Mosasaur 3D scale pattern as hydrodynamic adaptation

[Jocelyn Falconnet <j.falconnet@gmail.com>]

Lindgren J., Everhart M.J. & Caldwell M.W. 2011. Three-dimensionally 
preserved integument reveals hydrodynamic adaptations in the extinct 
marine lizard Ectenosaurus (Reptilia, Mosasauridae). PLoS ONE 6(11): e27343.
doi:10.1371/journal.pone.0027343

The physical properties of water and the environment it presents to its 
inhabitants provide stringent constraints and selection pressures 
affecting aquatic adaptation and evolution. Mosasaurs (a group of 
secondarily aquatic reptiles that occupied a broad array of predatory 
niches in the Cretaceous marine ecosystems about 98–65 million years 
ago) have traditionally been considered as anguilliform locomotors 
capable only of generating short bursts of speed during brief ambush 
pursuits. Here we report on an exceptionally preserved, long-snouted 
mosasaur (Ectenosaurus clidastoides) from the Santonian (Upper 
Cretaceous) part of the Smoky Hill Chalk Member of the Niobrara 
Formation in western Kansas, USA, that contains phosphatized remains of 
the integument displaying both depth and structure. The small, ovoid 
neck and/or anterior trunk scales exhibit a longitudinal central keel, 
and are obliquely arrayed into an alternating pattern where neighboring 
scales overlap one another. Supportive sculpturing in the form of two 
parallel, longitudinal ridges on the inner scale surface and a complex 
system of multiple, superimposed layers of straight, cross-woven helical 
fiber bundles in the underlying dermis, may have served to minimize 
surface deformation and frictional drag during locomotion. Additional 
parallel fiber bundles oriented at acute angles to the long axis of the 
animal presumably provided stiffness in the lateral plane. These 
features suggest that the anterior torso of Ectenosaurus was held 
somewhat rigid during swimming, thereby limiting propulsive movements to 
the posterior body and tail.

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"As a Professor of Science, I assure you we did in fact evolve from 
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