Article: A highly pneumatic middle Cretaceous theropod from the British Lower Greensand

A series of axial elements from the Aptian Ferruginous Sands Formation of the Lower Greensand Group, discovered on the foreshore near Knock Cliff on the Isle of Wight, UK are (bar some isolated teeth and fragmentary postcranial material from the Cenomanian Cambridge Greensand) the youngest non‐avian theropod remains reported from the British Mesozoic. These specimens have the potential to shed light on a poorly known section of the European dinosaur record. Consistency in size, appearance and adhering matrix indicates that the vertebrae belong to the same individual. This was a mid‐sized tetanuran, the presence of several diagnostic characters indicating that it should be recognized as a new taxon, herein named Vectaerovenator inopinatus. The cervical and dorsal vertebrae are camerate and highly pneumatic. Tetanuran features include opisthocoelous cervicals and pneumatic foramina located within fossae; however, assigning this specimen to a specific clade is problematic. Within Tetanurae, Vectaerovenator possesses axial structures and homoplastic features seen in megalosauroids, carcharodontosaurians and certain coelurosaurs. Not only is Vectaerovenator one of the UK's youngest non‐bird dinosaurs, and one of few valid British Greensand taxa, it is also the first diagnosable theropod taxon to be named from Aptian deposits of Europe.

We thank Martin Munt and Alex Peaker (both Dinosaur Isle Museum, Sandown, Isle of Wight) for access to the material and for help and guidance regarding the geology of the Lower Greensand; Gary Blackwell (Dinosaur Isle Museum) for his excellent preparatory work on these delicate specimens; Martin Simpson for his help identifying the geological provenance of the material; Mark Chapman, Steve Vidovic (both University of Southampton) and Tom Smith (University of Bristol) for their advice with the phylogenetic analyses; and Dom Barker and Luis Coy (both University of Southampton) for their help with specimen photography. We would also like to thank Phillip Mannion and Sally Thomas, and reviewers Andrea Cau and Fernando Novas for their input and detailed insights during the review process that substantially improved the manuscript. The program TNT is made available thanks to the Willi Hennig Society. This study was supported by the Engineering and Physical Sciences Research Council (EPSRC), UK and the Institute for Life Sciences, University of Southampton, UK.