Horse
The horse adapted to survive in areas of wide-open terrain with sparse vegetation, surviving in an ecosystem where other large grazing animals, especially ruminants, could not. Horses and other equids are odd-toed ungulates of the order Perissodactyla, a group of mammals that was dominant during the Tertiary period. In the past, this order contained 14 families, but only three—Equidae (the horse and related species), Tapiridae (the tapir), and Rhinocerotidae (the rhinoceroses)—have survived to the present day.
Erica
A number of increasingly detailed phylogenetic hypotheses for "Erica" have been published based on nuclear ribosomal and plastid DNA sequences. The closest relatives of "Erica" are "Daboecia" (one or two species) and "Calluna" (monospecific), representing the oldest surviving lineages of a, by inference, ancestrally Palearctic tribe Ericeae. The small number of European "Erica" species represent the oldest lineages of the genus, within which a single, order-of-magnitude more species-rich, African clade is nested. Within the African clade, Cape and Madagascan/Mascarene species respectively represent monophyletic groups.