or sternum Well-developed thoracic basket protecting the internal organs Skull has Occipital Condyle: bone in the back of the skull Allows them to rotate the head and neck with more dexterity than a mammal Framing magnum is a hole that is supposed to be open at the back of the skull: where the spinal cord passes into the skull. Reptiles only have one occipital condyle like birds o Stops the head from moving too far, but since they only have one they have large versatility in head motion. Articulate condyles Rounded bump o Respiration Primarily through lungs No gills present Brachial arches present in embryos. Many reptiles use cloacae to respire Many turtles have vessels in the cloacae that can get oxygen so they don’t have to come up o Circulation 3 chambered heart like amphibians two atrium and 1 ventrical?? Crocs have 4 chambered heart. 2 atrium, 2 ventricles, and 2 ventricle
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This note was uploaded on 09/19/2011 for the course 1 101 taught by Professor Larrydavid during the Spring '11 term at South Carolina.

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Class Reptilia - Class Reptilia Latin word repto to creep...

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