CLAW MORPHOLOGY OF PTERANODON AND POSSIBLE AQUATIC LOCOMOTION

Previous studies (Bennett 2001, Bramwell and Whitfield 1974) have mentioned in passing that Pteranodon may have been able to swimming on the surface of the epicontinental seaway that covered the Western Interior of North America during the Cretaceous. Quantitative morphometrics were employed to examine Pteranodon claw morphology to ascertain how the morphology of the genus relates morphometrically to the claws found on the feet of aquatic birds and crocodylians, which served as extant phylogenetic bracketing taxa for pterosaurs. The taxa analyzed included four species of swimming birds, one wading bird, one terrestrial/perching bird, two species of crocodile, and one species of alligator, along with one (possibly two) species of Pteranodon.

Homologous landmarks were placed on digital photographs of avian, crocodylian, and pteranodont claws, and once these landmarks were transformed into Bookstein coordinates, morphometric data including distances between the landmarks, angles between the landmarks, aspect ratios of the claws, and curvature equations were derived for all of the specimens. These data were analyzed through the use of the program SYSTAT to determine principal component variables, which were then used to perform cluster analyses of digits one through four separately, as well as a cluster analysis of all digits together. Excel was then used to run ANOVA tests on all clusters in search of statistical differences at á = 0.05.

Preliminary results indicate that the claws of Pteranodon most closely resemble that of the Scarlet Ibis (similarities found in claw numbers one, three, and four) and of the seagull (similarities found in claw numbers two and four). In contrast, all four pteranodont claws are statistically different from all peacock, Great Auk, and Crocodylus porosus claws, indicating a significant dissimilarity between the claw morphology of Pteranodon and these taxa.

WORKS CITED

Bennett, S. C. 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part II. Size and Functional Morphology. Palaeontogr. Abt. A 260, 113-153

Bramwell, C. D. and Whitfield, G. R. 1974. Biomechanics of Pteranodon. Philadelphia Royal Transactions of the Society of London, (B), 267: 503–581.