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Pterosaur morphological evolution

From: Ben Creisler

A new online paper:

Katherine C. Prentice, Marcello Ruta & Michael J. Benton (2011)
Evolution of morphological disparity in pterosaurs.
Journal of Systematic Palaeontology (advance online publication)

Pterosaurs were important flying vertebrates for most of the Mesozoic, from
the Late Triassic to the end of the Cretaceous (225--65 Ma). They varied
enormously through time in overall size (with wing spans from about 250 mm
to about 12 m), and in features of their cranial and postcranial skeletons.
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. Pterodactyloid disparity
shifted through time, with different, small portions of morphospace
occupied in the Late Jurassic and Late Cretaceous, and a much larger
portion in the Early Cretaceous. This explosion in disparity after 100 Ma
of evolution is matched by the highest diversity of the clade: evidently,
pterosaurs express a rather 'top heavy' clade shape, and this is reflected
in delayed morphological evolution, again an unexpected finding. The
expansion of disparity among pterodactyloids was comparable across
subclades: pairwise comparisons among the four pterodactyloid superfamilies
show that, for the most part, these clades display significant
morphological separation, except in the case of Dsungaripteroidea and
Azhdarchoidea. Finally, there is no evidence that rhamphorhynchoids as a
whole were outcompeted by pterodactyloids, or that pterosaurs were driven
to extinction by the rise of birds.

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