Biology_2007_Virtual_Lab_Answer_Key-1

4 what evidence supports the hypothesis that birds

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4. What evidence supports the hypothesis that birds evolved from dinosaurs? Birds do not only share feathers with some dinosaurs but also a wishbone, and three fingers on each hand. 5. Describe some features that dinosaurs share with modern living reptiles. Modern living reptiles and dinosaurs can live and reproduce successfully on land, have scaly skins, are ectotherms, and have claws. 6. What information would an artist use to reconstruct a model of a dinosaur? Answers will vary. Fossilized bones and teeth, the position the fossilized bones are found in, footprints and the rare fossil remains of skin, eggs, and intestines give the artist clues about how the animals looked and about their behavior. 7. How could a paleontologist determine that a dinosaur was a plant eater or a carnivore? Paleontologists look for clues by examining fossils of scat (excrement), fossil foot prints, groups of fossils from different dinosaurs, and tooth marks on bones. They also look for adaptations that carnivorous dinosaurs might have such as claws, and teeth for catching, killing, eating, and digesting meat. In dinosaurs believed to be herbivorous they look for adaptations to pull vegetation off a plant, and digestive tracts with special adaptations to digest plant material. 8. What other evidence besides fossil bones might be useful in describing the behavior of a dinosaur? Fossil dinosaur foot prints and tracks can tell about their behavior. For example, they may reveal which dinosaur made the tracks, and how many animals were traveling, hunting, browsing, wading, trotting, and running after prey or from predators.
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Lab 24: Mammals 1. How do the various characteristics of animal skulls indicate the importance of one sense over another? Answers may vary. The jaguar skull has a very small rostrum indicating the cat’s poor sense of smell. However, the jaguar’s orbits are proportionally large for its skull indicating enhanced vision. 2. What skull features do prey animals have in common? The orbital fossa are usually located on the sides of the skull in prey animals. Also, prey animals are usually, but not always, herbivores. Herbivores have a diastema. 3. What skull features do predator animals have in common? The orbital fossa of predator animals are forward facing for distance vision and better depth perception. Predators also have a less lower jaw movement which allows a more forceful bite. 4. What can be learned by studying the dentition of various mammal skulls? The dentition of mammal skulls indicates the types of food eaten by the animal. If the mammal is an herbivore it will have more pronounced incisors, a diastema, and cheek teeth for grinding plant material. If the mammal is a carnivore it will have more prominent canines and cheek teeth for tearing and shredding. Omnivores have prominent incisors and their cheek teeth are a combination of sharp, scissor-like carnassial teeth and teeth with more rounded cusps for grinding and crushing.
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