Building from the Inside Out – Fossils Reveal Hidden Secrets

By studying the remains of fossilized internal organs, Palaeontologists at University College Cork (UCC) have discovered a way to unlock more accurate information on the anatomy of ancient vertebrate animals. In this breakthrough study*, led by UCC’s Valentina Rossi and her supervisor Dr Maria McNamara in collaboration with an international team of chemists from the US and Japan, cutting-edge synchrotron techniques were used to analyse the chemistry of the fossil and modern melanosomes using X-rays, allowing them to peer inside the anatomy of fossils and uncover hidden features.

While previous studies have mainly been focused on the skin and feathers, the approach adopted by the UCC team was able to link the pigment is to visible colour. Unexpectedly, the new study also showed that melanin is abundant in internal organs of modern amphibians, reptiles, birds and mammals, and their fossil counterparts.

“This discovery is remarkable in that it opens up a new avenue for reconstructing the anatomy of ancient animals. In some of our fossils we can identify skin, lungs, the liver, the gut, the heart, and even connective tissue,” said senior author Dr Maria McNamara. “What’s more, this suggests that melanin had very ancient functions in regulating metal chemistry in the body going back tens, if not hundreds, of millions of years.”

The team made the initial discovery of internal melanosomes last year on fossil frogs. “After the pilot study, we had a hunch that these features would turn out to be more widespread across vertebrates. But we never guessed that the chemistry would be different in different organs,” Rossi said.

The advent of new synchrotron X-ray analysis techniques “allows us to harness the energy of really fast-moving electrons to detect minute quantities of different metals in the melanosomes.”

The fossils are so well-preserved that even the melanin molecule can be detected, the scientists added.

Published in Proceedings of the National Academy of Sciences of the United States of America