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 today (Jan. 8) in 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. (Sea Monster Album: See Images of Extinct Mosasaurs)
The study isn't the first to delve into the color of ancient creatures. Paleontologists have found that Microraptor, a small winged dinosaur from 130 million years ago, had black, crowlike feathers. The "dino-bird" Archaeopteryx had wing feathers with a black-and-white pattern, too, according to a 2012 study detailed in the journal Nature Communications. The color of ancient feathers is somewhat controversial, however, with some scientists suggesting the fossilization process might distort the pigment-containing organelles in the feathers.
But marine animal color was uncharted territory. 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. In fact, the black pigment eumelanin is extremely persistent in the environment, Lindgren said, so the presence of melanosomes may be the reason these skin halos survived.
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. Mosasaurs were reptilian, fishlike apex predators in the Cretaceous seas. Ichthyosaurs were also marine reptiles, but with their long snouts, they resembled modern dolphins.