Hierarchy classification:

1. top of the aat hierarchies
2. Agents Facet
3. Living Organisms (hierarchy name)
4. living organisms (entities)
5. Eukaryota (domain)
6. Animalia (kingdom)
7. Chordata (phylum)
8. Vertebrata (subphylum)
9. Aves (class)

Anotations

Scope note:

Extinct subclass of birds having teeth in both jaws, a long, feathered tail, by being less specialized for flight than modern birds, a body elongated and reptilelike, forelimbs with three clawed digits, a small brain and eyes, and bones that are not filled with air (nonpneumatic).