Wednesday 29 July 2015

I Love Transition Fossils

One of the many stupid arguments put forward by people trying to dispute the theory of evolution by natural selection is: if evolution is true then there should be fossils of missing links, if birds evolved from dinosaurs then show me a fossil that is half bird and half dinosaur. Now, asides from the fact that this shows a gross misunderstanding of the theory there are actually a great deal of 'missing links' out there; they're called transition fossils and there is now a quite beautiful catalogue of them. We have transition fossils for pretty much every major order of animals out there, the only exception I can think of is bats, we don't yet have a decent fossil record of their evolution - it's only a matter of time, though.

We have ambulocetus, a wonderful cetacean (whale and dolphin) precursor that could swim well and walk around on land too; we have tiktaalik, a transition fossil of a fish that had 4 primitive legs and was well on its way to being an amphibian; and we have the legendary archaeopteryx, which is quite literally half bird half dinosaur. The fossil record, by its very nature, will never be 100% complete, but it is now well stocked with a plethora of transition fossils all of which add support to the now invincible edifice that is evolution by natural selection, and, I'm pleased to say we can now welcome another strut to the structure.

tetrapodophis snake, transition fossil, evolution, science
Image used with permission

An article in Nature has given details of an awesome new transition fossil; it is quite clearly a snake but equally clearly it has four little legs. The legs would not have allowed it to walk, they're too small and it's body is too long, but they may have allowed it to grab prey a little easier or get a better grip when mating hence its name: Tetrapodophis amplectus which translates as four-legged hugging snake.

For a long time it was uncertain if snakes had evolved from land animals or aquatic animals. If the latter then we would expect to see a transition fossil with a tail adapted for swimming and vestigial fins; if the former then we would expect, well, we would expect exactly what this fossil shows. Another little gap in our knowledge has been filled in, leaving one less place for evolution deniers to hide.

No comments:

Post a Comment