Doin’ the “Pterosaur Walk”

A man acting like a pterosaur on the beach

Figure 1. Man acting like a pterosaur on the beach with ski poles (click for blogspot). Note the vertical backbone and ski poles contributing to stability, not thrust. His mate (or daughter) is walking bipedally.

Footprints from around the world tell us that pterosaurs of all sizes walked on prehistoric beaches. Today we have two competing configurations hypothesizing how pterosaurs did this. I like the configuration demonstrated above (Fig. 1) and it is supported by matching tracks to trackmakers, following the thrust vectors and considering methods by which pterosaurs might launch themselves into the air.

The traditional and majority view (Bennett 1997, Fig. 2) posits that the backbone was nearly horizontal and the fingers impressed the sediment far ahead of the shoulders (Fig. 1). This has been criticized here and here on several grounds.

Walking pterosaur according to Bennett

Figure 1. Click to animate. Walking pterosaur according to Bennett 1997. Note the forelimbs provide no forward thrust, but merely act as props.

The heretical minority opinion posits that the backbone was held much more vertically (diagonally) such that the toes impressed beneath the center of balance while standing, slightly behind while walking (as in humans, Fig. 2) and that the fingers impressed much closer to the center of balance – when they could (in Pteranodon, for instance, they could not).

Pterodactylus walk matched to tracks according to Peters

Figure 2. Click to animate. Plantigrade and quadrupedal Pterodactylus walk matched to tracks. Note the more vertical backbone and the forelimbs not contributing thrust to locomotion, only stability.

Otherwise the fingers did NOT contribute thrust to forward progression while walking. In this pose pterosaurs could merely lift their ski-pole like arms to launch themselves bipedally. Such a pose also follows from bipedal ancestry and a secondary acquisition of a quadrupedal pose as demonstrated, among other traits, by a backward-pointing finger #3.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Bennett SC1997. Terrestrial locomotion of pterosaurs: a reconstruction based on Pteraichnus trackways. Journal of Vertebrate Paleontology, 17: 104–113.

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