The reptile image worked on by the scientists.
Credit: University of Manchester
MANCHESTER: The organic compounds surviving in 50 million year old fossilised reptile skin have been revealed for the first time via an infra-red image produced by a team of palaeontologists and geochemists in the UK.
The brightly-coloured image shows the presence of amides – the organic compounds, or building blocks of life – in the ancient skin of an excellently preserved reptile found in the 50 million year-old rocks from the Green River Formation in Utah. The researchers are using technology to reveal and map the fossilised soft tissue.
“The ability to chemically analyse rare and precious fossils such as these without the need to remove material and destroy them is an important and long overdue addition to field of palaeontology,” said co-author Nick Edwards from the University of Manchester. “Hopefully this will provide future opportunities to unlock the information stored in other similarly preserved specimens.”
Trace metals protect the skin
These infra-red maps are backed up by the first ever element-specific maps of organic material in fossil skin generated using X-rays at the Stanford synchrotron in the U.S. by the researchers. The chemical details were clear enough that the scientists were able to propose how the high level of preservation occurred in the rocks.
When the original compounds in the skin begin to break down they can form chemical bonds with trace metals, and under ideal conditions these trace metals act like a ‘bridge’ to minerals in the sediments. This protects the skin material from being washed away or decomposing further.
The results of the study, published in Royal Society Proceedings B: Biology imply that trace metal inventories and patterns in ancient reptile skin, even after fossilisation, can indeed be compared to modern reptiles.
Uncovering the chemistry of ancient life
“The mapped distributions of organic compounds and trace metals in 50 million year old skin look so much like maps we’ve made of modern lizard skin as a check on our work, it is sometimes hard to tell which is the fossil and which is fresh,” said one of the researchers who led the team, Roy Wogelius from the University of Manchester.
“These new infra-red and X-ray methods reveal intricate chemical patterns that have been overlooked by traditional methods for decades.”
The new images are compelling, and represent the next step in the team’s research programme that aims to understand how such remarkable preservation occurs, and ultimately to discover the chemistry of ancient life.
How to map fossils safely
The infra-red light causes vibrations in the fossilised skin, and a map of where these vibrations occur can be obtained from a fossil by using a trick: a tiny crystal (like an old phonograph record stylus) which moves from point-to-point in a programmable grid across the surface.
At each point where the tiny crystal touches the fossil, an infra-red beam that shines through the crystal reflects off of the crystal base, but a small amount of the beam probes beyond the interface- and if organic compounds are present, they absorb portions of the beam and change the reflected signal.
This allows the team to non-destructively map large fossils which do not themselves transmit or reflect the beam – a revolutionary process for palaeontologists.
“The results of this study have wider implications, such as understanding what happens to buried wastes over long periods of time. The fossil record provides us with a long-running experiment, from which we can learn in order to help resolve current problems.” said Phil Manning from the University of Manchester, who also led the research.
With the University of Manchester
