Jurassic era squid ink composition still unchanged

Washington, May 22 (IANS) Two ink sacs from 160-million-year-old giant cephalopod fossils, discovered in 2010 in England, contain the pigment melanin, identical to the melanin found in the ink sac of a modern-day cuttlefish.

The finding, in an extremely rare case of being able to study organic material hundreds of millions of years old, suggests that the ink-screen escape mechanism of cephalopods - cuttlefish, squid and octopuses - has not evolved since the Jurassic period, and that melanin could be preserved intact in the fossils of a range of organisms.

"Though the other organic components of the cephalopod we studied are long gone, we've discovered through a variety of research methods that the melanin has remained in a condition that could be studied in exquisite detail," said study co-author John Simon, chemistry professor at the University of Virginia.

One of the ink sacs studied is the only intact ink sac ever discovered. Phillip Wilby of the British Geological Survey found it in Christian Malford, Wiltshire, England, west of london near Bristol, the journal Proceedings of the National Academy of Sciences reports.

He sent samples to Simon and Japanese chemist Shoskue Ito, both experts on melanin, who then engaged research colleagues in the US, the UK, Japan and India to investigate the samples using a combination of direct, high-resolution chemical techniques to determine whether or not the melanin had been preserved. It had, according to a Virginia statement.

The investigators then compared the chemical composition of the fossil melanin to the melanin in the ink of the modern cuttlefish, Sepia officinalis, common to the Mediterranean, North and Baltic seas. They found a match.

"It's close enough that I would argue that the pigmentation in this class of animals has not evolved in 160 million years," Simon said. "The whole machinery apparently has been locked in time and passed down through succeeding generations of cuttlefish. It's a very optimized system for this animal and has been optimized for a long time."

Generally animal tissue, made up mostly of protein, degrades quickly. Over the course of millions of years all that is likely to be found from an animal is skeletal remains or an impression of the shape of the animal in surrounding rock. But melanin is an exception. Though organic, it is highly resilient to degradation over the course of vast amounts of time.