The earliest zebra may have been the fine-grained zebra, which evolved from the original horse four million years ago. Fossils of prehistoric horses are found at the Kevin Culture Stone Bed National Museum in Kevin, Idaho, USA. Its body is roughly the same as zebras, its skeleton is short and narrow like donkeys, and its figure is more like fine-striped zebras.
There are currently three species and subspecies of zebras. The number of zebras varies greatly, and the relationship between taxonomic status of several subspecies is well known. The most common species are plain zebras (Equus quagga), also known as common zebras, mostly living in South Africa and East Africa. There are six identified subspecies: E. Q. burchellii, E. Q. chapmani, E. Q. crawshayi, E. Q. borensis, E. Q. boehmi and extinct quagga. ) Equus zebra of South Africa has smooth skin, white abdomen and narrow markings. It has two subspecies, but belongs to endangered animals. Equus grevyi is the largest zebra. They are small, a bit like donkeys. Its zebras inhabit semi-arid grasslands in Ethiopia and Northern Kenya. Zebras are also the least numerous zebras, and are nearly endangered.
Distributions of different zebras may overlap, but they never cross, such as the Che subspecies of white zebras and plain zebras.
In captivity, zebras are likely to cross, such as plain zebras and mountain zebra clubs, and their hybrids look similar to plain zebras except for their larger ears and some differences. If a male zebra crosses with a female zebra, their chances of miscarriage are high.