Some of the largest beasts in the ancient seas had black skin or scales, new research finds.
Ancient leatherback turtles, toothy predators called mosasaurs and dolphinlike reptiles called ichthyosaurs all had black pigmentation, researchers report in this week's issue of the journal Nature. The findings come from an analysis of preserved skin from each of these creatures.
The animals' blackness likely helped them in a variety of ways, said study researcher Johan Lindgren, a mosasaur expert at Lund University in Sweden. "We suggest … that they used it not only as camouflage and UV protection, but also to be able to regulate their body temperature," Lindgren told LiveScience.
The study isn't the first to delve into the color of ancient creatures. For example, paleontologists have found that Microraptor, a small winged dinosaur from 130 million years ago, had black, crowlike feathers. The colors of marine animals are relatively uncharted territory, however.
Some fossils of extinct sea monsters have been found with black "halos" around the bones, suggesting remnants of skin. Anatomical analysis suggested these remnants were, in fact, melanosomes, the tiny packets of pigments that give skin, feathers and hair their color. Melanosomes contain melanin, a dark brown or black pigment.
Lindgren and his colleagues conducted a microscopic analysis of the fossilized skin of a 55 million-year-old leatherback turtle, an 86 million-year-old mosasaur and a 190 million year-old ichthyosaur. Microscopic analysis of the fossils showed oval bodies consistent with the look of melanosomes, and a technique called energy-dispersive X-ray microanalysis confirmed that they really were melanosomes rather than microbial contamination.