(1) The vertical lines represent the actual time ranges of equid genera or clades.(2) It is the closest living relative of the domestic horse, and despite a difference in chromosome number, the two species are the only members of the equid family still capable of producing fertile offspring if interbred.(3) Hippidion was so distinctly different from other horses that it was considered to have diverged from the equid lineage about 10 million years ago.(4) The equid and mammoth remains came from the upper unit and the mastodon and edentate material came from the middle unit.(5) For example, a thoroughbred is a type of a horse, which is an equid , which is a mammal and so on.(6) Like all equids , mountain zebras are polygynous.(7) Domestic equids range worldwide; in the wild equids occur mainly in East Africa and the Near East to Mongolia.(8) Today only seven species of wild equids remain - three asses, three zebra and one wild horse - and the World Conservation Union now lists most of these as endangered.(9) Here I test whether this assumption holds true by analyzing the feeding strategy of various ungulates, particularly equids .(10) Notably, in the three mammalian groups, equids , murids, and peromyscids, in which placental development of interspecific hybrids was analyzed to date, placentation defects were observed.(11) The orbital region is important because it has been demonstrated as useful in classifying different species of equids .(12) This succession of early primitive types with later more advanced forms, and those with their still more advanced descendants, is not unlike the evolution of equids , titanotheres, and other fast-evolving taxa.(13) Bernor and Harris describe the three species of hipparionine equids found at Lothagam.
