One of the oldest pieces of evidence supporting the theory of evolution is the fossil record. Fossils are the ancient bones (or other evidence) from life that are preserved in rock. The fossil record provides an astounding array of evidence that supports the theory of evolution. Through the study of fossils, an overwhelming body of evidence has accumulated depicting the progress of lifeforms on earth.
Because it is a bit much to tackle in one short essay, I’ll narrow my focus. I remember a neat exhibit I saw about eight years ago at a small museum in northern Nebraska. It is at the site of the Ashfall Fossil beds.
In the main lobby of this museum they have a display case showing foot bones from a variety of horse-like animals. Over the years there have been many many different kinds of horses. The modern horse (of genus equus) is the last from a diverse family ultimately descended from a common three-toed ancestors. Over time there has many different horse-like animals in wide variety of forms. All but one of the 27 genera that have existed are now extinct. That fact alone shows the creative but ruthless nature of evolution — that so many would come to exist, ultimately to dissappear and be replaced by another species.
One interesting thing about the ancestral species of horses is how their feet transformed from a three-toed structure into the modern horse’s hoof. These two forms are very different. It is hard to imagine how the one could gradually transform into the other. But evolution works on the principle of gradual change, with no intermediate form having a detrimental effect on the organism.
At first glance, this may seem to be a valid argument against evolution. Consider a more extreme, fictitious example: Why do you suppose that no animals have evolved jet engines? I believe it is because a jet engine is exceedingly complex. But not only that. Also because there is no conceivable benefit gained by most of a jet engine. A jet engine either works or else it doesn’t — and building 90% of a jet engine is an enormous burden on a struggling species. Thus you can’t invent a scenerio where gradual evolutionary pressure would result in a jet engine.
Contrast that with how animals do fly — by flapping wings. This process has some advantage even when the flight is limited. For example, the flying squirrel has relatively little adaptation (just a slightly modified rib cage and extra skin webbing their arms and legs) — and yet this enables the animal to move around a jungle better than a regular squirrel can. Given enough time and selective pressure, the flying squirrel might eventually evolve into an animal as adept at flying as a bat.
So how does the horse fit into this? The fossils from the Ashfall fossil beds show a variety of species of horses. The feet of those horses are structured from the same bones as both modern horses and the ancient three-toed ancestor. But they range in structure from very modern to very ancient in appearance. And the key point is — now that we can see them — it’s clear that all of them worked just fine.
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