In the evolution of horse, following evolutionary changes occurred :

(1) Progressive Evolutionary Trends

(i) General increase in size and weight.

(ii) Lengthening of limbs.

(iii) Lengthening of middle toe in both fore limbs and hindlimbs.

(iv) Increase in height.

(v) Increase in neck length.

(vi) Enlargement and complexity of brain, specially cerebral hemispheres.

(vii) Lengthening of facial region of head.

(viii) Increase in the complexity of molar teeth.

(2) Progressive Evolutionary Trends

(i) Progressive loss of toes in both forelimbs and hindlimbs.

(ii) Progressive loss of canines in both upper and lower jaws.

(iii) Loss of hair from the body.