250 Million Years Ago
The period when the first dinosaurs appeared was called the “Triassic Period.” At that time, the Earth was much different than it is today.
During the Triassic Period, the climate was very hot and dry. Mammal-like Reptiles dominated the land and some of them grew to lengths of almost 20 feet. Twenty foot monsters ruled the land. This was the time when dinosaurs evolved, according to the theory of evolution.
The first dinosaur, sometimes called the “dawn dinosaur,” was Eoraptor. It was about the size of a dog. An almost complete skeleton was found in Argentina in 1993. Scientists were delighted. The discovery of an almost complete skeleton of a dinosaur is a very rare find.
Reptiles as the most dominant creatures on the planet. While not all of the Mammal-like reptiles vanished, they became vulnerable to the emerging dinosaurs. Many scientists believe that as the dinosaurs got bigger, faster and more ferocious, they killed most of the Mammal-like reptiles, and those that survived were the smallest of these creatures. Eventually, the only ones left were the very smallest and these evolved into early mouse-sized mammals.
begin to grow and diversify. The plant-eating dinosaurs, which appeared during
the mid-to-late Triassic more than 200 million years ago, were the first Ornithischians, or bird-hipped dinosaurs, and were no bigger than turkeys. Huge
ferns and other primitive non-flowering trees dominated the land. Grass never
grew during the Triassic and the dinosaurs got bigger and bigger as a result of
having little competition from any other forms of life on the land. One of the
most significant developments to occur during the latter part of the Triassic
was that some creatures took to the air. Two families of animals began to
develop at this time - flying reptiles, or Pterosaurs, and the first members of
the family that became birds.