Avialans facts for kids

Avialae is a special group of dinosaurs. This group includes all modern birds and their closest extinct relatives. It is a clade, which means it's a family tree of animals that share a common ancestor. Avialae contains the only living dinosaurs we know today: birds! It also includes other dinosaurs called coelurosaurs that are thought to be their ancestors.

There are two main ways scientists define what Avialae means.

What is Avialae?

Avialae is the scientific name for the group of dinosaurs that eventually became birds. It's like saying "the bird-dinosaur family." This group is very important because it shows how birds evolved from smaller, feathered dinosaurs.

Defining Avialae

Scientists use different ways to decide which animals belong to the Avialae group. These definitions help us understand the history of birds.

Based on Physical Traits

One way to define Avialae is by looking at the physical features of the animals. In 1986, a scientist named Jacques Gauthier described Avialae as:

• All dinosaurs that had feathered wings.
• These wings were used for flapping flight.
• It also includes all the birds that came from these flying dinosaurs.

So, if a dinosaur had feathered wings and could fly, or if it was a descendant of such a creature, it would be part of Avialae.

Based on the Family Tree

Another way to define Avialae is by looking at how closely related animals are to each other. This is called a "branch-based" definition because it looks at the branches of the dinosaur family tree.

• Many scientists define Avialae as: all theropod dinosaurs that are more closely related to modern birds than they are to a specific dinosaur called Deinonychus.

This means that if a dinosaur is on the "bird side" of the family tree, closer to birds than to Deinonychus, it belongs to the Avialae group. Deinonychus was a fierce, meat-eating dinosaur, but it was not as closely related to birds as the Avialae group.

See also

In Spanish: Avialae para niños