Biology Unit 4 Test
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- Evolutionary Advantages of Reptile Ancestors
- -include a skin waterproofed with scales and eggs protected from drying out by a leathery shell.
- Modern Reptiles include
- -the tuatara from New Zealand, turtles, crocodiles, alligators, lizards, and snakes.
- All living Reptiles have
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-scales and depend on the outside environment for their source of heat as opposed to producing their own heat internally.
-gas exchange occurs across the lungs - On the Reptile evolutionary tree
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-the branches lead to mammals, turtles, pterosaurs, dinosaurs, crocodiles and birds
-however, many of the branches also lead to extinct groups, such as aquatic mosasaurs. (Mosasaur found in Onion Creek Texas) - The Archosaurs
- -(ruling reptiles) is a group that contains the traditional dinosaurs, pterosaurs, and all crocodiles and birds.
- Dinosaurs are typically divided into two groups,
- -the "bird-hipped" dinosaurs and the "lizard-hipped" dinosaurs
- The "lizard-hipped" group contains
- -the Tyrannosaurus, Velociraptor, and Apatosaurus
- The "bird-hipped" group contains
- -the stegosaurs and Triceratops
- Amniote
- -an organism (Reptile)that evolved two major adaptations
- An amniotes two major adaptations were
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-an egg that does not need to be laid in water because it contains its own little "pond" inside the shell, and
-a waterproof skin - From the amniotes ancestral stock rose two main lines:
- -one leading to mammals, and the other to reptiles and birds.
- BIRDS are the second most
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numerous group of vertebrates alive today, second in number only to the bony fishes.
-birds are most closely related to crocodiles. - Birds cannot be classified
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-only on the prescence of feathers.
-125 million year old fossils from China show that dinosaurs once had feathers. Bird fossils with the same characteristics were also found in the same deposits. - Thus, many paleontologist use
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-this fossil evidence to show that birds are actually living dinosaurs, meaning that not all of the dinosaurs died out 65 million year ago.
-birds should therefore be classified as dinosaurs. - Archaeopteryx
- -was the first non-controversial bird fossil. It is 145 million years old
- Archaeopetryx had
- -feathers, teeth, a long tail, and was most likely a decent flyer.
- Protoavis was a fossil
- -found in rocks near Lubbock that are 220 million years old.
- Protoavis was originally
- -described as a bird fossil, but it had no feathers, so scientists had to look at bone and skull structures instead.
- Reptile feathers were likely used for
- -insulation, which also supports the idea that dinosaurs were warm-blooded.
- Today, all animals with
- -feathers are birds
- Feathers are used for
- -flight, insulation, and courtship
- Birds are
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warm-blooded and produce their own heat internally
-birds must eat a great deal of food to keep producing heat. - Changes in the Bird body include
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-a heavy jaw that has been replaced with a light-weight horny beak
-a muscular gizzard has been added to the digestive tract. Birds then swallow small pebbles that are used to grind up food. - Birds also have
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-a large intestine that is very short and prevents the bird from storing heavy wastes in its body.
-wastes are released as food is processed by the digestive tract. - The bones of a bird
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-are hollow, which considerably reduces their weight.
-some dinosaurs also had hollow bones - The female bird
- -lays her eggs outside her body and sits on the eggs to provide the developing young with heat.
- The bird egg houses the developing embryo
- -surrounded by a protective calcium-based shell.
- Down Feathers and Contour Feathers
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-Down feathers are modified to trap heat.
-Contour feathers cover down feathers. (are shorter than wing feathers)
-Down feathers trap air between their fluffy fillaments and the contour feathers make a layer over the down feathers to keep the heat next to the bird's body. - Ratites
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-group of great flightless birds.
-South America-Rhea
Australia-Emus and Cassowaries
New Guinea-Cossawaries - More locations for Ratites
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Africa-Ostrich
New Zealand-Extinct Moas
Madagascar-Extinct Elephant Birds
-These birds may have all been part of a supercontinent called Gondwana that eventually broke up into many pieces. - Asteroid Impact Hypothesis
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-created by Walter Alvarez
-says that an asteroid hit the earth 65 million years ago, creating a huge dust cloud that enveloped the earth.
-the dust cloud blotted out the sun, dropping the temperature of the earth and killing off the plants that dinosaurs ate. - Nictitating Membrane
- -the third eyelid of a lizard that slides over the eye to protect it.