New research published in the journal Scientific Reports reveals that a team of researchers has for the first time discovered direct chemical evidence that the fossilized remains of one type of bird-like dinosaurs retain melanosomes and the pigments which they produced.
The discovery was made by an international team of researchers, including Brown University graduate student Ryan Carney, and reinforces the belief that scientists are able to determine the coloration of creatures that have long since died off, the study authors said in a statement.
Carney and his colleagues were studying fossilized feathers from Anchiornis huxleyi, a bird-like dinosaur which died about 150 million years ago in China. They correlated the unique chemical signature of animal pigments with physical evidence of melanosome organelles in the creature’s remains, ending a longstanding debate by proving that they are indeed preserved in fossils.
“Our study provides three new pieces of evidence to demonstrate that these fossil microbodies in question are melanosomes and not microbes,” Carney told redOrbit via email. “1) Molecular evidence of melanin associated with these microbodies in dinosaur feathers. 2) Furthermore, this molecular signature, or ‘fingerprint’, is that of animal melanin, not microbial melanin, which is important because a few types of microbes actually do produce melanin. 3) We found no evidence of any microbial molecules.”
“Ultimately, this chemical evidence of animal-specific melanin in fossil feathers is the final nail in the coffin that shows that these microbodies are indeed melanosomes and not microbes – not just because the evidence is conclusive, but also because it is exhaustive,” he added. “Objectively, there are no more remaining arguments against the melanosome hypothesis that have been put forth in the scientific literature. Additionally, no positive evidence has been put forth in favor of the microbe hypothesis.”
Findings made possible due to high-tech research tools
The findings also have important implications for past and future research on fossil color, the study authors explained. Carney said that it supports previous studies of fossil melanosomes and paleo-color, while also demonstrating that paleontologists will be able to continue reconstructing the coloration of ancient creatures in the future.
The research team was led by Johan Lindgren of Lund University in Sweden, and used electron microscopes to detect what appeared to be rod-like melanosome structures and imprints inside of the barbules of feathers all over the body a Anchiornis huxleyi speciment. They also conducted a pair of chemical analyses to see if they could detect animal eumelanin pigment.
Using both time-of-flight secondary ion mass spectrometry and infrared reflectance spectroscopy they attempted to detect the molecular signature of melanin in the samples, then compared those observations with the modern-day animal eumelanin. Except for traces of sulfur in the fossil, the two melanins were virtually identical, Carney said. They also compared these spectral signals to melanins produced by various microbes to verify that they were from animal sources.
“This work, as well as my research on the evolution of flight, are all made possible thanks to relatively recent advances in technology, from molecular probing to x-ray imaging and computer animation,” Carney told redOrbit. “Basically, it is an amazing time to be a paleontologist!”
Feature Image: Anchiornis huxleyi specimen. (Credit: Thierry Hubin/RBINS)