evolution of the horse Essay -- essays papers

evolution of the horse ï » ¿For many people, the horse family remains the classic example of evolution. As more and more horse fossils have been found, some ideas about horse evolution have changed, but the horse family remains a good example of evolution. In fact, we now have enough fossils of enough species in enough genera to examine details of evolutionary change. Evolution does not occur in a straight line toward a goal, like a ladder; rather, evolution is like a branching bush, with no predetermined goal. Horse species were constantly branching off the evolutionary tree and evolving along various unrelated routes. There’s no discernable straight line of horse evolution. Many horse species were usually present at the same time, with various numbers of toes, and adapted to various diets. In other words, horse evolution had no inherent direction. We only have the impression of straight line evolution because only one genus happens to still be alive, which deceives some people into thinking that the one genus was somehow the target of all the evolution. Instead, that one genus is merely the last surviving branch of a once mighty and sprawling bush. 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, and increase in body size. But these trends are not seen in all of the horse lines. On the whole, horses got larger, bu...