Flying squirrels are the only group of gliding mammals with a remarkable diversity and wide geographical range. However, their evolutionary story is not well known. Thus far, identification of extinct flying squirrels has been exclusively based on dental features, which, contrary to certain postcranial characters, are not unique to them. Therefore, fossils attributed to this clade may indeed belong to other squirrel groups. Here we report the oldest fossil skeleton of a flying squirrel (11.6 Ma) that displays the gliding-related diagnostic features shared by extant forms and allows for a recalibration of the divergence time between tree and flying squirrels. Our phylogenetic analyses combining morphological and molecular data generally support older dates than previous molecular estimates (~23 Ma), being congruent with the inclusion of some of the earliest fossils (~36 Ma) into this clade. They also show that flying squirrels experienced little morphological change for almost 12 million years.

Sebecosuchia was a group of highly specialized cursorial crocodyliforms that diversified during the Cretaceous and persist until the end of the Miocene. Their unique combination of cranial and post-cranial features indicates that they were active terrestrial predators that occupied the apex of the Late Cretaceous terrestrial ecosystems, even competing with theropod dinosaurs. Here, we report the discovery of the earliest sebecid worldwide, and the first from Eurasia, Ogresuchus furatus gen. et sp. nov., based on a semi-articulate specimen located in a titanosaurian sauropod nesting ground. The new taxon challenges current biogeographical models about the early dispersal and radiation of sebecid crocodylomorphs, and suggests an origin of the group much earlier than previously expected. Moreover, the new taxon suggests a potential convergent evolution between linages geographically isolated. Taphonomic evidences suggest that Ogresuchus died almost in the same place where fossilized, in a dinosaur nesting area. Biometric and morphologic observations lead to speculate that Ogresuchus could easily predate on sauropod hatchlings.

The neuroanatomy of hadrosaurid dinosaurs is well known from North America and Asia. In Europe only a few cranial remains have been recovered that include the braincase. Arenysaurus is the first European endocast for which the paleoneuroanatomy has been studied. The resulting data have enabled us to draw ontogenetic, phylogenetic and functional inferences. Arenysaurus preserves the endocast and the inner ear. This cranial material was CT scanned, and a 3D-model was generated. The endocast morphology supports a general pattern for hadrosaurids with some characters that distinguish it to a subfamily level, such as a brain cavity that is anteroposteriorly shorter or the angle of the major axis of the cerebral hemisphere to the horizontal in lambeosaurines. Both these characters are present in the endocast of Arenysaurus. Osteological features indicate an adult ontogenetic stage, while some paleoneuroanatomical features are indicative of a subadult ontogenetic stage. It is hypothesized that the presence of puzzling mixture of characters that suggest different ontogenetic stages for this specimen may reflect some degree of dwarfism in Arenysaurus. Regarding the inner ear, its structure shows differences from the ornithopod clade with respect to the height of the semicircular canals. These differences could lead to a decrease in the compensatory movements of eyes and head, with important implications for the paleobiology and behavior of hadrosaurid taxa such as Edmontosaurus, Parasaurolophus and Arenysaurus. The endocranial morphology of European hadrosaurids sheds new light on the evolution of this group and may reflect the conditions in the archipelago where these animals lived during the Late Cretaceous.

Titanosaur sauropods constituted one of the major dinosaur faunal components in Europe along the latest Cretaceous. Although they were abundant in the late Campanian -early Maastrichtian, titanosaurs apparently demised in terms of diversity and abundance in the late Maastrichtian Ibero-Armorican domain. Thus, any finding in this crucial period provides new clues to understand the biodiversity trend of the group prior to the K -Pg boundary. Here, we report the occurrence of a vertebral element attributed to a titanosaur in fluvial deposits dated as uppermost Maastrichtian (C29r chrone). The specimen corresponds to the right posterior part of a posterior cervical vertebra. CT-scan and histological analyses revealed high pneumatisation with laminar structures composed of compact bone, strongly remodelled with at least three generations of secondary osteons. These evidences suggest a relatively advanced age for the individual at death. Given that the partial vertebra was recovered from the uppermost portion of the late Maastrichtian, it might represent the youngest evidence for titanosaur sauropods in Europe discovered so far. Further, alongside to other remains (i.e. eggshells and footprints), the studied partial vertebra provides evidence for the persistence of this taxonomic group at the very end of the Cretaceous in southwestern Europe.