![Picture](/uploads/2/3/9/3/23932527/5822656.jpg)
Dinosaurs weren't the first reptiles to rule the earth.
The first dinosaurs evolved in the middle to late Triassic period, about 230 million years ago. Before then, the dominant land reptiles were archosuars (ruling lizards) and therapsids
(mammal-like reptiles), and for 20 million or so years after the first
dinosaurs appeared the most reptiles were crocodiles. It was only at the
beginning of the Jurassic period, about 200 million years ago, that dinosaurs began their rise i dominance.
The first dinosaurs evolved in the middle to late Triassic period, about 230 million years ago. Before then, the dominant land reptiles were archosuars (ruling lizards) and therapsids
(mammal-like reptiles), and for 20 million or so years after the first
dinosaurs appeared the most reptiles were crocodiles. It was only at the
beginning of the Jurassic period, about 200 million years ago, that dinosaurs began their rise i dominance.
![Picture](/uploads/2/3/9/3/23932527/3394360.gif)
Most dinosaurs were vegetarians.
Giant predators like the T- Rex and Giganotosaurus get all the press, but it's a fact of nature that the meat-eating predators of any given ecosystem are tiny in number compared to the plant-eating animals they prey on. By analogy with modern habitats in Africa and Asia, herbivorous hadrosaurs, ornithopods and (to a lesser extent) sauropods probably roamed the Mesozoic Era in crowded herds, and were hunted by sparser packs of large, small and medium-sized theropods.
Giant predators like the T- Rex and Giganotosaurus get all the press, but it's a fact of nature that the meat-eating predators of any given ecosystem are tiny in number compared to the plant-eating animals they prey on. By analogy with modern habitats in Africa and Asia, herbivorous hadrosaurs, ornithopods and (to a lesser extent) sauropods probably roamed the Mesozoic Era in crowded herds, and were hunted by sparser packs of large, small and medium-sized theropods.
![Picture](/uploads/2/3/9/3/23932527/6828194.jpg)
The dinosaur kingdom is split into two main groups.
At first I thought it would be easier to divide dinosaurs into herbivores and carnivores,but paleontologists see things differently. Distinguishing between saurischaun ("lizard-hipped") and orithischian ("bird-hipped"dinosaurs. Saurischian dinosaurs include carnivorous theropods and herbivorous sauropods, while ornithischians account for the remainder of plant eaters, including hadrosaurs, ornithopods and ceratopsians, among others. Oddly enough, birds evolved from "lizard-hipped," rather than "bird-hipped," dinosaurs!
At first I thought it would be easier to divide dinosaurs into herbivores and carnivores,but paleontologists see things differently. Distinguishing between saurischaun ("lizard-hipped") and orithischian ("bird-hipped"dinosaurs. Saurischian dinosaurs include carnivorous theropods and herbivorous sauropods, while ornithischians account for the remainder of plant eaters, including hadrosaurs, ornithopods and ceratopsians, among others. Oddly enough, birds evolved from "lizard-hipped," rather than "bird-hipped," dinosaurs!