Theropoda

Theropoda is one of the three major groups of **dinosaur**s, along with Ornithischia and Sauropodomorpha. Theropods have special hollow bones and three toes with claws on each foot. They are part of the saurischian dinosaurs, meaning they are more closely related to sauropods than to ornithischians. Most theropods ate meat, but some later groups also ate plants or both.

Many theropods had feathers, especially a group called Coelurosauria. It’s possible that feathers were in other theropods too. An amazing fact is that birds evolved from small theropods during the Jurassic period. Today, there are many kinds of birds, making theropods the only kind of dinosaur still alive today.

Theropods first appeared about 231 million years ago during the Late Triassic period. They were the main meat-eating animals on land from the Early Jurassic to the end of the Cretaceous period, about 66 million years ago. Some of the biggest meat-eaters ever, like Tyrannosaurus and Giganotosaurus, were theropods. There were also very small theropods, like some scansoriopterygids, about the size of small birds today.

Biology

Theropods were a group of dinosaurs with hollow bones and three-toed limbs. They came in many sizes, diets, and looks. Some were big hunters, while others were small and might have eaten plants, insects, or both.

Theropods ate different things, like meat, plants, or both. Their teeth changed to match what they ate. Some had sharp teeth for catching animals, and others had flatter teeth for eating plants. Over time, theropods grew features like feathers. Today, birds are their descendants.

Evolutionary history

In the late Triassic period, early theropod dinosaurs lived and changed over time. The first theropods were simple dinosaurs that ate meat, like Eodromaeus and maybe the herrerasaurids from Argentina. These early dinosaurs had some older features and some new ones.

Later, clearer theropods appeared, such as the Coelophysoidea, small and light hunters like Coelophysis. These animals lived from the late Triassic into the early Jurassic period. An important group that lived into the Jurassic period was Neotheropoda. This group includes most later theropods and leads to modern birds. Another group, Averostra, includes famous theropods like Ceratosaurus and the Tetanurae, which are closer to birds. During the Jurassic and Cretaceous periods, many different types of theropods lived, including the powerful Tyrannosaurus and fast Velociraptor. Some of these theropods eventually evolved into the birds we know today.

Classification

O. C. Marsh named Theropoda in 1881, which means "beast feet." He used the name for meat-eating dinosaurs, and later included more types.

Today, Theropoda includes many groups of meat-eating dinosaurs and their descendants. Important groups are Coelophysoidea, Ceratosauria, Tetanurae, and Coelurosauria. Well-known theropods include Allosaurus, Tyrannosaurus, and birds, which came from theropods.