The World's Foundations; or, Geology for Beginners · Ch. XVI · Unit 3: Part II: Reptiles, chalk, mammals, ice and people
17. The age of reptiles
Goal: Your child can name and describe several great reptiles of the Middle-Life Period and explain the difference between a mammal and a quadruped.
You'll need
- The book, open to this chapter
- A long tape measure (or a 25-foot tape) and chalk or sticks to mark distances
- A large sheet of paper and a ruler
- A notebook for a "rock journal" and a pencil
What's in the book
Chapter XVI describes the Middle-Life or Secondary Period, when great reptiles ruled land, sea and air: huge crocodiles, swimming saurians, a long-necked sea reptile, flying "dragons", giant turtles and the bird-like dinosaur. It tells of thousands of footprints in the Connecticut Valley, a fossil bird with feathers from Bavaria, and the first small mammals.
The lesson, step by step
A question to start
SayDragons only live in fairy tales. Or did something like them once really live?
Read what the author says.
Read the chapter together
Read Chapter XVI (pages 143 to 153). It opens:
It is no fairy-tale which I have to relate ;
Note for you: on pages 145 and 146 Giberne wonders whether a few great reptiles might have lived on into the time of people and started the old dragon stories. She says plainly that this is only her guess.
Meet the reptiles
Make a list in the rock journal with the book's footnote names: Ichthyosaur (fish-lizard with paddles), Plesiosaur (long neck, small head), Mosasaur (long sea "snake"), Pterodactyl (flying reptile with bat-like wings), Dinosaur (crocodile-like and bird-like, sometimes walking on its hind legs). Read:
By a ' saurian ' is meant simply a ' scale-covered reptile.'
Measure them out
Go outside or to a long hallway. Mark out the book's sizes: a river crocodile "forty feet and more", a flying reptile sixteen feet across the wings, a turtle fifteen feet between its flippers. Stand your child at one end. Then draw one of the book's footprints, "twenty inches long", on the big paper and let your child stand in it.
The bird with feathers
Read:
So well had it been preserved, that some of the feathers were there with the bones.
The book also notes that three-toed footprints were at first all thought to be bird tracks, and that dinosaur bones are hollow like a bird's.
Mammal or quadruped?
Crocodiles have four feet, but they are not mammals. Whales and seals and human beings have not four feet, yet they are all included in the Mammal Class.
Quiz: dog (both), crocodile (quadruped only), whale (mammal only), lizard (quadruped only), person (mammal only), horse (both).
Tell it back
Ask: In which "three elements" did reptiles rule, according to the book? (Land, water, air.) Which reptile would you least like to meet, and why?
What we know now
The great dinosaurs died out about 66 million years ago, and no dinosaur bones have ever been found in rocks younger than that, so people never lived alongside them. But birds are living relatives of the dinosaurs: the feathered fossil from Bavaria, named Archaeopteryx, was an early clue. Many dinosaurs were probably warm-blooded, as some already suspected in Giberne's day. Ichthyosaurs, plesiosaurs, pterosaurs and mosasaurs were reptiles but not dinosaurs; mosasaurs were giant sea lizards with flippers, not snakes.
Afterwards
Notice it this week: watch a bird walk and look at its feet and scaly legs. Compare its three forward toes with the dinosaur footprints in the book.
Answers to the book's problems
Land, water and air. A quadruped is any four-footed animal; a mammal is one that feeds its young on milk. Some animals are both (dog, horse), some are only quadrupeds (crocodile, lizard), and some are only mammals (whale, seal, people).
Worked out for this site from the scan. If a number in your copy differs, trust the book.