The oldest sample of mammalian hair ever found has been retrieved from a 100-million-year-old lump of amber. The scales on the hair – which provide its protective waterproof cover – are identical to those found on the hairs of mammals walking the Earth today.
This may mean that the structure of mammalian hair has remained unchanged for much of our evolution, says Romain Vullo at the University of Rennes I in France, who discovered the hair. "Perhaps mammalian hair does its job so well that it does not need to evolve."
Imprints of fur have been seen in two 160-million-year-old fossils in China, but this is the oldest example of actual hair, and therefore the first time researchers have been able to study the pattern of scales on their surface.
It turns out that the pattern is identical to that found on modern mammalian hair: rows of overlapping scales stacked on top of each other in an orderly fashion, with each row roughly 2 to 8 micrometres high.
This discovery is "wonderful progress", says Zhe-Xi Luo, Curator of Vertebrate Paleontology at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. "It shows the microstructure of hairs of mammals have always been the same."
Vullo discovered the amber-encased hair in the Font-de-Benon quarry in Charente-Maritime, south-western France. Around 100 million years ago, the site of what is now the quarry was a lush tropical forest.
Interpreting the ancient "crime scene" where the hair's owner died is fraught with difficulties.
First, how to identify the victim? The hair may have belonged to a small opossum-like animal. Four teeth discovered in the same quarry suggest a possible candidate: Arcantiodelphys marchandi, one of the oldest known marsupials.
What was the cause of death? The casing of the pupa of a carrion-eating blowfly discovered near the fur prompted George Poinar of the Department of Zoology at Oregon State University in Corvallis to speculate on how the creature met its end.
"A mammal that was running up and down a pine tree maybe got stuck in a pool of sap and perished," he says. "This was in the tropics, so the body decayed quickly, attracting carrion flies that laid their eggs in the carcass before the resin could solidify."
Alternatively, the hair may have been plucked off the creature as it brushed past some resin on a bough. "The puparium may be a red herring," says Poinar.
Journal reference: Naturwissenschaften, DOI 10.1007/s00114-010-0677-8
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