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- Equidae Through the
Ages - Extant
Equids - Glossary - References
A brief history of the family Equidae
The family Equidae has a 55-million year history which
has been preserved in one of the most complete fossil records of
any animal group. Although over three dozen genera of this family have been described,
only one genus, Equus, with 6-8 extant species, has survived to the present day. Because
of this, the family Equidae has historically and popularly been held as a classic example
of orthogenesis, with a progressive trend toward larger size, fewer toes, and
sturdier teeth. This historical view is inaccurate, however, as the family tree of Equidae
is not a linear path with Equus at its end, but is complex and branching, and reflects
the changing environmental conditions throughout the Cenozoic era.
