Fossilized Skin Pigments Reveal Colors Of Ancient Sea Monsters

January 9, 2014
Image Caption: Preserved pigment in fossilized skin from a leatherback turtle, a mosasaur and an ichthyosaur suggests that these animals were, at least partially, dark-colored in life -- an example of convergent evolution. Note that the leatherback turtle and mosasaur have a dark back and light belly (a color scheme also known as countershading), whereas the ichthyosaur, similar to the modern deep-diving sperm whale, is uniformly dark-colored. Credit: Illustration by Stefan Sølberg

redOrbit Staff & Wire Reports – Your Universe Online

Newly discovered fossilized skin pigments from a trio of multi-million-year-old marine reptiles reveal that these real-life sea monsters were at least partially dark colored when they were alive, according to research appearing in the latest edition of the journal Nature.

The fact that creatures such as mosasaurs and ichthyosaurs were dark-colored is likely to have contributed to more efficient thermoregulation, while also serving as camouflage and protecting the reptiles from harmful UV radiation, Lund University geologist Johan Lindgren and an international team of colleagues explained in the report.

Previously, experts could only guess what color these massive marine creatures were. Now, however, pigment preserved in the fossilized skin of a 55 million-year-old leatherback turtle, an 85 million-year-old mosasaur and a 196 million-year-old ichthyosaur has, for the first time, revealed the color scheme of an extinct marine animal.

“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 Lindgren. “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.”

In addition to dark skin patches containing “masses of micrometer-sized, oblate bodies,” the fossils at the heart of the study were also composed of skeletal remains, the researchers said. The microbodies had previously been identified as fossilized bacteria that caused the reptile carcasses to decompose and degrade.

However, analysis of the soft tissue’s chemical content at the at SP Technical Research Institute of Sweden and Lund University’s MAX IV Laboratory revealed that they are actually remnants of the creature’s own colors, and that the microbodies are actually pigment-containing cellular organelles known as fossilized melanosomes.

“Our results really are amazing,” study co-author Per Uvdal of the MAX IV Laboratory said. “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 finally use sophisticated molecular and imaging techniques to learn what these animals looked like and how they lived.”

Lindgren noted that the fossilized leatherback turtle had a similar color scheme to the modern-day Dermochelys, which possesses an almost entirely black back which allows them to heat up more quickly and reach higher body temperatures. He believes that the darkly-colored skin held the same properties for mosasaurs and ichthyosaurs, which would have welcomed the ability to warm-up quickly in between dives.

“If their interpretations are correct, then at least some ichthyosaurs were uniformly dark-colored in life, unlike most living marine animals,” the university explained. “However, the modern deep-diving sperm whale has a similar color scheme, perhaps as camouflage in a world without light, or as UV protection, given that these animals spend extended periods of time at or near the sea surface in between dives.”

Source: redOrbit Staff & Wire Reports - Your Universe Online

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