Equus (genus)
Equus is a genus of mammals in the family Equidae, which includes horses, donkeys, and zebras. Within Equidae, "Equus" is the only recognized extant genus, comprising seven living species. The term equine refers to any member of this genus, including horses. Like Equidae more broadly, "Equus" has numerous extinct species known only from fossils. The genus most likely originated in North America and spread quickly to the Old World. Equines are odd-toed ungulates with slender legs, long heads, relatively long necks, manes (erect in most subspecies), and long tails. All species are herbivorous, and mostly grazers, with simpler digestive systems than ruminants, but able to subsist on lower-quality vegetation.
Canadia (annelid)
There has been some debate as to the placement of "Canadia" within the Annelida phylum. Although it is commonly accepted to be within Annelida, it is uncertain how it relates to modern annelids. Most paleontologists agree that it belongs to the class Polychaeta due in part to the presence of Parapodium. It has been proposed to be a member of the order Phyllodocida along with "Wiwaxia", another organism from the Burgess Shale. Both were placed in a new superfamily called Canadiacea, and were thought to be of closer relationship to each other than to modern annelids. However, "Wiwaxia" is no longer believed to have been an annelid and there is currently dispute as to whether or not "Canadia" should be classified as belonging to anything more derived than Polychaeta.