The earliest traces of the color blue known to man may belong to an ancient extinct prehistoric bird. A team of scientists from the University of Sheffild has examined Eocoracias brachyptera and claims to have first identified color remains in fossils
The first traces of the blue color known to man they may belong to an ancient extinct prehistoric bird. A team of scientists from the University of Sheffild examined theEocoracias brachyptera and claims to have first identified the remnants of the color in fossils.
Blue is one of the hardest colors to find. Blue, green and iridescent feathers, like those of a hummingbird, are characterized by the so-called structural colors. Unlike normal colors, they do not derive from one pigment or more but arise from arrangement of molecular structures capable of reflecting light from different angles. In nature, the best known examples are peacock feathers or butterfly wings.
The merit of scientists was to find the first known evidence of this color in the animal kingdom. The lucky one was a bird that lived 48 million years ago. The shape and size of those small pigment-containing structures and the bird's family tree suggest that it had blue plumage.
The researchers examined 72 samples of modern bird feathers of different colors and 12 samples of organic material collected from the fossilized plumage of E. brachyptera. Next, they analyzed the shape and size of a type of cell structure called a pigment melanosoma found inside the pens, to "paint" a picture of these ancient animals.
What are melanosomes
The melanosomes involved in the production of different colors come in different shapes and sizes. The black, brown and gray colors are produced by pigments. Structural colors, whether iridescent or blue or green, are produced in two stages: the light is refracted by an air-filled layer of keratin within the feather, and an underlying layer of melanosomes absorbs the rest of the wavelengths. of the light. In the case of blue, this configuration includes a spongy, air-filled layer of keratin that covers a layer of black pigment-containing melanosomes.
"The upper layer is structured in such a way as to refract the light in blue wavelengths", explains Frane Babarović, an evolutionary biologist at the University of Sheffield, England. "The underlying melanosomes absorb the rest of the light."
Keratin is generally not well preserved in fossils, but melanosomes are, hence the choice of Babarović and colleagues to study the melanosome shapes of blue feathers. They confirmed that the melanosomes of modern blue-colored birds, such as those of E. brachyptera, were indeed unique in shape, were long (about 1.400 nanometers) and relatively wide (about 300 nanometers), larger than the melanosomes found in black feathers. .
But there is a zone of overlap: melanosomes for non-iridescent structural colors are similar in size and shape to those of gray pigments. The shape of the ancient bird's microstructure was similar to that of color-bound pigmented melanosomes Grey.
This could mean that blue and gray are evolutionarily linked. The overlap makes it difficult to know whether an ancient bird was just blue or, as is more common in modern birds, gray. But once blue evolved within a particular family group, the color continued to manifest itself in other family members.
Many of E. brachyptera's modern relatives, such as kingfishers and kookaburras, have blue feathers. A field so far little explored but which promises to be full of surprises and which will enrich our knowledge of the prehistoric palette of nature.
The study was published in the Journal of the Royal Society Interface.
READ also:
- Chick fossil discovered, sheds light on bird evolution
- Belone, the record-breaking bird hidden in amber for 100 million years
- Here's what the oldest color in the world is, according to scientists
Francesca Mancuso
Gallery
