Fylax thyrakolasus Prieto-Márquez & Carrera Farias, 2021 (new genus and species)
(Type jaw of Fylax thyrakolasus with a close-up of its teeth in the upper right, from Prieto-Márquez and Carrera Farias, 2021)
Meaning of name: Fylax thyrakolasus = keeper of the gates of hell [referring to the fact that it lived near the end-Cretaceous mass extinction]
Age: Late Cretaceous (Maastrichtian), very close to the Cretaceous–Paleogene boundary
Where found: Figuerola Formation, Catalonia, Spain
How much is known: The left half of a partial lower jaw.
Notes: Fylax was a hadrosauroid, closely related to but not a member of the "core group” of duck-billed dinosaurs (hadrosaurids). It is the youngest known non-hadrosaurid hadrosauroid. The coronoid process on its jaw (which would have been an attachment point for some of the main jaw-closing muscles) was unusually wide. Another notable feature of Fylax was that the chewing surface formed by its teeth was steeply angled, suggesting that it chewed its food primarily using a slicing motion.
Reference: Prieto-Márquez, A. and M.Á. Carrera Farias. 2021. A new late-surviving early diverging Ibero-Armorican duck-billed dinosaur and the role of the Late Cretaceous European Archipelago in hadrosauroid biogeography. Acta Palaeontologica Polonica advance online publication. doi: 10.4202/app.00821.2020
