Readers start with the Holocene epoch which began approximately 10,000 years ago and is the most recent in the Cenozoic era. During this time, humans evolved, the Earth warmed resulting in the retreat of vast ice sheets. This allowed humans to migrate and settle in most parts of the world.
The Pleistocene which began approximately 2.6 million years ago saw the most recent ice age. With climate cooling, ice caps formed at the North and South poles. There were interglacial periods when the climate warmed allowing forests and mammals to flourish. It was a time of saber tooth cats such as Smilodon. Prior to this, during the Neocene epoch (23 million to 2.6 million years ago), mammals began to dominate the Earth.The Neocene was preceded by the Paleocene which began 66 million years ago. The climate was warm allowing large rain forests to grow and new types of mammals to evolve. Early primates began living in the trees during this time.
Before the Paleocene, the Cretaceous Period saw the reign of the dinosaurs which were a very diverse group of animals. There were meat-eating dinosaurs such as Tyrannosaurs, as well as plant-eating ones such as Spinops. Flowering plants or angiosperms also developed during the Cretaceous Period providing fruits as a food. In the sea, giant mosasaurs, turtles and ammonites flourished. Scientists have evidence that the Cretaceous experienced a mass extinction even that destroyed seventy percent of the life on Earth. The cause is believed to be an asteroid that crashed in what is now Mexico, resulting in the Earth being overwhelmed with dust and smoke, blotting out the sun. This catastrophic event is believed to be responsible for the demise of the dinosaurs.
It was during the Jurassic, 201-145 million years ago, that the largest land animals developed. These were the sauropods. During this time, the super continent known as Pangea began to break up. This began with the break up of North America from Europe and Asia and later Africa from South America.
About 252 million years ago, the ancestors of dinosaurs and other reptiles were evolving. At this time dinosaurs were small, inhabiting most areas of Pangea.
The Permian period (299- 252 million years ago) saw the formation of the supercontinent called Pangea from the collision two great land masses. At this time there were amphibians, reptiles and pre-mammals. Most were predators who ate other predators.Although there were many plants, they were consumed mostly by insects. The end of the Permian is characterized by a great extinction resulting from an extended period of widespread volcanic activity. It is believed over ninety percent of life on Earth was destroyed.
Before the Permian, the Carboniferous was a time of giant trees and towering ferns. These lush forests were filled with many different arthropods, amphibians and the first reptiles.From 419 to 359 million years ago, the Devonian period saw the development of the first trees and forests, the first insects and spiders and the first four-legged animals such as salamanders. Prior to the Devonian, during the Silurian (443 to 419 million years ago), temperatures on Earth were slowly rising, allowing new life forms to develop. The first fish with jaws developed allowing predation to occur, as well as the evolution of eurypterids ("scorpion-like arthropods) which could grow to be very large.
In the Ordovician (485 to 443 million years) most life existed in the oceans. Snails, clams, nautiloids, trilobites and conodonts as well the world's first fish lived in the water. This period was characterized by the expansion of coral reefs across the world. The period before the Ordovician is called the Cambrian and this era saw the explosion of life on Earth. This sudden increase in life forms is called the "Cambrian Explosion". Trilobites, a primitive arthropod, dominated the Cambrian period which is sometimes referred to as the "Age of Trilobites".
Finally, the period before the Cambrian is known as the Ediacaran, some 4.6 billion to 541 million years ago. The amazing story of life on Earth began during this time and little is known about the creatures who lived during this phase.
Discussion
In Prehistoric Dinosaurs, Megalodons and Other Fascinating Creatures of the Deep Past, author Zoehfeld has chosen to tell the story of life on Earth beginning with the modern epoch of the Anthropocene (which we are now living in) and moving backwards through time to the very beginning. This makes it difficult to fully understand how life developed from simpler forms to more complex ones, how the climate and the land masses changed over time and how catastrophic events shaped life and the world afterwards. Therefore, it is recommended that readers start at the back of this book and read backwards to the front! Reading in this way works superbly, making the timeline of events more logical and understandable.
Zoehfeld's simple text gives readers a good understanding of the changes that occurred through each period and there are detailed, full colour illustrations which provide a sense of what the Earth may have looked like during each time period as well as the creatures that could be found in the seas and on land. The author includes many interesting facts for each period, and sets aside small areas on each page to explain certain events or to provide more details. For example, there are short, simple explanations of how coal formed, supervolcanoes, how dinosaurs walked, mass extinctions, ice ages and many other topics.
This book was produced in association with the Smithsonian's National Museum of Natural History. A more concise title with a more engaging illustration on the cover is also recommended. Overall, an interesting presentation of the development of life on Earth. However, the claim on the book's back cover, "What's the best way to see the past? From the present, of course!" didn't work for this reader!
Book Details:
Prehistoric Dinosaurs, Megalodons, and Other Fascinating Creatures of the Deep Past by Kathleen Weidner Zoehfeld
Greenbelt, Maryland: What on Earth Publishing 2019
45 pp.
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