Fossils and Paleogeography

The distribution of plant and animal species in the world today reflects the interplay between the physical environment, which, for example, restricts polar bears to the high latitudes, and geographical barriers to migration, which, for example, have kept polar bears from invading the Antarctic and keep the marine snakes of the Pacific side of Panama from invading the Caribbean Sea. Such barriers divide the world into bio-geographic provinces. The fossil record enables paleontologists to reconstruct such provinces for the past and to study their history. South America, for example, was joined to Africa during most of the Mesozoic Era, as its Triassic and Jurassic reptile faunas demonstrate. When it broke away, in mid-Cretaceous time, with the opening of the South Atlantic Ocean, the dinosaurs of South America succumbed to the Cretaceous crisis and the mammals took their place as the dominant land animals, forming a very different kind of mammalian fauna that evolved independently of the Eurasian-American fauna. Australia underwent similar changes except that it remained isolated, and its indigenous mammalian fauna (a marsupial one) has evolved to its modern state. South America became linked with North America during the Pliocene Epoch, and the two very different mammalian faunas invaded each other's territories, pitting species against species for existence. Eventually, North America assimilated some South American mammals (ground sloths, armadillos, opossums, and porcupines), but the majority of South American species became extinct.

The fossil record also shows that the Caribbean and eastern Pacific marine faunas were essentially identical in Miocene times, diverging only since the Panamanian land bridge closed in Pliocene time. The question of whether to build a Panamanian sea-level canal has focused attention on what would happen to present faunas if communications were to be reestablished. Would the Pacific sea snakes, for example, invade the Caribbean to the detriment of fisheries there?

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  	Bones, Bones, Dinosaur Bones by Byron Barton Use high-quality literature to observe nature and encourage children to act and think like scientists. $24.95 Big Book | Grades Pre-K-3

  
  Bones, Bones, Dinosaur Bones
  Grades Pre-K-3 $24.95
  
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  Dinosaur Teeth by Susan H. Gray REVIEWS:   10/1/07 Library Media Connection With its fabulous photography and large print, this content vocabulary building set gives our youngest paleontologists a fine introduction to all things dinosaur while providing a motivating framework for learning to read nonfiction. In each book, a word hunt immediately follows the table of contents, giving children new words with a pronunciation guide and a corresponding photo. Children learn the vocabulary as they read, $14.00 You save: 30% Library Binding | Grades 1-2

  
  Dinosaur Teeth
  Grades 1-2 $14.00
  

What Color Were the Dinosaurs?
Scientists' theories vary about what color skin dinosaurs may have had.

What Did Dinosaurs Eat?
Scientists can tell whether a dinosaur was a plant-eater, a meat-eater, or both, by studying its teeth.

Digging Dinosaurs
Dinosaurs didn't just walk the Earth long ago -- they lived underground too! That's what scientists learned when they discovered the first species of a burrowing dinosaur. The discovery will go on display this summer at Montana State University's Museum of the Rockies.