Fossil Pigment Remains Reveal True Colors of Ancient Sea Monsters

During the age of the dinosaurs, giant reptiles ruled the ocean. These "sea monsters" included the mosasaurs and ichthyosaurs, marine animals that looked a bit like the dolphins, sharks and turtles of today. Until now, though, exactly what colors these animals might have been has been a mystery. But scientists have recently uncovered soft tissue remains, revealing exactly what these species might have looked like.

"This is fantastic! When I started studying at Lund University in 1993, the film Jurassic Park had just been released, and that was one of the main reasons why I got interested in biology and palaeontology," said Johan Lindgren, one of the researchers, in a news release. "Then, 20 years ago, it was unthinkable that we would ever find biological remains from animals that have been extinct for many millions of years, but now we are there and I am proud to be a part of it."

The soft tissue remains were taken from a 55 million-year-old leatherback turtle, an 85 million-year-old mosasaur and a 196-190 million-year-old ichthyosaur. The remains themselves were composed of skeletal remains in addition to dark skin patches containing masses of micrometer-sized, oblate bodies. These microbodies were previously interpreted to be the fossilized remains of bacteria that once contributed to the decomposition and degradation of the carcasses. Yet by studying the chemical content of the soft tissues, the scientists showed that they were the remnants of the animals' colors.

"Our results really are amazing," said Per Uvdal, one of the researchers, in a news release. "The pigment melanin is almost unbelievably stable. Our discovery enables us to make a journey through time and to revisit these ancient reptiles using their own biomolecules. Now we can use sophisticated molecular and imaging techniques to learn what these animals looked like and how they lived."

So what did they look like? The animals were all dark colored, which likely helped with thermoregulation and provided means for camouflage and protection against UV radiation. This is partly unsurprising; the living leatherback sea turtles of today also have an almost entirely black back, which allows them to cope with environments that range from tropical to cold.

The findings reveal a bit more about these ancient creatures. More specifically, they show how these now-extinct creatures once looked. In the future, it may be possible to analyze other animals and learn what they might have looked like, as well.

The findings are published in the journal Nature.