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Ichthyosaurs and mosasaurs had dark skin pigments

From: Ben Creisler

A new online paper (the supp. material is free):

Johan Lindgren, Peter Sjövall, Ryan M. Carney, Per Uvdal, Johan A.
Gren, Gareth Dyke,  Bo Pagh Schultz, Matthew D. Shawkey, Kenneth R.
Barnes & Michael J. Polcyn (2014)
Skin pigmentation provides evidence of convergent melanism in extinct
marine reptiles.
Nature (advance online publication)

Throughout the animal kingdom, adaptive colouration serves critical
functions ranging from inconspicuous camouflage to ostentatious sexual
display, and can provide important information about the environment
and biology of a particular organism. The most ubiquitous and abundant
pigment, melanin, also has a diverse range of non-visual roles,
including thermoregulation in ectotherms. However, little is known
about the functional evolution of this important biochrome through
deep time, owing to our limited ability to unambiguously identify
traces of it in the fossil record. Here we present direct chemical
evidence of pigmentation in fossilized skin, from three distantly
related marine reptiles: a leatherback turtle, a mosasaur and an
ichthyosaur. We demonstrate that dark traces of soft tissue in these
fossils are dominated by molecularly preserved eumelanin, in intimate
association with fossilized melanosomes. In addition, we suggest that
contrary to the countershading of many pelagic animals, at least some
ichthyosaurs were uniformly dark-coloured in life. Our analyses expand
current knowledge of pigmentation in fossil integument beyond that of
feathers, allowing for the reconstruction of colour over much greater
ranges of extinct taxa and anatomy. In turn, our results provide
evidence of convergent melanism in three disparate lineages of
secondarily aquatic tetrapods. Based on extant marine analogues, we
propose that the benefits of thermoregulation and/or crypsis are
likely to have contributed to this melanisation, with the former
having implications for the ability of each group to exploit cold

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