The Science of Dinosaurs

The Science of Dinosaurs — page 3 — Based on its body proportions scientists believe Spinosaurus lived in the water It may sound as if this is a scene from a movie But Spinosaurus was real It is the earliest known swimming dinosaur and it lived in the waters of northern Africa 97 million years ago How do we know these things No person has ever seen a Spinosaurus in real life But these

The Science of Dinosaurs — page 4 — creatures left behind bones eggs and footprints Some of these things formed into fossils A fossil by itself looks like a funny-shaped rock But fossils contain secrets To reveal those secrets we use science Scientists can discover which animal formed a fossil and how that animal lived Science provides a window into the past It allows us to learn about animals that died tens of millions of years ago Dinosaur science is part of a discipline called IN THE REAL WORLD A Fossil Birthday Cake As layers of dirt sand and debris collect on the ground the old ground gets covered up Over millions of years heat and pressure turn the old ground into rock Sometimes animals or plants that died and fell to the ground also get covered up and become fossils The rocks and fossils form a stack of layers called strata At the Blue Nile Gorge site in Ethiopia the Nile River cut through these strata like someone slicing into a birthday cake Scientists have found fish scales pieces of turtle shells and dinosaur teeth The layer a fossil comes from reveals the time period in which that animal lived and died 7

The Science of Dinosaurs — page 5 — paleontology and the people who study dinosaurs are paleontologists A Dinosaur Time Machine Imagine a time machine could take you back to see your favorite dinosaurs You would have to take many separate trips to see all of them Dinosaurs roamed Earth for a very very long time 185 million years During this time span many new dinosaurs appeared They evolved from earlier animals Some of these new dinosaurs eventually died out Others evolved into even more new forms Other creatures including giant sharks early birds and small mammals shared the planet with the dinosaurs Scientists divide up Earth’s history into chunks of time The time of the dinosaurs is called the Mesozoic era It contains three smaller chunks the Triassic Jurassic and Cretaceous periods The Mesozoic era came to an end about 66 million years ago when approximately half of all species on the planet went extinct To understand how long dinosaurs ruled 8

The Science of Dinosaurs — page 6 — ERA PERIOD 66 C r e t a c e o u s J u r a s s i c T r i a s s i c M e s o z o i c o g A s r a e Y f o s n o i l l i M 145 201 252 66 MILLION YEARS AGO 200 MILLION YEARS AGO 250 MILLION YEARS AGO A Changing World Scientists divide the Mesozoic era into three chunks of time called the Triassic Jurassic and Cretaceous periods At the beginning of the Mesozoic era all of the continents were squashed together into one giant landmass called Pangaea Slowly they moved apart to where they are now How has the land shifted from the end of the Mesozoic era to today 9

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