Equidae
Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus "Equus". Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
Ibyka
Ibyka is an extinct genus of Iridopteridales, and a possible ancestor to horsetails. 
The probable relationships within Equisetopsida are shown in the cladogram below. The position where "Ibyka" would be has been added.