The given diagram highlights the major changes during the horse's 40-million-year evolution.
Overall, the horse's evolution is marked by significant changes in foot bone structure and the size of this species, step-by-step transforming a small mammal into the modern horse.
The Eohippus living 40 million years ago bears a characteristic of a 4-toe foot bone. The number of toes is reduced by one during the next 10-million-year evolution, forming a 3-toe foot bone with the middle toe growing in terms of size which characterizes the Mesohippus. The Merychippus, the third species of the horse's evolution, has a middle toe continuing to significantly evolve, almost double in size compared with other toes. The last 15-million-year evolution witnesses a radical change in the horse's foot bone structure when the 3-toe foot completely transforms into the hoof.
This evolution also witnesses a significant increase in the size of the horse. In tandem, only Eohippus and Mesohippus bear the characteristic of the C-shaped backbone while Merychippus is characterized by the almost-flat backbone, resembling that of the modern horse. The 40-million-year evolution also witnesses the noticeable growth of mane and tail, which distinguishes the modern horse from its mammal ancestor, Eohippus.
The
given
diagram highlights the major
changes
during the
horse's
40-million-year evolution.
Overall
, the
horse's
evolution
is marked
by significant
changes
in foot
bone
structure and the
size
of this species, step-by-step transforming a
small
mammal into the modern horse.
The
Eohippus
living 40 million years ago bears a characteristic of a 4-toe foot
bone
. The number of toes is
reduced
by one during the
next
10-million-year
evolution
, forming a 3-toe foot
bone
with the middle toe growing in terms of
size
which characterizes the
Mesohippus
.
The
Merychippus
, the third species of the
horse's
evolution
, has a middle toe continuing to
significantly
evolve, almost double in
size
compared with other toes.
The
last 15-million-year
evolution
witnesses a radical
change
in the
horse's
foot
bone
structure when the 3-toe foot completely transforms into the hoof.
This
evolution
also
witnesses a significant increase in the
size
of the horse. In tandem,
only
Eohippus
and
Mesohippus
bear the characteristic of the C-shaped backbone while
Merychippus
is characterized
by the almost-flat backbone, resembling that of the modern horse. The 40-million-year
evolution
also
witnesses the noticeable growth of mane and tail, which distinguishes the modern horse from its mammal ancestor,
Eohippus
.