Morphological Disparity in Pterosaurs? Not So Much.

A recent paper on morphological disparity in pterosaurs (Prentice et al. 2011) claimed: “Comparisons of disparity based on discrete cladistic characters show that the basal paraphyletic rhamphorhynchoids (Triassic–Early Cretaceous) occupied a distinct, and relatively small, region of morphospace compared to the derived pterodactyloids (Late Jurassic–Late Cretaceous). This separation is unexpected, especially in view of common constraints on anatomy caused by the requirements of flight.

Obviously a lot of work here, but it hinged on one mistake. Prentice et al. (2011) based their findings on the old “rhamphorhynchoid” / “pterodactyloid” dichotomy. A new, more inclusive tree shows this dichotomy is false. The first dichotomy is actually Dimorphodontia/Eudimorphodontia and there were four “pterodactyloid”-grade clades. Based on the new tree the various morphospaces  actually overlap quite a bit.

Pterosaur morphospace

Figure 1. Click to enlarge. A. Distinct morphospace based on outmoded rhamphorhynchoid/pterodactyloid dichotomy. Other morphospaces defined by new family tree.

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:
Prentice KC, Ruta M and Benton MJ 2011. Evolution of morphological disparity in pterosaurs, Journal of Systematic Palaeontology, DOI:10.1080/14772019.2011.565081

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