Genus: Calvarius PRIETO-MARQUES & SELLES, 2023
Etymology:In reference to a nearby hill known as Serrat del Calvari. It is also a derivation of the Catalan 'calvari' ('suffering'), alluding to the chronostratigraphic proximity of MCD-8734 to the K-Pg extinction event.

Species: rapidus PRIETO-MARQUES & SELLES, 2023
Etymology: The species name means 'quic' or 'fast' in Latin, referring to the likely curosorial adaptations of this animal.

Holotype: MCD-8734

Locality: Masia de Ramon site, located 2.6 km south of Figuerola d'Orcau, a small village near the municipality of Isona i Conca Della, Pallars Jussa County, lleida Province, North-Western Catalonia.

Horizon: Uppar part o f the Talarn Formation, Tremp Group.

Biostratigraphy:

Age: Latest Maastrichtian Stage, Latest Senonian Subepoch, Latest Gulf Epoch, Latest Late Cretaceous.

Material: A left metatarsal IV.

A) Dorsal; B) Laterial; C) Plantar and D) Medial views (after Prieto-Marquez & Selles, 2023).