What change occurred in the shape of the horse from Hyracotherium to Equus?

Tracing a line of descent from Hyracotherium to Equus reveals several apparent trends: reduction of toe number, increase in size of cheek teeth, lengthening of the face, increase in body size. But these trends are not seen in all of the horse lines.

Explanation:

a warm, wet climate will produce the highest rate of weathering. the warmer a climate is, the more types of vegetation it will have and the greater the rate of biological weathering (figure below). this happens because plants and bacteria grow and multiply faster in warmer temperatures.