Tooth Reduction

 

One of the main evolutionary trends in pterosaurs is the reduction of teeth.  Clearly, where teeth are not essentially required for feeding, a reduction in teeth numbers would be a weight saving factor, giving some pterosaurs a survival advantage.

The first noticeable reduction in teeth came with some of the species that only retained teeth at the end of the jaw.


Cycnorhamphus suevicus

It seems likely that any pterosaur that had teeth in the anterior jaw only, would need cheek pouches to stop food falling out of its mouth.  There is no evidence for this in the fossil record.

 


 


Pterosaurs like Tapejara show a complete loss of teeth.  There is also a significant reduction in the length of the jaw in this type of pterosaur.

The function of the bony crest is unclear, but it is likely to serve as a jaw strengthening structure and possibly a display crest.  If Tapejara was a water feeder, then this may also be an aqua-dynamic stabilising structure.

Examples of complete tooth reductions can be seen in the jaws of the giant pterosaurs; Nyctosaurus, Pteranodon and Azhdarcho, where the smooth beak like jaws have no teeth at all.

Eaton G. F., 1903, The characters of Pteranodon. American Journal of Science. 16, 82–86 and pls 6–7.

von Fraas O., 1878, Über Pterodactylus suevicus, Qu., von Nusplingen. Paläontographica 25, 163–174 and pl. 22

Marsh O. C., 1884, Principal characters of American Cretaceous Pterodactyls. Part 1. The skull of Pteranodon. Am. J. Sci. (3) 27, 423–426.

Wellnhofer P. and Kellner A. W. A., 1991, The skull of Tapejara wellnhoferi Kellner (Reptilia: Pterosauria) from the Lower Cretaceous Santana Formation of the Araripe Basin, Northeastern Brazil. Mitt. bayer. Staatsslg Paläont. hist. Geol.31, 89–106.

Witton M. P., 2010, Pteranodon and beyond: the history of giant pterosaurs from 1870 onwards, Geological Society, London, Special Publications, vol 343; pages 313-323

 

01 - Background

02 - Tricuspid teeth

03 - early Monocuspid teeth

04 - late Monocuspid teeth

05 - Tooth reduction

06 - Special adaptations

07 - Key to identification

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