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. Mammalia (class)
10. Perissodactyla (order)
11. Equidae (family)

Anotations

Scope note:

Genus of small dog-sized animals representing the oldest known horse; they lived in the Eocene Epoch. Characterized by a relatively short face, eye sockets nearer the middle than modern horses, and a short space between the front teeth and the cheek teeth (diastema).