Note for Readers

This ebook serves as an educational book. If a person is interested to learn more or get in-depth details, please get expert advice from Shark Conservationists.

Introduction

Through this ebook, we will take you on a journey through the wonderful world of 500+ sharks that have existed in all the oceans and seas on Earth for at least 400 million years.

 

You will be able to learn facts about the history and evolution of sharks but also about prehistoric sharks. The important role of sharks in our oceans, and contact with humans. As their anatomy and their senses. Their reproduction, some information about the species of sharks, their classification but also about the threats of sharks.

History and Evolution of Sharks

1. Sharks have been in our oceans for over 400 million years. Some of the shark discoveries date back to the Devon period (420 - 358 million years).
   
   
2. Sharks survived five mass extinctions. These extinction events killed life on earth. The last mass extinction was about 65 million years ago, where it killed the dinosaurs.
   
   
3. Some of the sharks we can see and dive today have not changed for over 150 million years. Sevengill sharks can be detected 190 million years ago.
   
   
4. Sharks can be one of the most important species on Earth. They hold our oceans healthy for over 400 million years.
   
   
5. Sharks have evolved and changed a lot in these millions of years in our oceans. But many sharks still retain some of the same characteristics of sharks that existed millions of years ago.
   
   
6. Probably one of the most advanced sharks today is the hammerhead. They have an advanced sensory system and body shape that has been adapted to hunt specific prey.
   
   
7. The newest species of shark is the hammerhead, which evolved 20 million years ago.
   
   
8. The word "shark" was first mentioned in England in 1569. Before the English used the term "dogfish", which is still sometimes used, usually by fishermen in various countries around the world.

Prehistoric and Extinct Sharks

1. One of the oldest known species of sharks is the Cladoselache. The fossils of this 1.8-meter shark are over 400 million years old.
   
   
2. It is estimated that at least ten shark families existed during the Devonian Period (400 million years ago). Later in history, these families branched out to become other species.
   
   
3. Stethacanthus was a shark that lived 345 to 280 million years ago. This shark had a fascinating dorsal fin that was flat and covered with large scales.
   
   
4. Megalodon was the largest shark-predator in history, where it disappeared about 2.6 million years ago. It is estimated that it was between 12 and 21 meters! And his teeth were about 18 cm long.
   
   
5. The shark Helicoprion lived 290 million years ago and had a strange spiral jaw structure that

   Impressum

   Verlag: BookRix GmbH & Co. KG

   Tag der Veröffentlichung: 18.03.2021
   ISBN: 978-3-7487-7752-6
   

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