The "A." sp. was discovered in 2007. It was found in the course of the construction of a high-speed rail track connecting Madrid with Valencia, in a fossil site that many animals were found in, in the Villalba de la Sierra Formation. The site was at a locality named “Lo Hueco,” near the village of Fuentes, Castile-La Mancha, Spain. Over the course of several months, a large-scale emergency excavation by over 60 paleontologists and 100 manual workers allowed thousands of specimens of plants, invertebrates, and vertebrates of late Campanian-early Maastrichtian age to be saved, including "A." sp.