Late Cretaceous European theropod palaeobiodiversity, palaeobiogeography and the intra-Maastrichtian faunal turnover: new contributions from the Iberian fossil site of Laño

A total of 227 theropod teeth have so far been recovered from the late Campanian Laño site (northern Iberian Peninsula). The teeth were studied for their qualitative and quantitative features. From the theropod sample found at Laño, seven morphotypes attributed to five taxa are identified: a medium to large abelisaurid (Arcovenator sp.) and four small coelurosaurians (Dromaeosauridae indet., Paraves indet., cf. Paronychodon sp. and cf. Richardoestesia sp.). Together with the ground bird Gargantuavis and a possible ornithomimosaur, the theropod fauna of Laño might be composed of two medium- to large-sized non-avian theropods, four small-bodied non-avian theropods and a large terrestrial bird. This makes the Laño site the richest and most diverse latest Cretaceous theropod site of Europe. Furthermore, the Laño site and the Late Cretaceous localities of Europe that have yielded theropod remains suggest that the medium- to large-sized theropods were abelisaurids or indeterminate theropods. The small theropods are more abundant, diverse and represented by different dromaeosaurids, Paronychodon, Richardoestesia, or related forms, troodontids and, probably, by other paravians. Among birds, enantiornithines, gargantuaviids and ornithurines are also common in the European Late Cretaceous sites. The theropod assemblage of Laño, together with the taxa of other Late Cretaceous sites, supports the idea that several theropod dispersal events took place during the Cretaceous. This resulted in a mixture of European endemic, Asiamerican and Gondwanan forms. This study also supports the hypothesis that the intra-Maastrichtian faunal turnover that occurred in the Ibero-Armorican landmass seems to have had no effect on theropods.

Methods
The dataset of the theropod teeth measurements was built by measuring the teeth recovered from the Laño site (northern Iberia) and by collecting data from other already published datasets cited on the documents.

For the documents that gather the theropod record of Europe during the Turonian-Maastrichtian, the data was collected from former published articles as well as this work. Furthermore, in some cases, this record has been reassigned to other taxa in this work.