There was no need for the Brachiosaurus to stretch to reach trees The Brachiosaurus holds the record for being the largest living thing to walk on Earth Unlike other dinosaurs that could run on two legs the Brachiosaurus needed four thick legs to support the weight of its body Early illustrations showed the Brachiosaurus on its two back legs eating leaves from treetops Scientists now believe the front legs held most of the weight The two back legs were not strong enough to hold the dinosaur up The Brachiosaurus had a long neck It was the tallest herbivore of its time It could reach more than twice as high as a giraffe The long neck was a problem for young Brachiosaurus Since they were shorter the neck was THE BRACHIOSAURUS REACHED FOR THE TREETOPS 1 4
easier for predators to bite and pull the dinosaur down Once a Brachiosaurus was at its full height and weight it was intimidating to most other dinosaurs and would have been difficult to attack and kill Brachiosaurus are also believed to have lived and moved in herds Healthy Brachiosaurus would have protected the younger or weaker Brachiosaurus from attack The Brachiosaurus had spoon shaped teeth This helped it eat through pinecones and ferns The Brachiosaurus needed a lot of food each day It ate 440 pounds 200 kg of leaves and twigs every day THINK ABOUT IT Why was the slow-moving Brachiosaurus safe from attack once it was an adult Why is traveling in herds safer than traveling alone 50 Height in feet 15 m of a tree that a Brachiosaurus could reach Pronounced BRAK-ee oh-sore-us When 155 140 million years ago Late Jurassic Period Fossil location United States Size 50 feet 15 m tall 120,000 pounds 54,431 kg The Brachiosaurus is recognizable by the lump on its forehead 5
A small dinosaur ran through the river valley It was the Eoraptor and it was one of the earliest dinosaurs discovered It may have had scales or feathers covering its body The Eoraptor’s back legs were supported by its strong thighbones and muscles Scientists know this dinosaur was a fast and strong hunter The Eoraptor was a carnivore It ate small animals such as lizards and other reptiles The Eoraptor may have also hunted larger animals by attacking them with its sharp claws and teeth The Eoraptor could not hold onto larger prey so it would attack and then retreat and wait for The Eoraptor ran on its back legs THE EORAPTOR WAS A SMALL BUT FIERCE PREDATOR 2 6
DR ROBERT BAKKER Dinosaurs were once thought to be slow-moving reptiles that dragged their tails when they walked Dr Robert Bakker was one of the first paleontologists to change that image He compared dinosaurs with modern-day animals Bakker argued that the Eoraptor and other dinosaurs were intelligent quick-moving and adaptable creatures He has become one of the most famous paleontologists as a result of his theory 1 Number of complete Eoraptor fossils that have been found Pronounced EE-oh-RAP tor When 230 225 million years ago Triassic Period Fossil location Argentina Size 1 foot 0 3 m tall 20 pounds 9 1 kg the prey to weaken Once the prey collapsed the Eoraptor would eat it Although it seems small with a body only three feet 0 9 m long it was large compared to some other dinosaurs at the time The Eoraptor had sharp saw-like teeth and claws It also had large arm muscles and could walk on its back legs Scientists believe the Eoraptor was an ancestor of the fierce Tyrannosaurus rex Eoraptors used their claws to attack prey 7
