The Triassic Period (250 million years ago): Here you will collect information about dinosaurs During the Triassic Period, all earths land formed a single continent called Pangaea. Pangaea was close to the equator. The weather was hot; heavy rainstorms swept parts of the single continent, while other areas were dry. Giant ferns and other primitive trees without flowers towered over the land.
Reptiles were the dominant form of life in the Triassic period. Many reptiles were not even closely related to dinosaurs. But some had similar feature
s. The rabbit-size Logosuchus modified ankle bones helped it walk upright, the same way dinosaur ankles did. Some Triassic reptiles, such as Saurosuchus, grew to more than 20 feet (6.5 meters) long, longer than most Triassic dinosaurs.
The earliest dinosaurs we know of were dog size meat eaters from the Late Triassic period such as Eoraptor from Argentina. The largest of these early dinosaurs was Herrerasaurus, a meat eater 15 feet (4.5 meters) long.
Two very different form of dinosaurs, the saurischian and the ornithischian, developed during the Triassic Period. These forms survived through the rest of dinosaur time.
The saurischian, or lizard-hipped, dinosaurs had a pubis bone that faced down and forward in its hips. Saurischians included both the meat eating theropods and the giant four legged plant eating sauropods.
Ornithischians, or bird hipped, dinosaurs also appeared in the Late Triassic Period, around 200 million years ago. These dinosaurs had a pubis bone pointing down and backward. Ornithischians included many later kinds of plant eaters, including stegosaurs and horned dinosaurs.
Around 230 million years ago the first of the lizard-hipped plant eaters, called prosauropods, appeared. They grew up to 20 feet (6.5 meters long). Prosauropods had small heads and waled either on two legs or on all fours. Bird hipped plant eaters, such as Heterodontosaurus appeared at the same time. These first ornithischians were no bigger than turkeys.