New sources of melanin pigment shake up ideas about fossil animals’ colour

A rethink of how scientists reconstruct the color of fossil birds, reptiles, and dinosaurs.

Melanosomes in extant frogs. a–v Histological sections stained with Fontana-Masson; melanosomes (and aggregates of melanosomes) appear black. Insets in f and v show isolated melanosomes. w–al Scanning electron micrographs. Scale bar in a, 20 µm, and same scale in a–v; scale bar in w, 2 µm, and same scale in w–al
Melanosomes in extant frogs. a–v Histological sections stained with Fontana-Masson; melanosomes (and aggregates of melanosomes) appear black. Insets in f and v show isolated melanosomes. w–al Scanning electron micrographs. Scale bar in a, 20 µm, and same scale in a–v; scale bar in w, 2 µm, and same scale in w–al

Numerous ongoing investigations of fossil color have expected that fossilized granules of melanin – melanosomes – originate from the skin. In any case, new confirmation demonstrates that different tissues–, for example, the liver, lungs, and spleen – can likewise contain melanosomes, recommending that fossil melanosomes may not give data on fossil color.

Scientists studied internal tissues in modern frogs with powerful microscopes and chemical techniques to show that internal melanosomes are highly abundant.

Dr. Maria McNamara, research led said, “This means that these internal melanosomes could make up the majority of the melanosomes preserved in some fossils.”

10 million-year-old frog from Libros, Spain, showing dark internal melanosomes in the chest cavity and legs. Museo Nacional de Ciencias Naturales, Madrid, Spain
10 million-year-old frog from Libros, Spain, showing dark internal melanosomes in the chest cavity and legs.
Museo Nacional de Ciencias Naturales, Madrid, Spain

The group additionally utilized rot tries and broke down fossils to demonstrate that the interior melanosomes can spill into other body parts amid the fossilization procedure – like snowflakes inside a snow globe.

Although, there is a way to tell the difference between melanosomes from internal organs and the skin.

Dr. McNamara added: “The size and shape of skin melanosomes are usually distinct from those in internal organs.”

“This will allow us to produce more accurate reconstructions of the original colors of ancient vertebrates.”

The study, published today in the journal Nature Communications, is led by UCC’s Dr. Maria McNamara in collaboration with her Ph.D. student Valentina Rossi, Dr. Paddy Orr from University College Dublin and an international team of paleontologists from the UK and Japan.

Collaborator Professor Mike Benton from the University of Bristol’s School of Earth Sciences added: “Understanding the origin of melanosomes is crucial in the new studies of color in dinosaurs and other extinct beasts.”