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.
Equisetales
In the molecular phylogenetic classification of Smith et al. in 2006, Equisetales, in its present circumscription, was held to be the sole member of class Equisetopsida. The linear sequence of Christenhusz et al. (2011), intended for compatibility with the classification of Chase and Reveal (2009) which placed all land plants in Equisetopsida, made it the sole member of subclass Equisetidae, equivalent to Smith's Equisetopsida. The placement of Equisetales in subclass Equisetidae has subsequently been followed in the classifications of Christenhusz and Chase (2014) and PPG I (2016).