An international team of scientists from the Universities of Bonn (Germany), Rennes (France) and Chicago (USA) led by the Autonomous University of Madrid (Spain) has discovered the evolutionary roots of mammalian hair thanks to the analysis of the fossil remains of a small mammal that lived in the Las Hoyas site in Cuenca (Spain) 125 million years ago and that lived with dinosaurs.
The remains of this mammal belong to a new species called Spinolestes xenarthrosus , within a primitive group of extinct mammals, the triconodonts. The Spinolestes had a size similar to a possum, weighed about 50-70 grams , had a lush mane of long hair and a back covered with thorns as if it were a hedgehog. It fed on insects and larvae and lived in a similar way to today’s armored shrews.
It is the only mammal discovered so far in this rich Lower Cretaceous site (which was one of the first tropical wetlands on the planet) and thanks to the excellent preservation conditions of the fossil, scientists have been able to identify the evolutionary origins of hair in the mammals.
“It is the first fossil species that unequivocally reveals the microscopic structure of the hair that covers the skin of modern mammals. The finding shows that, contrary to what was believed, the evolution of hair, along with other structures of the skin, did not occur gradually, but took place simultaneously at the origin of the lineage “, explains Angela D. Buscalioni, leader of the study .
The study, which shows how these results have been obtained thanks to scanning electron microscopy techniques , computed tomography and X-ray energy dispersive mineral composition analysis, has been published in the journal Nature .
