Nav: Home

A fossilized snake shows its true colors

March 31, 2016

Ten million years ago, a green and black snake lay coiled in the Spanish undergrowth. Once, paleontologists would have been limited to the knowledge they could glean from its colorless fossil remains, but now they know what the snake looked like and can guess how it acted. Researchers reporting on March 31 in Current Biology have discovered that some fossils can retain evidence of skin color from multiple pigments and structural colors, aiding research into the evolution and function of color.

So far, scientists filling the ancient-Earth coloring book with pigment have been limited to browns, blacks, and muddy reds when melanin lasts as organic material. No other pigments have been shown to survive fossilization. But this snake's skin was fossilized in calcium phosphate, a mineral that preserves details on a subcellular level.

The fossilized snakeskin maintained the unique shapes of different types of pigment cells, which would have created yellows, greens, blacks, browns, and iridescence while the animal was alive. The pigments themselves are now decayed, but with the cell shapes--specific to each kind of pigment--mineralized, there's enough information to reconstruct their colors.

"When you get fossil tissues preserved with this kind of detail, you're just gobsmacked when you're looking at it under the microscope," says first author Maria McNamara, a paleobiologist at University College Cork. "I was astounded. You almost can't believe what you're seeing."

McNamara first came across the fossilized snake while conducting her PhD research on fossils from the Libros site in Spain, but she only recently analyzed the specimen. Her team discovered the mineralized skin cells when viewing the fossil under a high-powered scanning electron microscope and then matched the shapes up with pigment cells in modern snakes to determine what colors they might have produced.

"For the first time, we're seeing that mineralized tissues can preserve evidence of color," says McNamara. The researchers determined that the fossilized snakeskin had three types of pigment cells in various combinations: melanophores, which contain the pigment melanin; xanthophores, which contain carotenoid and pterin pigments; and iridophores, which create iridescence. All told, the snake was a mottled green and black, with a pale underside--colors that likely aided in daytime camouflage.

"Up until this discovery, the only prospect for skin color being preserved in fossils was organic remains related to melanin," says McNamara. "But now that we know color can be preserved even for tissues that are mineralized, it's very exciting."

Calcium phosphate mainly shows up in fossil bones and shells, but records do exist of so-called phosphatized skin. This discovery opens the door for re-analysis of these fossils, occurring across a wide range of creatures and locations, for evidence of color preservation. And knowing the color of an animal can also clue researchers in to some aspects of its behavior and evolution.

"It'll mean re-evaluating a lot of specimens that might have been overlooked," says McNamara.
-end-
Funding was provided by an Enterprise Ireland Basic Research Grant, an IRCSET-Marie Curie International Mobility Fellowship, and a Marie Curie Career Integration Grant.

Current Biology, McNamara et al.: "Reconstructing carotenoid-based and structural coloration in fossil skin" http://dx.doi.org/10.1016/j.cub.2016.02.038

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Learn more at http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.

Cell Press

Related Evolution Articles:

Prebiotic evolution: Hairpins help each other out
The evolution of cells and organisms is thought to have been preceded by a phase in which informational molecules like DNA could be replicated selectively.
How to be a winner in the game of evolution
A new study by University of Arizona biologists helps explain why different groups of animals differ dramatically in their number of species, and how this is related to differences in their body forms and ways of life.
The galloping evolution in seahorses
A genome project, comprising six evolutionary biologists from Professor Axel Meyer's research team from Konstanz and researchers from China and Singapore, sequenced and analyzed the genome of the tiger tail seahorse.
Fast evolution affects everyone, everywhere
Rapid evolution of other species happens all around us all the time -- and many of the most extreme examples are associated with human influences.
Landscape evolution and hazards
Landscapes are formed by a combination of uplift and erosion.
New insight into enzyme evolution
How enzymes -- the biological proteins that act as catalysts and help complex reactions occur -- are 'tuned' to work at a particular temperature is described in new research from groups in New Zealand and the UK, including the University of Bristol.
The evolution of Dark-fly
On Nov. 11, 1954, Syuiti Mori turned out the lights on a small group of fruit flies.
A look into the evolution of the eye
A team of researchers, among them a zoologist from the University of Cologne, has succeeded in reconstructing a 160 million year old compound eye of a fossil crustacean found in southeastern France visible.
Is evolution more intelligent than we thought?
Evolution may be more intelligent than we thought, according to a University of Southampton professor.
The evolution of antievolution policies
Organized opposition to the teaching of evolution in public schoolsin the United States began in the 1920s, leading to the famous Scopes Monkey trial.

Related Evolution Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".