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32 Cards in this Set

  • Front
  • Back
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
-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
-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
-an organism (Reptile)that evolved two major adaptations
An amniotes two major adaptations were
-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
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
-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
-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.
-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
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
-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
-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
-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
-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.
-group of great flightless birds.

-South America-Rhea

Australia-Emus and Cassowaries

New Guinea-Cossawaries
More locations for Ratites

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
-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.