Jill Keppeler - Sharks Lived with the Dinosaurs!

Please visit our website, www.garethstevens.com. For a free color catalog of all our high-quality books, call toll free 1-800-542-2595 or fax 1-877-542-2596.Cataloging-in-Publication Data Names: Keppeler, Jill. Title: Sharks lived with the dinosaurs! / Jill Keppeler. Description: New York : Gareth Stevens Publishing, 2017. | Series: Living with the dinosaurs | Includes index. | Sharks, Fossil--Juvenile literature. | Sharks, Fossil--Juvenile literature.

Classification: LCC QL638.9 K47 2017 | DDC 597.3--dc23 Published in 2017 by Gareth Stevens Publishing 111 East 14th Street, Suite 349 New York, NY 10003 Copyright 2017 Gareth Stevens Publishing Designer: Laura Bowen Editor: Therese Shea Photo credits: Cover, p.. All rights reserved. No part of this book may be reproduced in any form without permission in writing from the publisher, except by a reviewer. Printed in the United States of America CPSIA compliance information: Batch #CW17GS: For further information contact Gareth Stevens, New York, New York at 1-800-542-2595. CONTENTS Words in the glossary appear in bold type the first time they are used in the text. A LONG, LONG TIME AGO When you think of creatures from a very long time ago, you probably think of dinosaurs.

These ancient into other animals. Another amazing animal swam in Earths oceans millions of years before dinosaurs existedand forms of that killer creature still live today. Lets learn about sharks! THERE ARE BIGGER CREATURES IN THE OCEANS, BUT SHARKS HAVE MANY THAT MAKE THEM THE KINGS OF THE SEA. MORE THAN 400 SPECIES, OR KINDS, OF SHARKS ARE ALIVE TODAY. THE FIRST SHARKS? No one is sure when sharks first appeared. Theres evidence the first sharklike fish lived more than 400 million years ago.

Sharks then were different from the sharks of today. The early shark Cladoselache (klad-uh-SEHL-uh-kee) had a mouth at the front of its head rather than on the bottom of its head, as sharks today have. Modern sharks first appeared during the Jurassic period, which began about 200 million years ago. By the Cretaceous period, which began about 145 million years ago, sharks looked much like they do today. THE PREHISTORIC WORLD Some dinosaurs were smaller than the sharks that lived during the same time. Compsognathus (kahmp-SAHG-nuh-thus) was one of the smallest dinosaurs.

It grew about as tall as a chicken, but was about 2 to 3 feet (0.6 to 0.9 m) long. MOST ANCIENT AND ALL MODERN SHARKS HAVE TOOTHLIKE SCALES FOR PROTECTION. HOWEVER, CLADOSELACHE DIDNT HAVE THESE SCALES. IT HAD A SHORT, ROUNDED , TOO. THE TOOTH IS OUT THERE Scientists have discovered about 1,000 species of dinosaurs so farbut theyve found 2,000 to 3,000 species of prehistoric sharks! Theyve learned a lot about these sharks because of something the sharks left behindtheir teeth. A sharks skeleton is made of .

Fossilized teeth can tell a scientist how big a shark was, where it lived, what it ate, and how long ago it lived. THE PREHISTORIC WORLD The earliest known shark teeth are from 400 million years ago. They had two points and were very small. SHARKS LOSE AND REPLACE THOUSANDS OF TEETH OVER THEIR LIFETIME. THATS ALSO A USEFUL ADAPTATION FOR MEAT EATERS! BAD BITERS One shark that shared Earth with the dinosaurs was Hybodus (HYB-uh-duhs). Hybodus also had a bony blade on its back fin to warn off predators. Cretoxyrhina (kreh-tox-ee-RY-nuh) appeared about 100 million years ago. Cretoxyrhina (kreh-tox-ee-RY-nuh) appeared about 100 million years ago.

Also called the Ginsu shark, the creature got this nickname because of its teeth. The word Ginsu is the name of a supersharp knife. THE PREHISTORIC WORLD Sharks from the group Xenacanthus (zee-nah-KAN-thus) looked like eels with a spine sticking out of their head! CRETOXYRHINA, OR THE GINSU SHARK, COULD GROW UP TO 24 FEET (7.3 M) LONG. PREDATORS AND PREY Sometimes, dinosaurs ate ancient sharks. Spinosaurus (spyn-oh-SAWR-uhs), a huge dinosaur that lived about 95 million years ago, could swim and probably enjoyed dining on sharks. Mosasaurs (MOH-suh-sawrz), reptiles that swam in ancient oceans, also probably ate sharks.

Sometimes, sharks ate dinosaurs! Scientists have found ancient shark teeth in fossilized dinosaur bones. So far, theres no evidence that sharks killed the dinosaurs they ate. However, that doesnt mean it never happened. Sharks swam through rivers and lakes that dinosaurs might have drunk from. MOSASAURS WERENT DINOSAURS, BUT THEY WERE BIG. THEY COULD GROW UP TO 50 FEET (15 M) LONG! THE PREHISTORIC WORLD Spinosaurus was one of the largest meat-eating dinosaurs to ever live on Earth.

This creature lived in North Africa. It had long spines growing out of its back to form a body part that looked like a sail. THE SCAVENGER Squalicorax (skwal-ih-KOHR-ax) lived during the same time as Cretoxyrhina, about 100 million years ago. Some scientists think Squalicorax was probably a scavenger, or an animal that eats . Thats why Squalicorax is sometimes called a crow shark. Scientists believe Squalicorax was a scavenger because theyve found this sharks tooth in mosasaur remains.

The reptile was likely dead before the shark found it. Scavenging would have helped Squalicorax survive during times when it was hard to find live prey. THE PREHISTORIC WORLD In 2015, a team of scientists announced the discovery of Pseudomegachasma (soo-doh-mehg-uh-KAS-muh), which lived about 100 million years ago. This shark had a huge mouth and ate tiny sea creatures. It had lots of very small teeth. REMAINS OF A SQUALICORAX WERE FOUND IN KANSAS! WE KNOW MUCH OF THIS LAND WAS ONCE UNDERWATER.

ESCAPING EXTINCTION Throughout the history of Earth, there have been five mass events, which are fast and widespread losses of life across the planet. The mass extinction event that occurred about 65 million years ago led to the extinction of the large dinosaurs, and about 80 percent of animal species! Sharks have survived all five of these terrible events. What makes sharks such great survivors? Adaptations are the key. Sharks passed on features and that helped them live in their watery worlds. THE PREHISTORIC WORLD Although they werent dinosaurs, ichthyosaurs (IHK-thee-uh-sawrz) and plesiosaurs (PLEE-see-uh-sawrz) were large reptiles during the time of the dinosaurs. They shared waters with sharks.