Archaeopteryx is considered one of the earliest known birds that evolved from avian dinosaurs, which were a subgroup of flying dinosaurs. While Archaeopteryx had the ability to fly, it also had many non-avian dinosaur characteristics like teeth and a long bony tail, showing that it was still transitioning from dinosaur to modern bird.

1. Early birds such as Archaeopteryx are considered avian dinosaurs.
Avian dinosaurs are a subgroup of dinosaurs that evolved the ability to
fly, and Archaeopteryx is considered one of the earliest known birds.
However, it is important to note that Archaeopteryx also had many
characteristics that were characteristic of non-avian dinosaurs, such as
teeth and a long bony tail.