The remains, dinosaur feathers and mammalian hairs, belong to the Lower Cretaceous, between 105 and 110 million years old, whose description and analysis have been published in the journal Scientific Reports.
The research team, made up of Sergio Álvarez Parra, Xavier Delclòs (both from the University of Barcelona), Mónica M. Solórzano Kraemer (Senckenberg Museum of Natural History in Frankfurt am Main), Luis Alcalá (Fundación Conjunto Paleontológico de Teruel-Dinópolis) and Enrique Peñalver (Geological and Mining Institute of Spain) has unraveled the origin of the two pieces found in the resin produced in an aerial environment in that period of time.
The pieces were located in two different locations: one was found years ago in the San Just amber deposit, in the municipality of Utrillas (dinosaur feathers), and the other in Ariño, in the excavation during the summer of 2019 in order to extract amber in the Santa María mine. What they did not expect was to find vertebrate remains embedded in the amber. It is precisely this last piece that corresponds to the discovery of the oldest mammal hair in amber in the world.
Ariño amber has three mammalian hairs with their characteristic pattern of microscopic scales, exceptionally well preserved thanks to amber. The parallel arrangement of the three hairs and their similar proportions allow researchers to identify it as a small tuft of a mammal.