Mark’s approach however was not to produce a single transitional form but several of them. He worked his way through something very close to an archosaur so something nearly a pterosaur over three distinct stages. That gives a much more thorough take on this issue and allows him to explore not just what these things may have looked like, but also the evolutionary pressures and problems at different stages of their evolution. What’s interesting for me is that it also contrasts and compliments with something that I’ve been working on.
Most of you are probably aware that some years ago a major academic book was promised on the pterosaurs. The damn thing seems to be on near-permanent hiatus (I wrote my chapters back in 2008) but as part of the introduction I did on pterosaur origins I got together with Luis Rey and produced an updated ‘protopterosaur’ to take into account both the ornithodires, but also new data and hypotheses on wing evolution, basal pterosaurs and other issues. Luis has been kind enough to let me put up his effort and Mark has also passed on one of his intermediates for comparison (obviously these are copyright to these respective artists).
|Marks' version of Rupert Wild's 'protopterosaur' (left) and his own suggested animal (right)|
For completeness and as a general guide, here’s the figure caption I produced for Luis’ art. I would have normally gone for a darker colour and less bright pattern to emphasise this as a small animal, vulnerable to predators, but when you ask Luis to illustrate and animal “not bold colours” should never be in your description. Still, the other bits of anatomy I wanted and the details are all in there and reflect various issues of pterosaur origins:
|Luis Rey's version|