The Evolution of Dinosaurs

During the Triassic period, a large number of different dinosaurs started to appear. This was a time between 243 and 233.23 million years ago, and the evolution of these reptiles has been studied to this day. The study of dinosaur evolution is still ongoing and active research is carried out today.

Theropod dinosaurs

During the Late Jurassic Period, theropod dinosaurs were the dominant terrestrial carnivores. Theropods ranged in size from crow-sized Microraptor to colossal Tyrannosaurus rex.

While most theropods were carnivores, some were herbivores. Many theropods have feathers, and they may have used feathers to regulate their body temperature.

A feather can be found in fossilized bones. Feathers are not very common in the fossil record, but there are examples. Some dinosaur skeletons have imprints of feathers. These imprints can be used to assign a related dinosaur to a particular species.

Some of theropods, such as Archaeopteryx, were able to fly like modern birds. They also had feathers, but these feathers were less likely to be preserved in the fossil record.

Theropods were one of the most diverse groups of saurischian dinosaurs. They had a variety of diets, some of which included eggs and insects.

Saurischians

During the mid-Triassic Period, dinosaurs were the dominant land animals on earth. These creatures were bipedal, carnivorous, and had sharp teeth. They lived in a tropical climate. There were a variety of dinosaurs, but the saurischians and ornithischians were the two main groups.

Saurischian dinosaurs are lizard-hipped dinosaurs. These dinosaurs evolved in a variety of ways. They were bipedal, had a lizard-like pelvis, and a three-pronged pelvic structure. The pubis was rotated to a forward position along the anterior side of the pelvis.

Saurischian dinosaurs were part of a larger subgroup called Maniraptora. Other subgroups include archosaurians, which include crocodiles and birds. In addition to being carnivorous, some saurischians also ate plants.

Some scientists believe that modern birds are the descendants of coelurosaurs. This group also evolved from lizard-hipped theropods.

Ornithischians

Several kinds of ornithikians were among the early Jurassic period's many dinosaur species. These were smaller and more herbivorous than saurischians, but were still dinosaurs. They had a leaf-shaped, toothless horny beak and an efficient grinding surface in their upper and lower jaws. In some lineages, there were dozens of close-set teeth.

Ornithikians were also the first terrestrial vertebrate group to be dominated by plants. Several types of ornithischians, like squamates and ankylosaurs, were more similar to dinosaurs than saurischians, though the two groups were not entirely separate evolutionary lineages. Ornithikians had a number of advanced skeletal features, including a pelvis, a lattice of bony tendons, and an unusually large, leaf-shaped, toothless horny jaw. Among the most notable were the duckbills, which had large, hollow crests on top of their skulls. Some scientists believe these crests were used for mating rituals.

Tyrannosaurus Rex

During the Late Cretaceous, Tyrannosaurus rex was an active predator. Using its large, powerful jaws and two strong legs, T. rex stomped across its territory.

Tyrannosaurus rex was a large, powerful, theropod dinosaur that lived in western North America. Tyrannosaurus lived on the continent of Laramidia, which was part of an island continent that split North America into western and eastern halves.

Although most tyrannosaurines have been found from the end of the Cretaceous, some basal forms are known from the Early Cretaceous. The Tyrannosaurus rex skull is the longest known, at 1.3 metres long.

Tyrannosaurus rex weighed up to eight tons. Although it was a large dinosaur, it was still relatively slow. It would have had to hunt very large prey.

Tyrannosaurus rex also had very large skull bones. These bones are several centimetres thick. They are strongly braced.

Dino-chicken

Taking a page from the animal kingdom book, scientists have tinkered with the feathers of the domestic fowl to produce a small carnivore of the past. A cock is the adult male bird. For the most part, it is a plain Jane. The researchers have a few tricks up their sleeves.

The first and most impressive was the fact that the researchers were able to show that there were some genes associated with the tail's development. They also made a digital model of the skull using a CT scanner. The biggest challenge was finding the right genes to target. It took seven years to see results. The good news is, the researchers are in it for the long haul. The end result is an improved breed of domestic fowl with some of the most interesting dinosaur like characteristics.